Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * tuplesort.c
4 : : * Generalized tuple sorting routines.
5 : : *
6 : : * This module provides a generalized facility for tuple sorting, which can be
7 : : * applied to different kinds of sortable objects. Implementation of
8 : : * the particular sorting variants is given in tuplesortvariants.c.
9 : : * This module works efficiently for both small and large amounts
10 : : * of data. Small amounts are sorted in-memory using qsort(). Large
11 : : * amounts are sorted using temporary files and a standard external sort
12 : : * algorithm.
13 : : *
14 : : * See Knuth, volume 3, for more than you want to know about external
15 : : * sorting algorithms. The algorithm we use is a balanced k-way merge.
16 : : * Before PostgreSQL 15, we used the polyphase merge algorithm (Knuth's
17 : : * Algorithm 5.4.2D), but with modern hardware, a straightforward balanced
18 : : * merge is better. Knuth is assuming that tape drives are expensive
19 : : * beasts, and in particular that there will always be many more runs than
20 : : * tape drives. The polyphase merge algorithm was good at keeping all the
21 : : * tape drives busy, but in our implementation a "tape drive" doesn't cost
22 : : * much more than a few Kb of memory buffers, so we can afford to have
23 : : * lots of them. In particular, if we can have as many tape drives as
24 : : * sorted runs, we can eliminate any repeated I/O at all.
25 : : *
26 : : * Historically, we divided the input into sorted runs using replacement
27 : : * selection, in the form of a priority tree implemented as a heap
28 : : * (essentially Knuth's Algorithm 5.2.3H), but now we always use quicksort
29 : : * for run generation.
30 : : *
31 : : * The approximate amount of memory allowed for any one sort operation
32 : : * is specified in kilobytes by the caller (most pass work_mem). Initially,
33 : : * we absorb tuples and simply store them in an unsorted array as long as
34 : : * we haven't exceeded workMem. If we reach the end of the input without
35 : : * exceeding workMem, we sort the array using qsort() and subsequently return
36 : : * tuples just by scanning the tuple array sequentially. If we do exceed
37 : : * workMem, we begin to emit tuples into sorted runs in temporary tapes.
38 : : * When tuples are dumped in batch after quicksorting, we begin a new run
39 : : * with a new output tape. If we reach the max number of tapes, we write
40 : : * subsequent runs on the existing tapes in a round-robin fashion. We will
41 : : * need multiple merge passes to finish the merge in that case. After the
42 : : * end of the input is reached, we dump out remaining tuples in memory into
43 : : * a final run, then merge the runs.
44 : : *
45 : : * When merging runs, we use a heap containing just the frontmost tuple from
46 : : * each source run; we repeatedly output the smallest tuple and replace it
47 : : * with the next tuple from its source tape (if any). When the heap empties,
48 : : * the merge is complete. The basic merge algorithm thus needs very little
49 : : * memory --- only M tuples for an M-way merge, and M is constrained to a
50 : : * small number. However, we can still make good use of our full workMem
51 : : * allocation by pre-reading additional blocks from each source tape. Without
52 : : * prereading, our access pattern to the temporary file would be very erratic;
53 : : * on average we'd read one block from each of M source tapes during the same
54 : : * time that we're writing M blocks to the output tape, so there is no
55 : : * sequentiality of access at all, defeating the read-ahead methods used by
56 : : * most Unix kernels. Worse, the output tape gets written into a very random
57 : : * sequence of blocks of the temp file, ensuring that things will be even
58 : : * worse when it comes time to read that tape. A straightforward merge pass
59 : : * thus ends up doing a lot of waiting for disk seeks. We can improve matters
60 : : * by prereading from each source tape sequentially, loading about workMem/M
61 : : * bytes from each tape in turn, and making the sequential blocks immediately
62 : : * available for reuse. This approach helps to localize both read and write
63 : : * accesses. The pre-reading is handled by logtape.c, we just tell it how
64 : : * much memory to use for the buffers.
65 : : *
66 : : * In the current code we determine the number of input tapes M on the basis
67 : : * of workMem: we want workMem/M to be large enough that we read a fair
68 : : * amount of data each time we read from a tape, so as to maintain the
69 : : * locality of access described above. Nonetheless, with large workMem we
70 : : * can have many tapes. The logical "tapes" are implemented by logtape.c,
71 : : * which avoids space wastage by recycling disk space as soon as each block
72 : : * is read from its "tape".
73 : : *
74 : : * When the caller requests random access to the sort result, we form
75 : : * the final sorted run on a logical tape which is then "frozen", so
76 : : * that we can access it randomly. When the caller does not need random
77 : : * access, we return from tuplesort_performsort() as soon as we are down
78 : : * to one run per logical tape. The final merge is then performed
79 : : * on-the-fly as the caller repeatedly calls tuplesort_getXXX; this
80 : : * saves one cycle of writing all the data out to disk and reading it in.
81 : : *
82 : : * This module supports parallel sorting. Parallel sorts involve coordination
83 : : * among one or more worker processes, and a leader process, each with its own
84 : : * tuplesort state. The leader process (or, more accurately, the
85 : : * Tuplesortstate associated with a leader process) creates a full tapeset
86 : : * consisting of worker tapes with one run to merge; a run for every
87 : : * worker process. This is then merged. Worker processes are guaranteed to
88 : : * produce exactly one output run from their partial input.
89 : : *
90 : : *
91 : : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
92 : : * Portions Copyright (c) 1994, Regents of the University of California
93 : : *
94 : : * IDENTIFICATION
95 : : * src/backend/utils/sort/tuplesort.c
96 : : *
97 : : *-------------------------------------------------------------------------
98 : : */
99 : :
100 : : #include "postgres.h"
101 : :
102 : : #include <limits.h>
103 : :
104 : : #include "commands/tablespace.h"
105 : : #include "miscadmin.h"
106 : : #include "pg_trace.h"
107 : : #include "storage/shmem.h"
108 : : #include "utils/guc.h"
109 : : #include "utils/memutils.h"
110 : : #include "utils/pg_rusage.h"
111 : : #include "utils/tuplesort.h"
112 : :
113 : : /*
114 : : * Initial size of memtuples array. We're trying to select this size so that
115 : : * array doesn't exceed ALLOCSET_SEPARATE_THRESHOLD and so that the overhead of
116 : : * allocation might possibly be lowered. However, we don't consider array sizes
117 : : * less than 1024.
118 : : *
119 : : */
120 : : #define INITIAL_MEMTUPSIZE Max(1024, \
121 : : ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1)
122 : :
123 : : /* GUC variables */
124 : : bool trace_sort = false;
125 : :
126 : : #ifdef DEBUG_BOUNDED_SORT
127 : : bool optimize_bounded_sort = true;
128 : : #endif
129 : :
130 : :
131 : : /*
132 : : * During merge, we use a pre-allocated set of fixed-size slots to hold
133 : : * tuples. To avoid palloc/pfree overhead.
134 : : *
135 : : * Merge doesn't require a lot of memory, so we can afford to waste some,
136 : : * by using gratuitously-sized slots. If a tuple is larger than 1 kB, the
137 : : * palloc() overhead is not significant anymore.
138 : : *
139 : : * 'nextfree' is valid when this chunk is in the free list. When in use, the
140 : : * slot holds a tuple.
141 : : */
142 : : #define SLAB_SLOT_SIZE 1024
143 : :
144 : : typedef union SlabSlot
145 : : {
146 : : union SlabSlot *nextfree;
147 : : char buffer[SLAB_SLOT_SIZE];
148 : : } SlabSlot;
149 : :
150 : : /*
151 : : * Possible states of a Tuplesort object. These denote the states that
152 : : * persist between calls of Tuplesort routines.
153 : : */
154 : : typedef enum
155 : : {
156 : : TSS_INITIAL, /* Loading tuples; still within memory limit */
157 : : TSS_BOUNDED, /* Loading tuples into bounded-size heap */
158 : : TSS_BUILDRUNS, /* Loading tuples; writing to tape */
159 : : TSS_SORTEDINMEM, /* Sort completed entirely in memory */
160 : : TSS_SORTEDONTAPE, /* Sort completed, final run is on tape */
161 : : TSS_FINALMERGE, /* Performing final merge on-the-fly */
162 : : } TupSortStatus;
163 : :
164 : : /*
165 : : * Parameters for calculation of number of tapes to use --- see inittapes()
166 : : * and tuplesort_merge_order().
167 : : *
168 : : * In this calculation we assume that each tape will cost us about 1 blocks
169 : : * worth of buffer space. This ignores the overhead of all the other data
170 : : * structures needed for each tape, but it's probably close enough.
171 : : *
172 : : * MERGE_BUFFER_SIZE is how much buffer space we'd like to allocate for each
173 : : * input tape, for pre-reading (see discussion at top of file). This is *in
174 : : * addition to* the 1 block already included in TAPE_BUFFER_OVERHEAD.
175 : : */
176 : : #define MINORDER 6 /* minimum merge order */
177 : : #define MAXORDER 500 /* maximum merge order */
178 : : #define TAPE_BUFFER_OVERHEAD BLCKSZ
179 : : #define MERGE_BUFFER_SIZE (BLCKSZ * 32)
180 : :
181 : :
182 : : /*
183 : : * Private state of a Tuplesort operation.
184 : : */
185 : : struct Tuplesortstate
186 : : {
187 : : TuplesortPublic base;
188 : : TupSortStatus status; /* enumerated value as shown above */
189 : : bool bounded; /* did caller specify a maximum number of
190 : : * tuples to return? */
191 : : bool boundUsed; /* true if we made use of a bounded heap */
192 : : int bound; /* if bounded, the maximum number of tuples */
193 : : int64 tupleMem; /* memory consumed by individual tuples.
194 : : * storing this separately from what we track
195 : : * in availMem allows us to subtract the
196 : : * memory consumed by all tuples when dumping
197 : : * tuples to tape */
198 : : int64 availMem; /* remaining memory available, in bytes */
199 : : int64 allowedMem; /* total memory allowed, in bytes */
200 : : int maxTapes; /* max number of input tapes to merge in each
201 : : * pass */
202 : : int64 maxSpace; /* maximum amount of space occupied among sort
203 : : * of groups, either in-memory or on-disk */
204 : : bool isMaxSpaceDisk; /* true when maxSpace is value for on-disk
205 : : * space, false when its value for in-memory
206 : : * space */
207 : : TupSortStatus maxSpaceStatus; /* sort status when maxSpace was reached */
208 : : LogicalTapeSet *tapeset; /* logtape.c object for tapes in a temp file */
209 : :
210 : : /*
211 : : * This array holds the tuples now in sort memory. If we are in state
212 : : * INITIAL, the tuples are in no particular order; if we are in state
213 : : * SORTEDINMEM, the tuples are in final sorted order; in states BUILDRUNS
214 : : * and FINALMERGE, the tuples are organized in "heap" order per Algorithm
215 : : * H. In state SORTEDONTAPE, the array is not used.
216 : : */
217 : : SortTuple *memtuples; /* array of SortTuple structs */
218 : : int memtupcount; /* number of tuples currently present */
219 : : int memtupsize; /* allocated length of memtuples array */
220 : : bool growmemtuples; /* memtuples' growth still underway? */
221 : :
222 : : /*
223 : : * Memory for tuples is sometimes allocated using a simple slab allocator,
224 : : * rather than with palloc(). Currently, we switch to slab allocation
225 : : * when we start merging. Merging only needs to keep a small, fixed
226 : : * number of tuples in memory at any time, so we can avoid the
227 : : * palloc/pfree overhead by recycling a fixed number of fixed-size slots
228 : : * to hold the tuples.
229 : : *
230 : : * For the slab, we use one large allocation, divided into SLAB_SLOT_SIZE
231 : : * slots. The allocation is sized to have one slot per tape, plus one
232 : : * additional slot. We need that many slots to hold all the tuples kept
233 : : * in the heap during merge, plus the one we have last returned from the
234 : : * sort, with tuplesort_gettuple.
235 : : *
236 : : * Initially, all the slots are kept in a linked list of free slots. When
237 : : * a tuple is read from a tape, it is put to the next available slot, if
238 : : * it fits. If the tuple is larger than SLAB_SLOT_SIZE, it is palloc'd
239 : : * instead.
240 : : *
241 : : * When we're done processing a tuple, we return the slot back to the free
242 : : * list, or pfree() if it was palloc'd. We know that a tuple was
243 : : * allocated from the slab, if its pointer value is between
244 : : * slabMemoryBegin and -End.
245 : : *
246 : : * When the slab allocator is used, the USEMEM/LACKMEM mechanism of
247 : : * tracking memory usage is not used.
248 : : */
249 : : bool slabAllocatorUsed;
250 : :
251 : : char *slabMemoryBegin; /* beginning of slab memory arena */
252 : : char *slabMemoryEnd; /* end of slab memory arena */
253 : : SlabSlot *slabFreeHead; /* head of free list */
254 : :
255 : : /* Memory used for input and output tape buffers. */
256 : : size_t tape_buffer_mem;
257 : :
258 : : /*
259 : : * When we return a tuple to the caller in tuplesort_gettuple_XXX, that
260 : : * came from a tape (that is, in TSS_SORTEDONTAPE or TSS_FINALMERGE
261 : : * modes), we remember the tuple in 'lastReturnedTuple', so that we can
262 : : * recycle the memory on next gettuple call.
263 : : */
264 : : void *lastReturnedTuple;
265 : :
266 : : /*
267 : : * While building initial runs, this is the current output run number.
268 : : * Afterwards, it is the number of initial runs we made.
269 : : */
270 : : int currentRun;
271 : :
272 : : /*
273 : : * Logical tapes, for merging.
274 : : *
275 : : * The initial runs are written in the output tapes. In each merge pass,
276 : : * the output tapes of the previous pass become the input tapes, and new
277 : : * output tapes are created as needed. When nInputTapes equals
278 : : * nInputRuns, there is only one merge pass left.
279 : : */
280 : : LogicalTape **inputTapes;
281 : : int nInputTapes;
282 : : int nInputRuns;
283 : :
284 : : LogicalTape **outputTapes;
285 : : int nOutputTapes;
286 : : int nOutputRuns;
287 : :
288 : : LogicalTape *destTape; /* current output tape */
289 : :
290 : : /*
291 : : * These variables are used after completion of sorting to keep track of
292 : : * the next tuple to return. (In the tape case, the tape's current read
293 : : * position is also critical state.)
294 : : */
295 : : LogicalTape *result_tape; /* actual tape of finished output */
296 : : int current; /* array index (only used if SORTEDINMEM) */
297 : : bool eof_reached; /* reached EOF (needed for cursors) */
298 : :
299 : : /* markpos_xxx holds marked position for mark and restore */
300 : : int64 markpos_block; /* tape block# (only used if SORTEDONTAPE) */
301 : : int markpos_offset; /* saved "current", or offset in tape block */
302 : : bool markpos_eof; /* saved "eof_reached" */
303 : :
304 : : /*
305 : : * These variables are used during parallel sorting.
306 : : *
307 : : * worker is our worker identifier. Follows the general convention that
308 : : * -1 value relates to a leader tuplesort, and values >= 0 worker
309 : : * tuplesorts. (-1 can also be a serial tuplesort.)
310 : : *
311 : : * shared is mutable shared memory state, which is used to coordinate
312 : : * parallel sorts.
313 : : *
314 : : * nParticipants is the number of worker Tuplesortstates known by the
315 : : * leader to have actually been launched, which implies that they must
316 : : * finish a run that the leader needs to merge. Typically includes a
317 : : * worker state held by the leader process itself. Set in the leader
318 : : * Tuplesortstate only.
319 : : */
320 : : int worker;
321 : : Sharedsort *shared;
322 : : int nParticipants;
323 : :
324 : : /*
325 : : * Additional state for managing "abbreviated key" sortsupport routines
326 : : * (which currently may be used by all cases except the hash index case).
327 : : * Tracks the intervals at which the optimization's effectiveness is
328 : : * tested.
329 : : */
330 : : int64 abbrevNext; /* Tuple # at which to next check
331 : : * applicability */
332 : :
333 : : /*
334 : : * Resource snapshot for time of sort start.
335 : : */
336 : : PGRUsage ru_start;
337 : : };
338 : :
339 : : /*
340 : : * Private mutable state of tuplesort-parallel-operation. This is allocated
341 : : * in shared memory.
342 : : */
343 : : struct Sharedsort
344 : : {
345 : : /* mutex protects all fields prior to tapes */
346 : : slock_t mutex;
347 : :
348 : : /*
349 : : * currentWorker generates ordinal identifier numbers for parallel sort
350 : : * workers. These start from 0, and are always gapless.
351 : : *
352 : : * Workers increment workersFinished to indicate having finished. If this
353 : : * is equal to state.nParticipants within the leader, leader is ready to
354 : : * merge worker runs.
355 : : */
356 : : int currentWorker;
357 : : int workersFinished;
358 : :
359 : : /* Temporary file space */
360 : : SharedFileSet fileset;
361 : :
362 : : /* Size of tapes flexible array */
363 : : int nTapes;
364 : :
365 : : /*
366 : : * Tapes array used by workers to report back information needed by the
367 : : * leader to concatenate all worker tapes into one for merging
368 : : */
369 : : TapeShare tapes[FLEXIBLE_ARRAY_MEMBER];
370 : : };
371 : :
372 : : /*
373 : : * Is the given tuple allocated from the slab memory arena?
374 : : */
375 : : #define IS_SLAB_SLOT(state, tuple) \
376 : : ((char *) (tuple) >= (state)->slabMemoryBegin && \
377 : : (char *) (tuple) < (state)->slabMemoryEnd)
378 : :
379 : : /*
380 : : * Return the given tuple to the slab memory free list, or free it
381 : : * if it was palloc'd.
382 : : */
383 : : #define RELEASE_SLAB_SLOT(state, tuple) \
384 : : do { \
385 : : SlabSlot *buf = (SlabSlot *) tuple; \
386 : : \
387 : : if (IS_SLAB_SLOT((state), buf)) \
388 : : { \
389 : : buf->nextfree = (state)->slabFreeHead; \
390 : : (state)->slabFreeHead = buf; \
391 : : } else \
392 : : pfree(buf); \
393 : : } while(0)
394 : :
395 : : #define REMOVEABBREV(state,stup,count) ((*(state)->base.removeabbrev) (state, stup, count))
396 : : #define COMPARETUP(state,a,b) ((*(state)->base.comparetup) (a, b, state))
397 : : #define WRITETUP(state,tape,stup) ((*(state)->base.writetup) (state, tape, stup))
398 : : #define READTUP(state,stup,tape,len) ((*(state)->base.readtup) (state, stup, tape, len))
399 : : #define FREESTATE(state) ((state)->base.freestate ? (*(state)->base.freestate) (state) : (void) 0)
400 : : #define LACKMEM(state) ((state)->availMem < 0 && !(state)->slabAllocatorUsed)
401 : : #define USEMEM(state,amt) ((state)->availMem -= (amt))
402 : : #define FREEMEM(state,amt) ((state)->availMem += (amt))
403 : : #define SERIAL(state) ((state)->shared == NULL)
404 : : #define WORKER(state) ((state)->shared && (state)->worker != -1)
405 : : #define LEADER(state) ((state)->shared && (state)->worker == -1)
406 : :
407 : : /*
408 : : * NOTES about on-tape representation of tuples:
409 : : *
410 : : * We require the first "unsigned int" of a stored tuple to be the total size
411 : : * on-tape of the tuple, including itself (so it is never zero; an all-zero
412 : : * unsigned int is used to delimit runs). The remainder of the stored tuple
413 : : * may or may not match the in-memory representation of the tuple ---
414 : : * any conversion needed is the job of the writetup and readtup routines.
415 : : *
416 : : * If state->sortopt contains TUPLESORT_RANDOMACCESS, then the stored
417 : : * representation of the tuple must be followed by another "unsigned int" that
418 : : * is a copy of the length --- so the total tape space used is actually
419 : : * sizeof(unsigned int) more than the stored length value. This allows
420 : : * read-backwards. When the random access flag was not specified, the
421 : : * write/read routines may omit the extra length word.
422 : : *
423 : : * writetup is expected to write both length words as well as the tuple
424 : : * data. When readtup is called, the tape is positioned just after the
425 : : * front length word; readtup must read the tuple data and advance past
426 : : * the back length word (if present).
427 : : *
428 : : * The write/read routines can make use of the tuple description data
429 : : * stored in the Tuplesortstate record, if needed. They are also expected
430 : : * to adjust state->availMem by the amount of memory space (not tape space!)
431 : : * released or consumed. There is no error return from either writetup
432 : : * or readtup; they should ereport() on failure.
433 : : *
434 : : *
435 : : * NOTES about memory consumption calculations:
436 : : *
437 : : * We count space allocated for tuples against the workMem limit, plus
438 : : * the space used by the variable-size memtuples array. Fixed-size space
439 : : * is not counted; it's small enough to not be interesting.
440 : : *
441 : : * Note that we count actual space used (as shown by GetMemoryChunkSpace)
442 : : * rather than the originally-requested size. This is important since
443 : : * palloc can add substantial overhead. It's not a complete answer since
444 : : * we won't count any wasted space in palloc allocation blocks, but it's
445 : : * a lot better than what we were doing before 7.3. As of 9.6, a
446 : : * separate memory context is used for caller passed tuples. Resetting
447 : : * it at certain key increments significantly ameliorates fragmentation.
448 : : * readtup routines use the slab allocator (they cannot use
449 : : * the reset context because it gets deleted at the point that merging
450 : : * begins).
451 : : */
452 : :
453 : :
454 : : static void tuplesort_begin_batch(Tuplesortstate *state);
455 : : static bool consider_abort_common(Tuplesortstate *state);
456 : : static void inittapes(Tuplesortstate *state, bool mergeruns);
457 : : static void inittapestate(Tuplesortstate *state, int maxTapes);
458 : : static void selectnewtape(Tuplesortstate *state);
459 : : static void init_slab_allocator(Tuplesortstate *state, int numSlots);
460 : : static void mergeruns(Tuplesortstate *state);
461 : : static void mergeonerun(Tuplesortstate *state);
462 : : static void beginmerge(Tuplesortstate *state);
463 : : static bool mergereadnext(Tuplesortstate *state, LogicalTape *srcTape, SortTuple *stup);
464 : : static void dumptuples(Tuplesortstate *state, bool alltuples);
465 : : static void make_bounded_heap(Tuplesortstate *state);
466 : : static void sort_bounded_heap(Tuplesortstate *state);
467 : : static void tuplesort_sort_memtuples(Tuplesortstate *state);
468 : : static void tuplesort_heap_insert(Tuplesortstate *state, SortTuple *tuple);
469 : : static void tuplesort_heap_replace_top(Tuplesortstate *state, SortTuple *tuple);
470 : : static void tuplesort_heap_delete_top(Tuplesortstate *state);
471 : : static void reversedirection(Tuplesortstate *state);
472 : : static unsigned int getlen(LogicalTape *tape, bool eofOK);
473 : : static void markrunend(LogicalTape *tape);
474 : : static int worker_get_identifier(Tuplesortstate *state);
475 : : static void worker_freeze_result_tape(Tuplesortstate *state);
476 : : static void worker_nomergeruns(Tuplesortstate *state);
477 : : static void leader_takeover_tapes(Tuplesortstate *state);
478 : : static void free_sort_tuple(Tuplesortstate *state, SortTuple *stup);
479 : : static void tuplesort_free(Tuplesortstate *state);
480 : : static void tuplesort_updatemax(Tuplesortstate *state);
481 : :
482 : : /*
483 : : * Specialized comparators that we can inline into specialized sorts. The goal
484 : : * is to try to sort two tuples without having to follow the pointers to the
485 : : * comparator or the tuple.
486 : : *
487 : : * XXX: For now, there is no specialization for cases where datum1 is
488 : : * authoritative and we don't even need to fall back to a callback at all (that
489 : : * would be true for types like int4/int8/timestamp/date, but not true for
490 : : * abbreviations of text or multi-key sorts. There could be! Is it worth it?
491 : : */
492 : :
493 : : /* Used if first key's comparator is ssup_datum_unsigned_cmp */
494 : : static pg_attribute_always_inline int
1305 john.naylor@postgres 495 :CBC 23272162 : qsort_tuple_unsigned_compare(SortTuple *a, SortTuple *b, Tuplesortstate *state)
496 : : {
497 : : int compare;
498 : :
499 : 23272162 : compare = ApplyUnsignedSortComparator(a->datum1, a->isnull1,
500 : 23272162 : b->datum1, b->isnull1,
501 : : &state->base.sortKeys[0]);
502 [ + + ]: 23272162 : if (compare != 0)
503 : 20988753 : return compare;
504 : :
505 : : /*
506 : : * No need to waste effort calling the tiebreak function when there are no
507 : : * other keys to sort on.
508 : : */
1189 akorotkov@postgresql 509 [ - + ]: 2283409 : if (state->base.onlyKey != NULL)
1285 drowley@postgresql.o 510 :UBC 0 : return 0;
511 : :
804 john.naylor@postgres 512 :CBC 2283409 : return state->base.comparetup_tiebreak(a, b, state);
513 : : }
514 : :
515 : : /* Used if first key's comparator is ssup_datum_signed_cmp */
516 : : static pg_attribute_always_inline int
1305 517 : 4812541 : qsort_tuple_signed_compare(SortTuple *a, SortTuple *b, Tuplesortstate *state)
518 : : {
519 : : int compare;
520 : :
521 : 4812541 : compare = ApplySignedSortComparator(a->datum1, a->isnull1,
522 : 4812541 : b->datum1, b->isnull1,
523 : : &state->base.sortKeys[0]);
524 : :
525 [ + + ]: 4812541 : if (compare != 0)
526 : 4759018 : return compare;
527 : :
528 : : /*
529 : : * No need to waste effort calling the tiebreak function when there are no
530 : : * other keys to sort on.
531 : : */
1189 akorotkov@postgresql 532 [ + + ]: 53523 : if (state->base.onlyKey != NULL)
1285 drowley@postgresql.o 533 : 46279 : return 0;
534 : :
804 john.naylor@postgres 535 : 7244 : return state->base.comparetup_tiebreak(a, b, state);
536 : : }
537 : :
538 : : /* Used if first key's comparator is ssup_datum_int32_cmp */
539 : : static pg_attribute_always_inline int
1305 540 : 28072621 : qsort_tuple_int32_compare(SortTuple *a, SortTuple *b, Tuplesortstate *state)
541 : : {
542 : : int compare;
543 : :
544 : 28072621 : compare = ApplyInt32SortComparator(a->datum1, a->isnull1,
1265 tgl@sss.pgh.pa.us 545 : 28072621 : b->datum1, b->isnull1,
546 : : &state->base.sortKeys[0]);
547 : :
1305 john.naylor@postgres 548 [ + + ]: 28072621 : if (compare != 0)
549 : 20083371 : return compare;
550 : :
551 : : /*
552 : : * No need to waste effort calling the tiebreak function when there are no
553 : : * other keys to sort on.
554 : : */
1189 akorotkov@postgresql 555 [ + + ]: 7989250 : if (state->base.onlyKey != NULL)
1285 drowley@postgresql.o 556 : 1137696 : return 0;
557 : :
804 john.naylor@postgres 558 : 6851554 : return state->base.comparetup_tiebreak(a, b, state);
559 : : }
560 : :
561 : : /*
562 : : * Special versions of qsort just for SortTuple objects. qsort_tuple() sorts
563 : : * any variant of SortTuples, using the appropriate comparetup function.
564 : : * qsort_ssup() is specialized for the case where the comparetup function
565 : : * reduces to ApplySortComparator(), that is single-key MinimalTuple sorts
566 : : * and Datum sorts. qsort_tuple_{unsigned,signed,int32} are specialized for
567 : : * common comparison functions on pass-by-value leading datums.
568 : : */
569 : :
570 : : #define ST_SORT qsort_tuple_unsigned
571 : : #define ST_ELEMENT_TYPE SortTuple
572 : : #define ST_COMPARE(a, b, state) qsort_tuple_unsigned_compare(a, b, state)
573 : : #define ST_COMPARE_ARG_TYPE Tuplesortstate
574 : : #define ST_CHECK_FOR_INTERRUPTS
575 : : #define ST_SCOPE static
576 : : #define ST_DEFINE
577 : : #include "lib/sort_template.h"
578 : :
579 : : #define ST_SORT qsort_tuple_signed
580 : : #define ST_ELEMENT_TYPE SortTuple
581 : : #define ST_COMPARE(a, b, state) qsort_tuple_signed_compare(a, b, state)
582 : : #define ST_COMPARE_ARG_TYPE Tuplesortstate
583 : : #define ST_CHECK_FOR_INTERRUPTS
584 : : #define ST_SCOPE static
585 : : #define ST_DEFINE
586 : : #include "lib/sort_template.h"
587 : :
588 : : #define ST_SORT qsort_tuple_int32
589 : : #define ST_ELEMENT_TYPE SortTuple
590 : : #define ST_COMPARE(a, b, state) qsort_tuple_int32_compare(a, b, state)
591 : : #define ST_COMPARE_ARG_TYPE Tuplesortstate
592 : : #define ST_CHECK_FOR_INTERRUPTS
593 : : #define ST_SCOPE static
594 : : #define ST_DEFINE
595 : : #include "lib/sort_template.h"
596 : :
597 : : #define ST_SORT qsort_tuple
598 : : #define ST_ELEMENT_TYPE SortTuple
599 : : #define ST_COMPARE_RUNTIME_POINTER
600 : : #define ST_COMPARE_ARG_TYPE Tuplesortstate
601 : : #define ST_CHECK_FOR_INTERRUPTS
602 : : #define ST_SCOPE static
603 : : #define ST_DECLARE
604 : : #define ST_DEFINE
605 : : #include "lib/sort_template.h"
606 : :
607 : : #define ST_SORT qsort_ssup
608 : : #define ST_ELEMENT_TYPE SortTuple
609 : : #define ST_COMPARE(a, b, ssup) \
610 : : ApplySortComparator((a)->datum1, (a)->isnull1, \
611 : : (b)->datum1, (b)->isnull1, (ssup))
612 : : #define ST_COMPARE_ARG_TYPE SortSupportData
613 : : #define ST_CHECK_FOR_INTERRUPTS
614 : : #define ST_SCOPE static
615 : : #define ST_DEFINE
616 : : #include "lib/sort_template.h"
617 : :
618 : : /*
619 : : * tuplesort_begin_xxx
620 : : *
621 : : * Initialize for a tuple sort operation.
622 : : *
623 : : * After calling tuplesort_begin, the caller should call tuplesort_putXXX
624 : : * zero or more times, then call tuplesort_performsort when all the tuples
625 : : * have been supplied. After performsort, retrieve the tuples in sorted
626 : : * order by calling tuplesort_getXXX until it returns false/NULL. (If random
627 : : * access was requested, rescan, markpos, and restorepos can also be called.)
628 : : * Call tuplesort_end to terminate the operation and release memory/disk space.
629 : : *
630 : : * Each variant of tuplesort_begin has a workMem parameter specifying the
631 : : * maximum number of kilobytes of RAM to use before spilling data to disk.
632 : : * (The normal value of this parameter is work_mem, but some callers use
633 : : * other values.) Each variant also has a sortopt which is a bitmask of
634 : : * sort options. See TUPLESORT_* definitions in tuplesort.h
635 : : */
636 : :
637 : : Tuplesortstate *
1303 drowley@postgresql.o 638 : 136662 : tuplesort_begin_common(int workMem, SortCoordinate coordinate, int sortopt)
639 : : {
640 : : Tuplesortstate *state;
641 : : MemoryContext maincontext;
642 : : MemoryContext sortcontext;
643 : : MemoryContext oldcontext;
644 : :
645 : : /* See leader_takeover_tapes() remarks on random access support */
646 [ + + - + ]: 136662 : if (coordinate && (sortopt & TUPLESORT_RANDOMACCESS))
2825 rhaas@postgresql.org 647 [ # # ]:UBC 0 : elog(ERROR, "random access disallowed under parallel sort");
648 : :
649 : : /*
650 : : * Memory context surviving tuplesort_reset. This memory context holds
651 : : * data which is useful to keep while sorting multiple similar batches.
652 : : */
2031 tomas.vondra@postgre 653 :CBC 136662 : maincontext = AllocSetContextCreate(CurrentMemoryContext,
654 : : "TupleSort main",
655 : : ALLOCSET_DEFAULT_SIZES);
656 : :
657 : : /*
658 : : * Create a working memory context for one sort operation. The content of
659 : : * this context is deleted by tuplesort_reset.
660 : : */
661 : 136662 : sortcontext = AllocSetContextCreate(maincontext,
662 : : "TupleSort sort",
663 : : ALLOCSET_DEFAULT_SIZES);
664 : :
665 : : /*
666 : : * Additionally a working memory context for tuples is setup in
667 : : * tuplesort_begin_batch.
668 : : */
669 : :
670 : : /*
671 : : * Make the Tuplesortstate within the per-sortstate context. This way, we
672 : : * don't need a separate pfree() operation for it at shutdown.
673 : : */
674 : 136662 : oldcontext = MemoryContextSwitchTo(maincontext);
675 : :
8385 bruce@momjian.us 676 : 136662 : state = (Tuplesortstate *) palloc0(sizeof(Tuplesortstate));
677 : :
7330 tgl@sss.pgh.pa.us 678 [ - + ]: 136662 : if (trace_sort)
7330 tgl@sss.pgh.pa.us 679 :UBC 0 : pg_rusage_init(&state->ru_start);
680 : :
1189 akorotkov@postgresql 681 :CBC 136662 : state->base.sortopt = sortopt;
682 : 136662 : state->base.tuples = true;
683 : 136662 : state->abbrevNext = 10;
684 : :
685 : : /*
686 : : * workMem is forced to be at least 64KB, the current minimum valid value
687 : : * for the work_mem GUC. This is a defense against parallel sort callers
688 : : * that divide out memory among many workers in a way that leaves each
689 : : * with very little memory.
690 : : */
2825 rhaas@postgresql.org 691 : 136662 : state->allowedMem = Max(workMem, 64) * (int64) 1024;
1189 akorotkov@postgresql 692 : 136662 : state->base.sortcontext = sortcontext;
693 : 136662 : state->base.maincontext = maincontext;
694 : :
695 : : /*
696 : : * Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
697 : : * see comments in grow_memtuples().
698 : : */
2031 tomas.vondra@postgre 699 : 136662 : state->memtupsize = INITIAL_MEMTUPSIZE;
700 : 136662 : state->memtuples = NULL;
701 : :
702 : : /*
703 : : * After all of the other non-parallel-related state, we setup all of the
704 : : * state needed for each batch.
705 : : */
706 : 136662 : tuplesort_begin_batch(state);
707 : :
708 : : /*
709 : : * Initialize parallel-related state based on coordination information
710 : : * from caller
711 : : */
2825 rhaas@postgresql.org 712 [ + + ]: 136662 : if (!coordinate)
713 : : {
714 : : /* Serial sort */
715 : 136330 : state->shared = NULL;
716 : 136330 : state->worker = -1;
717 : 136330 : state->nParticipants = -1;
718 : : }
719 [ + + ]: 332 : else if (coordinate->isWorker)
720 : : {
721 : : /* Parallel worker produces exactly one final run from all input */
722 : 222 : state->shared = coordinate->sharedsort;
723 : 222 : state->worker = worker_get_identifier(state);
724 : 222 : state->nParticipants = -1;
725 : : }
726 : : else
727 : : {
728 : : /* Parallel leader state only used for final merge */
729 : 110 : state->shared = coordinate->sharedsort;
730 : 110 : state->worker = -1;
731 : 110 : state->nParticipants = coordinate->nParticipants;
732 [ - + ]: 110 : Assert(state->nParticipants >= 1);
733 : : }
734 : :
7184 tgl@sss.pgh.pa.us 735 : 136662 : MemoryContextSwitchTo(oldcontext);
736 : :
9508 737 : 136662 : return state;
738 : : }
739 : :
740 : : /*
741 : : * tuplesort_begin_batch
742 : : *
743 : : * Setup, or reset, all state need for processing a new set of tuples with this
744 : : * sort state. Called both from tuplesort_begin_common (the first time sorting
745 : : * with this sort state) and tuplesort_reset (for subsequent usages).
746 : : */
747 : : static void
2031 tomas.vondra@postgre 748 : 138332 : tuplesort_begin_batch(Tuplesortstate *state)
749 : : {
750 : : MemoryContext oldcontext;
751 : :
1189 akorotkov@postgresql 752 : 138332 : oldcontext = MemoryContextSwitchTo(state->base.maincontext);
753 : :
754 : : /*
755 : : * Caller tuple (e.g. IndexTuple) memory context.
756 : : *
757 : : * A dedicated child context used exclusively for caller passed tuples
758 : : * eases memory management. Resetting at key points reduces
759 : : * fragmentation. Note that the memtuples array of SortTuples is allocated
760 : : * in the parent context, not this context, because there is no need to
761 : : * free memtuples early. For bounded sorts, tuples may be pfreed in any
762 : : * order, so we use a regular aset.c context so that it can make use of
763 : : * free'd memory. When the sort is not bounded, we make use of a bump.c
764 : : * context as this keeps allocations more compact with less wastage.
765 : : * Allocations are also slightly more CPU efficient.
766 : : */
568 drowley@postgresql.o 767 [ + + ]: 138332 : if (TupleSortUseBumpTupleCxt(state->base.sortopt))
768 : 137646 : state->base.tuplecontext = BumpContextCreate(state->base.sortcontext,
769 : : "Caller tuples",
770 : : ALLOCSET_DEFAULT_SIZES);
771 : : else
1189 akorotkov@postgresql 772 : 686 : state->base.tuplecontext = AllocSetContextCreate(state->base.sortcontext,
773 : : "Caller tuples",
774 : : ALLOCSET_DEFAULT_SIZES);
775 : :
776 : :
2031 tomas.vondra@postgre 777 : 138332 : state->status = TSS_INITIAL;
778 : 138332 : state->bounded = false;
779 : 138332 : state->boundUsed = false;
780 : :
781 : 138332 : state->availMem = state->allowedMem;
782 : :
783 : 138332 : state->tapeset = NULL;
784 : :
785 : 138332 : state->memtupcount = 0;
786 : :
787 : : /*
788 : : * Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
789 : : * see comments in grow_memtuples().
790 : : */
791 : 138332 : state->growmemtuples = true;
792 : 138332 : state->slabAllocatorUsed = false;
793 [ + + + + ]: 138332 : if (state->memtuples != NULL && state->memtupsize != INITIAL_MEMTUPSIZE)
794 : : {
2031 tomas.vondra@postgre 795 :GBC 36 : pfree(state->memtuples);
796 : 36 : state->memtuples = NULL;
797 : 36 : state->memtupsize = INITIAL_MEMTUPSIZE;
798 : : }
2031 tomas.vondra@postgre 799 [ + + ]:CBC 138332 : if (state->memtuples == NULL)
800 : : {
801 : 136698 : state->memtuples = (SortTuple *) palloc(state->memtupsize * sizeof(SortTuple));
802 : 136698 : USEMEM(state, GetMemoryChunkSpace(state->memtuples));
803 : : }
804 : :
805 : : /* workMem must be large enough for the minimal memtuples array */
806 [ - + - - ]: 138332 : if (LACKMEM(state))
2031 tomas.vondra@postgre 807 [ # # ]:UBC 0 : elog(ERROR, "insufficient memory allowed for sort");
808 : :
2031 tomas.vondra@postgre 809 :CBC 138332 : state->currentRun = 0;
810 : :
811 : : /*
812 : : * Tape variables (inputTapes, outputTapes, etc.) will be initialized by
813 : : * inittapes(), if needed.
814 : : */
815 : :
1471 heikki.linnakangas@i 816 : 138332 : state->result_tape = NULL; /* flag that result tape has not been formed */
817 : :
2031 tomas.vondra@postgre 818 : 138332 : MemoryContextSwitchTo(oldcontext);
819 : 138332 : }
820 : :
821 : : /*
822 : : * tuplesort_set_bound
823 : : *
824 : : * Advise tuplesort that at most the first N result tuples are required.
825 : : *
826 : : * Must be called before inserting any tuples. (Actually, we could allow it
827 : : * as long as the sort hasn't spilled to disk, but there seems no need for
828 : : * delayed calls at the moment.)
829 : : *
830 : : * This is a hint only. The tuplesort may still return more tuples than
831 : : * requested. Parallel leader tuplesorts will always ignore the hint.
832 : : */
833 : : void
6752 tgl@sss.pgh.pa.us 834 : 619 : tuplesort_set_bound(Tuplesortstate *state, int64 bound)
835 : : {
836 : : /* Assert we're called before loading any tuples */
2238 alvherre@alvh.no-ip. 837 [ + - - + ]: 619 : Assert(state->status == TSS_INITIAL && state->memtupcount == 0);
838 : : /* Assert we allow bounded sorts */
1189 akorotkov@postgresql 839 [ - + ]: 619 : Assert(state->base.sortopt & TUPLESORT_ALLOWBOUNDED);
840 : : /* Can't set the bound twice, either */
6752 tgl@sss.pgh.pa.us 841 [ - + ]: 619 : Assert(!state->bounded);
842 : : /* Also, this shouldn't be called in a parallel worker */
2825 rhaas@postgresql.org 843 [ - + - - ]: 619 : Assert(!WORKER(state));
844 : :
845 : : /* Parallel leader allows but ignores hint */
2237 tgl@sss.pgh.pa.us 846 [ - + - - ]: 619 : if (LEADER(state))
2237 tgl@sss.pgh.pa.us 847 :UBC 0 : return;
848 : :
849 : : #ifdef DEBUG_BOUNDED_SORT
850 : : /* Honor GUC setting that disables the feature (for easy testing) */
851 : : if (!optimize_bounded_sort)
852 : : return;
853 : : #endif
854 : :
855 : : /* We want to be able to compute bound * 2, so limit the setting */
6557 bruce@momjian.us 856 [ - + ]:CBC 619 : if (bound > (int64) (INT_MAX / 2))
6752 tgl@sss.pgh.pa.us 857 :UBC 0 : return;
858 : :
6752 tgl@sss.pgh.pa.us 859 :CBC 619 : state->bounded = true;
860 : 619 : state->bound = (int) bound;
861 : :
862 : : /*
863 : : * Bounded sorts are not an effective target for abbreviated key
864 : : * optimization. Disable by setting state to be consistent with no
865 : : * abbreviation support.
866 : : */
1189 akorotkov@postgresql 867 : 619 : state->base.sortKeys->abbrev_converter = NULL;
868 [ + + ]: 619 : if (state->base.sortKeys->abbrev_full_comparator)
869 : 8 : state->base.sortKeys->comparator = state->base.sortKeys->abbrev_full_comparator;
870 : :
871 : : /* Not strictly necessary, but be tidy */
872 : 619 : state->base.sortKeys->abbrev_abort = NULL;
873 : 619 : state->base.sortKeys->abbrev_full_comparator = NULL;
874 : : }
875 : :
876 : : /*
877 : : * tuplesort_used_bound
878 : : *
879 : : * Allow callers to find out if the sort state was able to use a bound.
880 : : */
881 : : bool
2031 tomas.vondra@postgre 882 : 190 : tuplesort_used_bound(Tuplesortstate *state)
883 : : {
884 : 190 : return state->boundUsed;
885 : : }
886 : :
887 : : /*
888 : : * tuplesort_free
889 : : *
890 : : * Internal routine for freeing resources of tuplesort.
891 : : */
892 : : static void
893 : 138201 : tuplesort_free(Tuplesortstate *state)
894 : : {
895 : : /* context swap probably not needed, but let's be safe */
1189 akorotkov@postgresql 896 : 138201 : MemoryContext oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
897 : : int64 spaceUsed;
898 : :
9508 tgl@sss.pgh.pa.us 899 [ + + ]: 138201 : if (state->tapeset)
7315 900 : 369 : spaceUsed = LogicalTapeSetBlocks(state->tapeset);
901 : : else
902 : 137832 : spaceUsed = (state->allowedMem - state->availMem + 1023) / 1024;
903 : :
904 : : /*
905 : : * Delete temporary "tape" files, if any.
906 : : *
907 : : * We don't bother to destroy the individual tapes here. They will go away
908 : : * with the sortcontext. (In TSS_FINALMERGE state, we have closed
909 : : * finished tapes already.)
910 : : */
7184 911 [ + + ]: 138201 : if (state->tapeset)
912 : 369 : LogicalTapeSetClose(state->tapeset);
913 : :
7330 914 [ - + ]: 138201 : if (trace_sort)
915 : : {
7315 tgl@sss.pgh.pa.us 916 [ # # ]:UBC 0 : if (state->tapeset)
213 peter@eisentraut.org 917 [ # # # # ]: 0 : elog(LOG, "%s of worker %d ended, %" PRId64 " disk blocks used: %s",
918 : : SERIAL(state) ? "external sort" : "parallel external sort",
919 : : state->worker, spaceUsed, pg_rusage_show(&state->ru_start));
920 : : else
921 [ # # # # ]: 0 : elog(LOG, "%s of worker %d ended, %" PRId64 " KB used: %s",
922 : : SERIAL(state) ? "internal sort" : "unperformed parallel sort",
923 : : state->worker, spaceUsed, pg_rusage_show(&state->ru_start));
924 : : }
925 : :
926 : : TRACE_POSTGRESQL_SORT_DONE(state->tapeset != NULL, spaceUsed);
927 : :
1189 akorotkov@postgresql 928 [ + + ]:CBC 138201 : FREESTATE(state);
7184 tgl@sss.pgh.pa.us 929 : 138201 : MemoryContextSwitchTo(oldcontext);
930 : :
931 : : /*
932 : : * Free the per-sort memory context, thereby releasing all working memory.
933 : : */
1189 akorotkov@postgresql 934 : 138201 : MemoryContextReset(state->base.sortcontext);
2031 tomas.vondra@postgre 935 : 138201 : }
936 : :
937 : : /*
938 : : * tuplesort_end
939 : : *
940 : : * Release resources and clean up.
941 : : *
942 : : * NOTE: after calling this, any pointers returned by tuplesort_getXXX are
943 : : * pointing to garbage. Be careful not to attempt to use or free such
944 : : * pointers afterwards!
945 : : */
946 : : void
947 : 136531 : tuplesort_end(Tuplesortstate *state)
948 : : {
949 : 136531 : tuplesort_free(state);
950 : :
951 : : /*
952 : : * Free the main memory context, including the Tuplesortstate struct
953 : : * itself.
954 : : */
1189 akorotkov@postgresql 955 : 136531 : MemoryContextDelete(state->base.maincontext);
2031 tomas.vondra@postgre 956 : 136531 : }
957 : :
958 : : /*
959 : : * tuplesort_updatemax
960 : : *
961 : : * Update maximum resource usage statistics.
962 : : */
963 : : static void
964 : 1868 : tuplesort_updatemax(Tuplesortstate *state)
965 : : {
966 : : int64 spaceUsed;
967 : : bool isSpaceDisk;
968 : :
969 : : /*
970 : : * Note: it might seem we should provide both memory and disk usage for a
971 : : * disk-based sort. However, the current code doesn't track memory space
972 : : * accurately once we have begun to return tuples to the caller (since we
973 : : * don't account for pfree's the caller is expected to do), so we cannot
974 : : * rely on availMem in a disk sort. This does not seem worth the overhead
975 : : * to fix. Is it worth creating an API for the memory context code to
976 : : * tell us how much is actually used in sortcontext?
977 : : */
978 [ + + ]: 1868 : if (state->tapeset)
979 : : {
980 : 3 : isSpaceDisk = true;
981 : 3 : spaceUsed = LogicalTapeSetBlocks(state->tapeset) * BLCKSZ;
982 : : }
983 : : else
984 : : {
985 : 1865 : isSpaceDisk = false;
986 : 1865 : spaceUsed = state->allowedMem - state->availMem;
987 : : }
988 : :
989 : : /*
990 : : * Sort evicts data to the disk when it wasn't able to fit that data into
991 : : * main memory. This is why we assume space used on the disk to be more
992 : : * important for tracking resource usage than space used in memory. Note
993 : : * that the amount of space occupied by some tupleset on the disk might be
994 : : * less than amount of space occupied by the same tupleset in memory due
995 : : * to more compact representation.
996 : : */
997 [ + + - + ]: 1868 : if ((isSpaceDisk && !state->isMaxSpaceDisk) ||
998 [ + - + + ]: 1865 : (isSpaceDisk == state->isMaxSpaceDisk && spaceUsed > state->maxSpace))
999 : : {
1000 : 253 : state->maxSpace = spaceUsed;
1001 : 253 : state->isMaxSpaceDisk = isSpaceDisk;
1002 : 253 : state->maxSpaceStatus = state->status;
1003 : : }
1004 : 1868 : }
1005 : :
1006 : : /*
1007 : : * tuplesort_reset
1008 : : *
1009 : : * Reset the tuplesort. Reset all the data in the tuplesort, but leave the
1010 : : * meta-information in. After tuplesort_reset, tuplesort is ready to start
1011 : : * a new sort. This allows avoiding recreation of tuple sort states (and
1012 : : * save resources) when sorting multiple small batches.
1013 : : */
1014 : : void
1015 : 1670 : tuplesort_reset(Tuplesortstate *state)
1016 : : {
1017 : 1670 : tuplesort_updatemax(state);
1018 : 1670 : tuplesort_free(state);
1019 : :
1020 : : /*
1021 : : * After we've freed up per-batch memory, re-setup all of the state common
1022 : : * to both the first batch and any subsequent batch.
1023 : : */
1024 : 1670 : tuplesort_begin_batch(state);
1025 : :
1026 : 1670 : state->lastReturnedTuple = NULL;
1027 : 1670 : state->slabMemoryBegin = NULL;
1028 : 1670 : state->slabMemoryEnd = NULL;
1029 : 1670 : state->slabFreeHead = NULL;
7184 tgl@sss.pgh.pa.us 1030 : 1670 : }
1031 : :
1032 : : /*
1033 : : * Grow the memtuples[] array, if possible within our memory constraint. We
1034 : : * must not exceed INT_MAX tuples in memory or the caller-provided memory
1035 : : * limit. Return true if we were able to enlarge the array, false if not.
1036 : : *
1037 : : * Normally, at each increment we double the size of the array. When doing
1038 : : * that would exceed a limit, we attempt one last, smaller increase (and then
1039 : : * clear the growmemtuples flag so we don't try any more). That allows us to
1040 : : * use memory as fully as permitted; sticking to the pure doubling rule could
1041 : : * result in almost half going unused. Because availMem moves around with
1042 : : * tuple addition/removal, we need some rule to prevent making repeated small
1043 : : * increases in memtupsize, which would just be useless thrashing. The
1044 : : * growmemtuples flag accomplishes that and also prevents useless
1045 : : * recalculations in this function.
1046 : : */
1047 : : static bool
1048 : 4274 : grow_memtuples(Tuplesortstate *state)
1049 : : {
1050 : : int newmemtupsize;
4667 1051 : 4274 : int memtupsize = state->memtupsize;
4499 noah@leadboat.com 1052 : 4274 : int64 memNowUsed = state->allowedMem - state->availMem;
1053 : :
1054 : : /* Forget it if we've already maxed out memtuples, per comment above */
4667 tgl@sss.pgh.pa.us 1055 [ + + ]: 4274 : if (!state->growmemtuples)
1056 : 69 : return false;
1057 : :
1058 : : /* Select new value of memtupsize */
1059 [ + + ]: 4205 : if (memNowUsed <= state->availMem)
1060 : : {
1061 : : /*
1062 : : * We've used no more than half of allowedMem; double our usage,
1063 : : * clamping at INT_MAX tuples.
1064 : : */
4506 noah@leadboat.com 1065 [ + - ]: 4134 : if (memtupsize < INT_MAX / 2)
1066 : 4134 : newmemtupsize = memtupsize * 2;
1067 : : else
1068 : : {
4506 noah@leadboat.com 1069 :UBC 0 : newmemtupsize = INT_MAX;
1070 : 0 : state->growmemtuples = false;
1071 : : }
1072 : : }
1073 : : else
1074 : : {
1075 : : /*
1076 : : * This will be the last increment of memtupsize. Abandon doubling
1077 : : * strategy and instead increase as much as we safely can.
1078 : : *
1079 : : * To stay within allowedMem, we can't increase memtupsize by more
1080 : : * than availMem / sizeof(SortTuple) elements. In practice, we want
1081 : : * to increase it by considerably less, because we need to leave some
1082 : : * space for the tuples to which the new array slots will refer. We
1083 : : * assume the new tuples will be about the same size as the tuples
1084 : : * we've already seen, and thus we can extrapolate from the space
1085 : : * consumption so far to estimate an appropriate new size for the
1086 : : * memtuples array. The optimal value might be higher or lower than
1087 : : * this estimate, but it's hard to know that in advance. We again
1088 : : * clamp at INT_MAX tuples.
1089 : : *
1090 : : * This calculation is safe against enlarging the array so much that
1091 : : * LACKMEM becomes true, because the memory currently used includes
1092 : : * the present array; thus, there would be enough allowedMem for the
1093 : : * new array elements even if no other memory were currently used.
1094 : : *
1095 : : * We do the arithmetic in float8, because otherwise the product of
1096 : : * memtupsize and allowedMem could overflow. Any inaccuracy in the
1097 : : * result should be insignificant; but even if we computed a
1098 : : * completely insane result, the checks below will prevent anything
1099 : : * really bad from happening.
1100 : : */
1101 : : double grow_ratio;
1102 : :
4667 tgl@sss.pgh.pa.us 1103 :CBC 71 : grow_ratio = (double) state->allowedMem / (double) memNowUsed;
4506 noah@leadboat.com 1104 [ + - ]: 71 : if (memtupsize * grow_ratio < INT_MAX)
1105 : 71 : newmemtupsize = (int) (memtupsize * grow_ratio);
1106 : : else
4506 noah@leadboat.com 1107 :UBC 0 : newmemtupsize = INT_MAX;
1108 : :
1109 : : /* We won't make any further enlargement attempts */
4667 tgl@sss.pgh.pa.us 1110 :CBC 71 : state->growmemtuples = false;
1111 : : }
1112 : :
1113 : : /* Must enlarge array by at least one element, else report failure */
1114 [ - + ]: 4205 : if (newmemtupsize <= memtupsize)
4667 tgl@sss.pgh.pa.us 1115 :UBC 0 : goto noalloc;
1116 : :
1117 : : /*
1118 : : * On a 32-bit machine, allowedMem could exceed MaxAllocHugeSize. Clamp
1119 : : * to ensure our request won't be rejected. Note that we can easily
1120 : : * exhaust address space before facing this outcome. (This is presently
1121 : : * impossible due to guc.c's MAX_KILOBYTES limitation on work_mem, but
1122 : : * don't rely on that at this distance.)
1123 : : */
4506 noah@leadboat.com 1124 [ - + ]:CBC 4205 : if ((Size) newmemtupsize >= MaxAllocHugeSize / sizeof(SortTuple))
1125 : : {
4506 noah@leadboat.com 1126 :UBC 0 : newmemtupsize = (int) (MaxAllocHugeSize / sizeof(SortTuple));
4667 tgl@sss.pgh.pa.us 1127 : 0 : state->growmemtuples = false; /* can't grow any more */
1128 : : }
1129 : :
1130 : : /*
1131 : : * We need to be sure that we do not cause LACKMEM to become true, else
1132 : : * the space management algorithm will go nuts. The code above should
1133 : : * never generate a dangerous request, but to be safe, check explicitly
1134 : : * that the array growth fits within availMem. (We could still cause
1135 : : * LACKMEM if the memory chunk overhead associated with the memtuples
1136 : : * array were to increase. That shouldn't happen because we chose the
1137 : : * initial array size large enough to ensure that palloc will be treating
1138 : : * both old and new arrays as separate chunks. But we'll check LACKMEM
1139 : : * explicitly below just in case.)
1140 : : */
4499 noah@leadboat.com 1141 [ - + ]:CBC 4205 : if (state->availMem < (int64) ((newmemtupsize - memtupsize) * sizeof(SortTuple)))
4667 tgl@sss.pgh.pa.us 1142 :UBC 0 : goto noalloc;
1143 : :
1144 : : /* OK, do it */
7184 tgl@sss.pgh.pa.us 1145 :CBC 4205 : FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
4667 1146 : 4205 : state->memtupsize = newmemtupsize;
7184 1147 : 4205 : state->memtuples = (SortTuple *)
4506 noah@leadboat.com 1148 : 4205 : repalloc_huge(state->memtuples,
1149 : 4205 : state->memtupsize * sizeof(SortTuple));
7184 tgl@sss.pgh.pa.us 1150 : 4205 : USEMEM(state, GetMemoryChunkSpace(state->memtuples));
1151 [ - + - - ]: 4205 : if (LACKMEM(state))
3738 tgl@sss.pgh.pa.us 1152 [ # # ]:UBC 0 : elog(ERROR, "unexpected out-of-memory situation in tuplesort");
7184 tgl@sss.pgh.pa.us 1153 :CBC 4205 : return true;
1154 : :
4667 tgl@sss.pgh.pa.us 1155 :UBC 0 : noalloc:
1156 : : /* If for any reason we didn't realloc, shut off future attempts */
1157 : 0 : state->growmemtuples = false;
1158 : 0 : return false;
1159 : : }
1160 : :
1161 : : /*
1162 : : * Shared code for tuple and datum cases.
1163 : : */
1164 : : void
568 drowley@postgresql.o 1165 :CBC 15543811 : tuplesort_puttuple_common(Tuplesortstate *state, SortTuple *tuple,
1166 : : bool useAbbrev, Size tuplen)
1167 : : {
1189 akorotkov@postgresql 1168 : 15543811 : MemoryContext oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
1169 : :
2825 rhaas@postgresql.org 1170 [ + + - + ]: 15543811 : Assert(!LEADER(state));
1171 : :
1172 : : /* account for the memory used for this tuple */
568 drowley@postgresql.o 1173 : 15543811 : USEMEM(state, tuplen);
1174 : 15543811 : state->tupleMem += tuplen;
1175 : :
1189 akorotkov@postgresql 1176 [ + + ]: 15543811 : if (!useAbbrev)
1177 : : {
1178 : : /*
1179 : : * Leave ordinary Datum representation, or NULL value. If there is a
1180 : : * converter it won't expect NULL values, and cost model is not
1181 : : * required to account for NULL, so in that case we avoid calling
1182 : : * converter and just set datum1 to zeroed representation (to be
1183 : : * consistent, and to support cheap inequality tests for NULL
1184 : : * abbreviated keys).
1185 : : */
1186 : : }
1187 [ + + ]: 2217695 : else if (!consider_abort_common(state))
1188 : : {
1189 : : /* Store abbreviated key representation */
1190 : 2217647 : tuple->datum1 = state->base.sortKeys->abbrev_converter(tuple->datum1,
1191 : : state->base.sortKeys);
1192 : : }
1193 : : else
1194 : : {
1195 : : /*
1196 : : * Set state to be consistent with never trying abbreviation.
1197 : : *
1198 : : * Alter datum1 representation in already-copied tuples, so as to
1199 : : * ensure a consistent representation (current tuple was just
1200 : : * handled). It does not matter if some dumped tuples are already
1201 : : * sorted on tape, since serialized tuples lack abbreviated keys
1202 : : * (TSS_BUILDRUNS state prevents control reaching here in any case).
1203 : : */
1204 : 48 : REMOVEABBREV(state, state->memtuples, state->memtupcount);
1205 : : }
1206 : :
9508 tgl@sss.pgh.pa.us 1207 [ + + + - ]: 15543811 : switch (state->status)
1208 : : {
8769 bruce@momjian.us 1209 : 13119337 : case TSS_INITIAL:
1210 : :
1211 : : /*
1212 : : * Save the tuple into the unsorted array. First, grow the array
1213 : : * as needed. Note that we try to grow the array when there is
1214 : : * still one free slot remaining --- if we fail, there'll still be
1215 : : * room to store the incoming tuple, and then we'll switch to
1216 : : * tape-based operation.
1217 : : */
7184 tgl@sss.pgh.pa.us 1218 [ + + ]: 13119337 : if (state->memtupcount >= state->memtupsize - 1)
1219 : : {
1220 : 4274 : (void) grow_memtuples(state);
1221 [ - + ]: 4274 : Assert(state->memtupcount < state->memtupsize);
1222 : : }
1223 : 13119337 : state->memtuples[state->memtupcount++] = *tuple;
1224 : :
1225 : : /*
1226 : : * Check if it's time to switch over to a bounded heapsort. We do
1227 : : * so if the input tuple count exceeds twice the desired tuple
1228 : : * count (this is a heuristic for where heapsort becomes cheaper
1229 : : * than a quicksort), or if we've just filled workMem and have
1230 : : * enough tuples to meet the bound.
1231 : : *
1232 : : * Note that once we enter TSS_BOUNDED state we will always try to
1233 : : * complete the sort that way. In the worst case, if later input
1234 : : * tuples are larger than earlier ones, this might cause us to
1235 : : * exceed workMem significantly.
1236 : : */
6752 1237 [ + + ]: 13119337 : if (state->bounded &&
1238 [ + + ]: 32201 : (state->memtupcount > state->bound * 2 ||
1239 [ + + - + : 31991 : (state->memtupcount > state->bound && LACKMEM(state))))
- - ]
1240 : : {
1241 [ - + ]: 210 : if (trace_sort)
6752 tgl@sss.pgh.pa.us 1242 [ # # ]:UBC 0 : elog(LOG, "switching to bounded heapsort at %d tuples: %s",
1243 : : state->memtupcount,
1244 : : pg_rusage_show(&state->ru_start));
6752 tgl@sss.pgh.pa.us 1245 :CBC 210 : make_bounded_heap(state);
1189 akorotkov@postgresql 1246 : 210 : MemoryContextSwitchTo(oldcontext);
6752 tgl@sss.pgh.pa.us 1247 : 210 : return;
1248 : : }
1249 : :
1250 : : /*
1251 : : * Done if we still fit in available memory and have array slots.
1252 : : */
7184 1253 [ + + - + : 13119127 : if (state->memtupcount < state->memtupsize && !LACKMEM(state))
- - ]
1254 : : {
1189 akorotkov@postgresql 1255 : 13119058 : MemoryContextSwitchTo(oldcontext);
9508 tgl@sss.pgh.pa.us 1256 : 13119058 : return;
1257 : : }
1258 : :
1259 : : /*
1260 : : * Nope; time to switch to tape-based operation.
1261 : : */
2825 rhaas@postgresql.org 1262 : 69 : inittapes(state, true);
1263 : :
1264 : : /*
1265 : : * Dump all tuples.
1266 : : */
9508 tgl@sss.pgh.pa.us 1267 : 69 : dumptuples(state, false);
1268 : 69 : break;
1269 : :
6752 1270 : 1870538 : case TSS_BOUNDED:
1271 : :
1272 : : /*
1273 : : * We don't want to grow the array here, so check whether the new
1274 : : * tuple can be discarded before putting it in. This should be a
1275 : : * good speed optimization, too, since when there are many more
1276 : : * input tuples than the bound, most input tuples can be discarded
1277 : : * with just this one comparison. Note that because we currently
1278 : : * have the sort direction reversed, we must check for <= not >=.
1279 : : */
1280 [ + + ]: 1870538 : if (COMPARETUP(state, tuple, &state->memtuples[0]) <= 0)
1281 : : {
1282 : : /* new tuple <= top of the heap, so we can discard it */
1283 : 1619275 : free_sort_tuple(state, tuple);
4970 rhaas@postgresql.org 1284 [ + + ]: 1619275 : CHECK_FOR_INTERRUPTS();
1285 : : }
1286 : : else
1287 : : {
1288 : : /* discard top of heap, replacing it with the new tuple */
6752 tgl@sss.pgh.pa.us 1289 : 251263 : free_sort_tuple(state, &state->memtuples[0]);
2951 rhaas@postgresql.org 1290 : 251263 : tuplesort_heap_replace_top(state, tuple);
1291 : : }
6752 tgl@sss.pgh.pa.us 1292 : 1870538 : break;
1293 : :
9508 1294 : 553936 : case TSS_BUILDRUNS:
1295 : :
1296 : : /*
1297 : : * Save the tuple into the unsorted array (there must be space)
1298 : : */
2951 rhaas@postgresql.org 1299 : 553936 : state->memtuples[state->memtupcount++] = *tuple;
1300 : :
1301 : : /*
1302 : : * If we are over the memory limit, dump all tuples.
1303 : : */
9508 tgl@sss.pgh.pa.us 1304 : 553936 : dumptuples(state, false);
1305 : 553936 : break;
1306 : :
9508 tgl@sss.pgh.pa.us 1307 :UBC 0 : default:
8131 1308 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
1309 : : break;
1310 : : }
1189 akorotkov@postgresql 1311 :CBC 2424543 : MemoryContextSwitchTo(oldcontext);
1312 : : }
1313 : :
1314 : : static bool
3935 rhaas@postgresql.org 1315 : 2217695 : consider_abort_common(Tuplesortstate *state)
1316 : : {
1189 akorotkov@postgresql 1317 [ - + ]: 2217695 : Assert(state->base.sortKeys[0].abbrev_converter != NULL);
1318 [ - + ]: 2217695 : Assert(state->base.sortKeys[0].abbrev_abort != NULL);
1319 [ - + ]: 2217695 : Assert(state->base.sortKeys[0].abbrev_full_comparator != NULL);
1320 : :
1321 : : /*
1322 : : * Check effectiveness of abbreviation optimization. Consider aborting
1323 : : * when still within memory limit.
1324 : : */
3935 rhaas@postgresql.org 1325 [ + + ]: 2217695 : if (state->status == TSS_INITIAL &&
1326 [ + + ]: 1981465 : state->memtupcount >= state->abbrevNext)
1327 : : {
1328 : 2510 : state->abbrevNext *= 2;
1329 : :
1330 : : /*
1331 : : * Check opclass-supplied abbreviation abort routine. It may indicate
1332 : : * that abbreviation should not proceed.
1333 : : */
1189 akorotkov@postgresql 1334 [ + + ]: 2510 : if (!state->base.sortKeys->abbrev_abort(state->memtupcount,
1335 : : state->base.sortKeys))
3935 rhaas@postgresql.org 1336 : 2462 : return false;
1337 : :
1338 : : /*
1339 : : * Finally, restore authoritative comparator, and indicate that
1340 : : * abbreviation is not in play by setting abbrev_converter to NULL
1341 : : */
1189 akorotkov@postgresql 1342 : 48 : state->base.sortKeys[0].comparator = state->base.sortKeys[0].abbrev_full_comparator;
1343 : 48 : state->base.sortKeys[0].abbrev_converter = NULL;
1344 : : /* Not strictly necessary, but be tidy */
1345 : 48 : state->base.sortKeys[0].abbrev_abort = NULL;
1346 : 48 : state->base.sortKeys[0].abbrev_full_comparator = NULL;
1347 : :
1348 : : /* Give up - expect original pass-by-value representation */
3935 rhaas@postgresql.org 1349 : 48 : return true;
1350 : : }
1351 : :
1352 : 2215185 : return false;
1353 : : }
1354 : :
1355 : : /*
1356 : : * All tuples have been provided; finish the sort.
1357 : : */
1358 : : void
9508 tgl@sss.pgh.pa.us 1359 : 117467 : tuplesort_performsort(Tuplesortstate *state)
1360 : : {
1189 akorotkov@postgresql 1361 : 117467 : MemoryContext oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
1362 : :
7330 tgl@sss.pgh.pa.us 1363 [ - + ]: 117467 : if (trace_sort)
2553 pg@bowt.ie 1364 [ # # ]:UBC 0 : elog(LOG, "performsort of worker %d starting: %s",
1365 : : state->worker, pg_rusage_show(&state->ru_start));
1366 : :
9508 tgl@sss.pgh.pa.us 1367 [ + + + - ]:CBC 117467 : switch (state->status)
1368 : : {
8769 bruce@momjian.us 1369 : 117188 : case TSS_INITIAL:
1370 : :
1371 : : /*
1372 : : * We were able to accumulate all the tuples within the allowed
1373 : : * amount of memory, or leader to take over worker tapes
1374 : : */
2825 rhaas@postgresql.org 1375 [ + + ]: 117188 : if (SERIAL(state))
1376 : : {
1377 : : /* Just qsort 'em and we're done */
1378 : 116888 : tuplesort_sort_memtuples(state);
1379 : 116843 : state->status = TSS_SORTEDINMEM;
1380 : : }
1381 [ + - + + ]: 300 : else if (WORKER(state))
1382 : : {
1383 : : /*
1384 : : * Parallel workers must still dump out tuples to tape. No
1385 : : * merge is required to produce single output run, though.
1386 : : */
1387 : 222 : inittapes(state, false);
1388 : 222 : dumptuples(state, true);
1389 : 222 : worker_nomergeruns(state);
1390 : 222 : state->status = TSS_SORTEDONTAPE;
1391 : : }
1392 : : else
1393 : : {
1394 : : /*
1395 : : * Leader will take over worker tapes and merge worker runs.
1396 : : * Note that mergeruns sets the correct state->status.
1397 : : */
1398 : 78 : leader_takeover_tapes(state);
1399 : 78 : mergeruns(state);
1400 : : }
9508 tgl@sss.pgh.pa.us 1401 : 117143 : state->current = 0;
1402 : 117143 : state->eof_reached = false;
2825 rhaas@postgresql.org 1403 : 117143 : state->markpos_block = 0L;
9508 tgl@sss.pgh.pa.us 1404 : 117143 : state->markpos_offset = 0;
1405 : 117143 : state->markpos_eof = false;
1406 : 117143 : break;
1407 : :
6752 1408 : 210 : case TSS_BOUNDED:
1409 : :
1410 : : /*
1411 : : * We were able to accumulate all the tuples required for output
1412 : : * in memory, using a heap to eliminate excess tuples. Now we
1413 : : * have to transform the heap to a properly-sorted array. Note
1414 : : * that sort_bounded_heap sets the correct state->status.
1415 : : */
6632 1416 : 210 : sort_bounded_heap(state);
6752 1417 : 210 : state->current = 0;
1418 : 210 : state->eof_reached = false;
1419 : 210 : state->markpos_offset = 0;
1420 : 210 : state->markpos_eof = false;
1421 : 210 : break;
1422 : :
9508 1423 : 69 : case TSS_BUILDRUNS:
1424 : :
1425 : : /*
1426 : : * Finish tape-based sort. First, flush all tuples remaining in
1427 : : * memory out to tape; then merge until we have a single remaining
1428 : : * run (or, if !randomAccess and !WORKER(), one run per tape).
1429 : : * Note that mergeruns sets the correct state->status.
1430 : : */
1431 : 69 : dumptuples(state, true);
1432 : 69 : mergeruns(state);
1433 : 69 : state->eof_reached = false;
1434 : 69 : state->markpos_block = 0L;
1435 : 69 : state->markpos_offset = 0;
1436 : 69 : state->markpos_eof = false;
1437 : 69 : break;
1438 : :
9508 tgl@sss.pgh.pa.us 1439 :UBC 0 : default:
8131 1440 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
1441 : : break;
1442 : : }
1443 : :
7330 tgl@sss.pgh.pa.us 1444 [ - + ]:CBC 117422 : if (trace_sort)
1445 : : {
7174 tgl@sss.pgh.pa.us 1446 [ # # ]:UBC 0 : if (state->status == TSS_FINALMERGE)
2553 pg@bowt.ie 1447 [ # # ]: 0 : elog(LOG, "performsort of worker %d done (except %d-way final merge): %s",
1448 : : state->worker, state->nInputTapes,
1449 : : pg_rusage_show(&state->ru_start));
1450 : : else
1451 [ # # ]: 0 : elog(LOG, "performsort of worker %d done: %s",
1452 : : state->worker, pg_rusage_show(&state->ru_start));
1453 : : }
1454 : :
7184 tgl@sss.pgh.pa.us 1455 :CBC 117422 : MemoryContextSwitchTo(oldcontext);
9508 1456 : 117422 : }
1457 : :
1458 : : /*
1459 : : * Internal routine to fetch the next tuple in either forward or back
1460 : : * direction into *stup. Returns false if no more tuples.
1461 : : * Returned tuple belongs to tuplesort memory context, and must not be freed
1462 : : * by caller. Note that fetched tuple is stored in memory that may be
1463 : : * recycled by any future fetch.
1464 : : */
1465 : : bool
7184 1466 : 14298128 : tuplesort_gettuple_common(Tuplesortstate *state, bool forward,
1467 : : SortTuple *stup)
1468 : : {
1469 : : unsigned int tuplen;
1470 : : size_t nmoved;
1471 : :
2825 rhaas@postgresql.org 1472 [ + + - + ]: 14298128 : Assert(!WORKER(state));
1473 : :
9508 tgl@sss.pgh.pa.us 1474 [ + + + - ]: 14298128 : switch (state->status)
1475 : : {
1476 : 11834310 : case TSS_SORTEDINMEM:
1189 akorotkov@postgresql 1477 [ + + - + ]: 11834310 : Assert(forward || state->base.sortopt & TUPLESORT_RANDOMACCESS);
3312 heikki.linnakangas@i 1478 [ - + ]: 11834310 : Assert(!state->slabAllocatorUsed);
9508 tgl@sss.pgh.pa.us 1479 [ + + ]: 11834310 : if (forward)
1480 : : {
1481 [ + + ]: 11834277 : if (state->current < state->memtupcount)
1482 : : {
7184 1483 : 11717876 : *stup = state->memtuples[state->current++];
1484 : 11717876 : return true;
1485 : : }
9508 1486 : 116401 : state->eof_reached = true;
1487 : :
1488 : : /*
1489 : : * Complain if caller tries to retrieve more tuples than
1490 : : * originally asked for in a bounded sort. This is because
1491 : : * returning EOF here might be the wrong thing.
1492 : : */
6752 1493 [ + + - + ]: 116401 : if (state->bounded && state->current >= state->bound)
6752 tgl@sss.pgh.pa.us 1494 [ # # ]:UBC 0 : elog(ERROR, "retrieved too many tuples in a bounded sort");
1495 : :
7184 tgl@sss.pgh.pa.us 1496 :CBC 116401 : return false;
1497 : : }
1498 : : else
1499 : : {
9508 1500 [ - + ]: 33 : if (state->current <= 0)
7184 tgl@sss.pgh.pa.us 1501 :UBC 0 : return false;
1502 : :
1503 : : /*
1504 : : * if all tuples are fetched already then we return last
1505 : : * tuple, else - tuple before last returned.
1506 : : */
9508 tgl@sss.pgh.pa.us 1507 [ + + ]:CBC 33 : if (state->eof_reached)
1508 : 6 : state->eof_reached = false;
1509 : : else
1510 : : {
9330 bruce@momjian.us 1511 : 27 : state->current--; /* last returned tuple */
9508 tgl@sss.pgh.pa.us 1512 [ + + ]: 27 : if (state->current <= 0)
7184 1513 : 3 : return false;
1514 : : }
1515 : 30 : *stup = state->memtuples[state->current - 1];
1516 : 30 : return true;
1517 : : }
1518 : : break;
1519 : :
9508 1520 : 141498 : case TSS_SORTEDONTAPE:
1189 akorotkov@postgresql 1521 [ + + - + ]: 141498 : Assert(forward || state->base.sortopt & TUPLESORT_RANDOMACCESS);
3312 heikki.linnakangas@i 1522 [ - + ]: 141498 : Assert(state->slabAllocatorUsed);
1523 : :
1524 : : /*
1525 : : * The slot that held the tuple that we returned in previous
1526 : : * gettuple call can now be reused.
1527 : : */
1528 [ + + ]: 141498 : if (state->lastReturnedTuple)
1529 : : {
1530 [ + - + - ]: 76425 : RELEASE_SLAB_SLOT(state, state->lastReturnedTuple);
1531 : 76425 : state->lastReturnedTuple = NULL;
1532 : : }
1533 : :
9508 tgl@sss.pgh.pa.us 1534 [ + + ]: 141498 : if (forward)
1535 : : {
1536 [ - + ]: 141483 : if (state->eof_reached)
7184 tgl@sss.pgh.pa.us 1537 :UBC 0 : return false;
1538 : :
1471 heikki.linnakangas@i 1539 [ + + ]:CBC 141483 : if ((tuplen = getlen(state->result_tape, true)) != 0)
1540 : : {
7184 tgl@sss.pgh.pa.us 1541 : 141470 : READTUP(state, stup, state->result_tape, tuplen);
1542 : :
1543 : : /*
1544 : : * Remember the tuple we return, so that we can recycle
1545 : : * its memory on next call. (This can be NULL, in the
1546 : : * !state->tuples case).
1547 : : */
3312 heikki.linnakangas@i 1548 : 141470 : state->lastReturnedTuple = stup->tuple;
1549 : :
7184 tgl@sss.pgh.pa.us 1550 : 141470 : return true;
1551 : : }
1552 : : else
1553 : : {
9508 1554 : 13 : state->eof_reached = true;
7184 1555 : 13 : return false;
1556 : : }
1557 : : }
1558 : :
1559 : : /*
1560 : : * Backward.
1561 : : *
1562 : : * if all tuples are fetched already then we return last tuple,
1563 : : * else - tuple before last returned.
1564 : : */
9508 1565 [ + + ]: 15 : if (state->eof_reached)
1566 : : {
1567 : : /*
1568 : : * Seek position is pointing just past the zero tuplen at the
1569 : : * end of file; back up to fetch last tuple's ending length
1570 : : * word. If seek fails we must have a completely empty file.
1571 : : */
1471 heikki.linnakangas@i 1572 : 6 : nmoved = LogicalTapeBackspace(state->result_tape,
1573 : : 2 * sizeof(unsigned int));
3232 1574 [ - + ]: 6 : if (nmoved == 0)
7184 tgl@sss.pgh.pa.us 1575 :UBC 0 : return false;
3232 heikki.linnakangas@i 1576 [ - + ]:CBC 6 : else if (nmoved != 2 * sizeof(unsigned int))
3232 heikki.linnakangas@i 1577 [ # # ]:UBC 0 : elog(ERROR, "unexpected tape position");
9508 tgl@sss.pgh.pa.us 1578 :CBC 6 : state->eof_reached = false;
1579 : : }
1580 : : else
1581 : : {
1582 : : /*
1583 : : * Back up and fetch previously-returned tuple's ending length
1584 : : * word. If seek fails, assume we are at start of file.
1585 : : */
1471 heikki.linnakangas@i 1586 : 9 : nmoved = LogicalTapeBackspace(state->result_tape,
1587 : : sizeof(unsigned int));
3232 1588 [ - + ]: 9 : if (nmoved == 0)
7184 tgl@sss.pgh.pa.us 1589 :UBC 0 : return false;
3232 heikki.linnakangas@i 1590 [ - + ]:CBC 9 : else if (nmoved != sizeof(unsigned int))
3232 heikki.linnakangas@i 1591 [ # # ]:UBC 0 : elog(ERROR, "unexpected tape position");
1471 heikki.linnakangas@i 1592 :CBC 9 : tuplen = getlen(state->result_tape, false);
1593 : :
1594 : : /*
1595 : : * Back up to get ending length word of tuple before it.
1596 : : */
1597 : 9 : nmoved = LogicalTapeBackspace(state->result_tape,
1598 : : tuplen + 2 * sizeof(unsigned int));
3232 1599 [ + + ]: 9 : if (nmoved == tuplen + sizeof(unsigned int))
1600 : : {
1601 : : /*
1602 : : * We backed up over the previous tuple, but there was no
1603 : : * ending length word before it. That means that the prev
1604 : : * tuple is the first tuple in the file. It is now the
1605 : : * next to read in forward direction (not obviously right,
1606 : : * but that is what in-memory case does).
1607 : : */
7184 tgl@sss.pgh.pa.us 1608 : 3 : return false;
1609 : : }
3232 heikki.linnakangas@i 1610 [ - + ]: 6 : else if (nmoved != tuplen + 2 * sizeof(unsigned int))
3232 heikki.linnakangas@i 1611 [ # # ]:UBC 0 : elog(ERROR, "bogus tuple length in backward scan");
1612 : : }
1613 : :
1471 heikki.linnakangas@i 1614 :CBC 12 : tuplen = getlen(state->result_tape, false);
1615 : :
1616 : : /*
1617 : : * Now we have the length of the prior tuple, back up and read it.
1618 : : * Note: READTUP expects we are positioned after the initial
1619 : : * length word of the tuple, so back up to that point.
1620 : : */
1621 : 12 : nmoved = LogicalTapeBackspace(state->result_tape,
1622 : : tuplen);
3232 1623 [ - + ]: 12 : if (nmoved != tuplen)
8131 tgl@sss.pgh.pa.us 1624 [ # # ]:UBC 0 : elog(ERROR, "bogus tuple length in backward scan");
7184 tgl@sss.pgh.pa.us 1625 :CBC 12 : READTUP(state, stup, state->result_tape, tuplen);
1626 : :
1627 : : /*
1628 : : * Remember the tuple we return, so that we can recycle its memory
1629 : : * on next call. (This can be NULL, in the Datum case).
1630 : : */
3312 heikki.linnakangas@i 1631 : 12 : state->lastReturnedTuple = stup->tuple;
1632 : :
7184 tgl@sss.pgh.pa.us 1633 : 12 : return true;
1634 : :
9508 1635 : 2322320 : case TSS_FINALMERGE:
1636 [ - + ]: 2322320 : Assert(forward);
1637 : : /* We are managing memory ourselves, with the slab allocator. */
3312 heikki.linnakangas@i 1638 [ - + ]: 2322320 : Assert(state->slabAllocatorUsed);
1639 : :
1640 : : /*
1641 : : * The slab slot holding the tuple that we returned in previous
1642 : : * gettuple call can now be reused.
1643 : : */
1644 [ + + ]: 2322320 : if (state->lastReturnedTuple)
1645 : : {
1646 [ + - + - ]: 2262168 : RELEASE_SLAB_SLOT(state, state->lastReturnedTuple);
1647 : 2262168 : state->lastReturnedTuple = NULL;
1648 : : }
1649 : :
1650 : : /*
1651 : : * This code should match the inner loop of mergeonerun().
1652 : : */
9495 tgl@sss.pgh.pa.us 1653 [ + + ]: 2322320 : if (state->memtupcount > 0)
1654 : : {
1471 heikki.linnakangas@i 1655 : 2322192 : int srcTapeIndex = state->memtuples[0].srctape;
1656 : 2322192 : LogicalTape *srcTape = state->inputTapes[srcTapeIndex];
1657 : : SortTuple newtup;
1658 : :
3312 1659 : 2322192 : *stup = state->memtuples[0];
1660 : :
1661 : : /*
1662 : : * Remember the tuple we return, so that we can recycle its
1663 : : * memory on next call. (This can be NULL, in the Datum case).
1664 : : */
1665 : 2322192 : state->lastReturnedTuple = stup->tuple;
1666 : :
1667 : : /*
1668 : : * Pull next tuple from tape, and replace the returned tuple
1669 : : * at top of the heap with it.
1670 : : */
1671 [ + + ]: 2322192 : if (!mergereadnext(state, srcTape, &newtup))
1672 : : {
1673 : : /*
1674 : : * If no more data, we've reached end of run on this tape.
1675 : : * Remove the top node from the heap.
1676 : : */
2951 rhaas@postgresql.org 1677 : 197 : tuplesort_heap_delete_top(state);
1471 heikki.linnakangas@i 1678 : 197 : state->nInputRuns--;
1679 : :
1680 : : /*
1681 : : * Close the tape. It'd go away at the end of the sort
1682 : : * anyway, but better to release the memory early.
1683 : : */
1189 akorotkov@postgresql 1684 : 197 : LogicalTapeClose(srcTape);
1685 : 197 : return true;
1686 : : }
1687 : 2321995 : newtup.srctape = srcTapeIndex;
1688 : 2321995 : tuplesort_heap_replace_top(state, &newtup);
1689 : 2321995 : return true;
1690 : : }
1691 : 128 : return false;
1692 : :
1189 akorotkov@postgresql 1693 :UBC 0 : default:
1694 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
1695 : : return false; /* keep compiler quiet */
1696 : : }
1697 : : }
1698 : :
1699 : :
1700 : : /*
1701 : : * Advance over N tuples in either forward or back direction,
1702 : : * without returning any data. N==0 is a no-op.
1703 : : * Returns true if successful, false if ran out of tuples.
1704 : : */
1705 : : bool
4327 tgl@sss.pgh.pa.us 1706 :CBC 196 : tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples, bool forward)
1707 : : {
1708 : : MemoryContext oldcontext;
1709 : :
1710 : : /*
1711 : : * We don't actually support backwards skip yet, because no callers need
1712 : : * it. The API is designed to allow for that later, though.
1713 : : */
1714 [ - + ]: 196 : Assert(forward);
1715 [ - + ]: 196 : Assert(ntuples >= 0);
2825 rhaas@postgresql.org 1716 [ - + - - ]: 196 : Assert(!WORKER(state));
1717 : :
4327 tgl@sss.pgh.pa.us 1718 [ + + - ]: 196 : switch (state->status)
1719 : : {
1720 : 184 : case TSS_SORTEDINMEM:
1721 [ + - ]: 184 : if (state->memtupcount - state->current >= ntuples)
1722 : : {
1723 : 184 : state->current += ntuples;
1724 : 184 : return true;
1725 : : }
4327 tgl@sss.pgh.pa.us 1726 :UBC 0 : state->current = state->memtupcount;
1727 : 0 : state->eof_reached = true;
1728 : :
1729 : : /*
1730 : : * Complain if caller tries to retrieve more tuples than
1731 : : * originally asked for in a bounded sort. This is because
1732 : : * returning EOF here might be the wrong thing.
1733 : : */
1734 [ # # # # ]: 0 : if (state->bounded && state->current >= state->bound)
1735 [ # # ]: 0 : elog(ERROR, "retrieved too many tuples in a bounded sort");
1736 : :
1737 : 0 : return false;
1738 : :
4327 tgl@sss.pgh.pa.us 1739 :CBC 12 : case TSS_SORTEDONTAPE:
1740 : : case TSS_FINALMERGE:
1741 : :
1742 : : /*
1743 : : * We could probably optimize these cases better, but for now it's
1744 : : * not worth the trouble.
1745 : : */
1189 akorotkov@postgresql 1746 : 12 : oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
4327 tgl@sss.pgh.pa.us 1747 [ + + ]: 120066 : while (ntuples-- > 0)
1748 : : {
1749 : : SortTuple stup;
1750 : :
3242 rhaas@postgresql.org 1751 [ - + ]: 120054 : if (!tuplesort_gettuple_common(state, forward, &stup))
1752 : : {
4326 tgl@sss.pgh.pa.us 1753 :UBC 0 : MemoryContextSwitchTo(oldcontext);
4327 1754 : 0 : return false;
1755 : : }
4327 tgl@sss.pgh.pa.us 1756 [ - + ]:CBC 120054 : CHECK_FOR_INTERRUPTS();
1757 : : }
4326 1758 : 12 : MemoryContextSwitchTo(oldcontext);
4327 1759 : 12 : return true;
1760 : :
4327 tgl@sss.pgh.pa.us 1761 :UBC 0 : default:
1762 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
1763 : : return false; /* keep compiler quiet */
1764 : : }
1765 : : }
1766 : :
1767 : : /*
1768 : : * tuplesort_merge_order - report merge order we'll use for given memory
1769 : : * (note: "merge order" just means the number of input tapes in the merge).
1770 : : *
1771 : : * This is exported for use by the planner. allowedMem is in bytes.
1772 : : */
1773 : : int
4499 noah@leadboat.com 1774 :CBC 9378 : tuplesort_merge_order(int64 allowedMem)
1775 : : {
1776 : : int mOrder;
1777 : :
1778 : : /*----------
1779 : : * In the merge phase, we need buffer space for each input and output tape.
1780 : : * Each pass in the balanced merge algorithm reads from M input tapes, and
1781 : : * writes to N output tapes. Each tape consumes TAPE_BUFFER_OVERHEAD bytes
1782 : : * of memory. In addition to that, we want MERGE_BUFFER_SIZE workspace per
1783 : : * input tape.
1784 : : *
1785 : : * totalMem = M * (TAPE_BUFFER_OVERHEAD + MERGE_BUFFER_SIZE) +
1786 : : * N * TAPE_BUFFER_OVERHEAD
1787 : : *
1788 : : * Except for the last and next-to-last merge passes, where there can be
1789 : : * fewer tapes left to process, M = N. We choose M so that we have the
1790 : : * desired amount of memory available for the input buffers
1791 : : * (TAPE_BUFFER_OVERHEAD + MERGE_BUFFER_SIZE), given the total memory
1792 : : * available for the tape buffers (allowedMem).
1793 : : *
1794 : : * Note: you might be thinking we need to account for the memtuples[]
1795 : : * array in this calculation, but we effectively treat that as part of the
1796 : : * MERGE_BUFFER_SIZE workspace.
1797 : : *----------
1798 : : */
1471 heikki.linnakangas@i 1799 : 9378 : mOrder = allowedMem /
1800 : : (2 * TAPE_BUFFER_OVERHEAD + MERGE_BUFFER_SIZE);
1801 : :
1802 : : /*
1803 : : * Even in minimum memory, use at least a MINORDER merge. On the other
1804 : : * hand, even when we have lots of memory, do not use more than a MAXORDER
1805 : : * merge. Tapes are pretty cheap, but they're not entirely free. Each
1806 : : * additional tape reduces the amount of memory available to build runs,
1807 : : * which in turn can cause the same sort to need more runs, which makes
1808 : : * merging slower even if it can still be done in a single pass. Also,
1809 : : * high order merges are quite slow due to CPU cache effects; it can be
1810 : : * faster to pay the I/O cost of a multi-pass merge than to perform a
1811 : : * single merge pass across many hundreds of tapes.
1812 : : */
7184 tgl@sss.pgh.pa.us 1813 : 9378 : mOrder = Max(mOrder, MINORDER);
3269 rhaas@postgresql.org 1814 : 9378 : mOrder = Min(mOrder, MAXORDER);
1815 : :
7184 tgl@sss.pgh.pa.us 1816 : 9378 : return mOrder;
1817 : : }
1818 : :
1819 : : /*
1820 : : * Helper function to calculate how much memory to allocate for the read buffer
1821 : : * of each input tape in a merge pass.
1822 : : *
1823 : : * 'avail_mem' is the amount of memory available for the buffers of all the
1824 : : * tapes, both input and output.
1825 : : * 'nInputTapes' and 'nInputRuns' are the number of input tapes and runs.
1826 : : * 'maxOutputTapes' is the max. number of output tapes we should produce.
1827 : : */
1828 : : static int64
1471 heikki.linnakangas@i 1829 : 162 : merge_read_buffer_size(int64 avail_mem, int nInputTapes, int nInputRuns,
1830 : : int maxOutputTapes)
1831 : : {
1832 : : int nOutputRuns;
1833 : : int nOutputTapes;
1834 : :
1835 : : /*
1836 : : * How many output tapes will we produce in this pass?
1837 : : *
1838 : : * This is nInputRuns / nInputTapes, rounded up.
1839 : : */
1840 : 162 : nOutputRuns = (nInputRuns + nInputTapes - 1) / nInputTapes;
1841 : :
1842 : 162 : nOutputTapes = Min(nOutputRuns, maxOutputTapes);
1843 : :
1844 : : /*
1845 : : * Each output tape consumes TAPE_BUFFER_OVERHEAD bytes of memory. All
1846 : : * remaining memory is divided evenly between the input tapes.
1847 : : *
1848 : : * This also follows from the formula in tuplesort_merge_order, but here
1849 : : * we derive the input buffer size from the amount of memory available,
1850 : : * and M and N.
1851 : : */
1852 : 162 : return Max((avail_mem - TAPE_BUFFER_OVERHEAD * nOutputTapes) / nInputTapes, 0);
1853 : : }
1854 : :
1855 : : /*
1856 : : * inittapes - initialize for tape sorting.
1857 : : *
1858 : : * This is called only if we have found we won't sort in memory.
1859 : : */
1860 : : static void
2825 rhaas@postgresql.org 1861 : 291 : inittapes(Tuplesortstate *state, bool mergeruns)
1862 : : {
1863 [ + + - + ]: 291 : Assert(!LEADER(state));
1864 : :
1865 [ + + ]: 291 : if (mergeruns)
1866 : : {
1867 : : /* Compute number of input tapes to use when merging */
1471 heikki.linnakangas@i 1868 : 69 : state->maxTapes = tuplesort_merge_order(state->allowedMem);
1869 : : }
1870 : : else
1871 : : {
1872 : : /* Workers can sometimes produce single run, output without merge */
2825 rhaas@postgresql.org 1873 [ + - - + ]: 222 : Assert(WORKER(state));
1471 heikki.linnakangas@i 1874 : 222 : state->maxTapes = MINORDER;
1875 : : }
1876 : :
7330 tgl@sss.pgh.pa.us 1877 [ - + ]: 291 : if (trace_sort)
2553 pg@bowt.ie 1878 [ # # ]:UBC 0 : elog(LOG, "worker %d switching to external sort with %d tapes: %s",
1879 : : state->worker, state->maxTapes, pg_rusage_show(&state->ru_start));
1880 : :
1881 : : /* Create the tape set */
1471 heikki.linnakangas@i 1882 :CBC 291 : inittapestate(state, state->maxTapes);
2825 rhaas@postgresql.org 1883 : 291 : state->tapeset =
1471 heikki.linnakangas@i 1884 : 291 : LogicalTapeSetCreate(false,
2825 rhaas@postgresql.org 1885 [ + + ]: 291 : state->shared ? &state->shared->fileset : NULL,
1886 : : state->worker);
1887 : :
2951 1888 : 291 : state->currentRun = 0;
1889 : :
1890 : : /*
1891 : : * Initialize logical tape arrays.
1892 : : */
1471 heikki.linnakangas@i 1893 : 291 : state->inputTapes = NULL;
1894 : 291 : state->nInputTapes = 0;
1895 : 291 : state->nInputRuns = 0;
1896 : :
1897 : 291 : state->outputTapes = palloc0(state->maxTapes * sizeof(LogicalTape *));
1898 : 291 : state->nOutputTapes = 0;
1899 : 291 : state->nOutputRuns = 0;
1900 : :
9508 tgl@sss.pgh.pa.us 1901 : 291 : state->status = TSS_BUILDRUNS;
1902 : :
1471 heikki.linnakangas@i 1903 : 291 : selectnewtape(state);
9508 tgl@sss.pgh.pa.us 1904 : 291 : }
1905 : :
1906 : : /*
1907 : : * inittapestate - initialize generic tape management state
1908 : : */
1909 : : static void
2825 rhaas@postgresql.org 1910 : 369 : inittapestate(Tuplesortstate *state, int maxTapes)
1911 : : {
1912 : : int64 tapeSpace;
1913 : :
1914 : : /*
1915 : : * Decrease availMem to reflect the space needed for tape buffers; but
1916 : : * don't decrease it to the point that we have no room for tuples. (That
1917 : : * case is only likely to occur if sorting pass-by-value Datums; in all
1918 : : * other scenarios the memtuples[] array is unlikely to occupy more than
1919 : : * half of allowedMem. In the pass-by-value case it's not important to
1920 : : * account for tuple space, so we don't care if LACKMEM becomes
1921 : : * inaccurate.)
1922 : : */
1923 : 369 : tapeSpace = (int64) maxTapes * TAPE_BUFFER_OVERHEAD;
1924 : :
1925 [ + + ]: 369 : if (tapeSpace + GetMemoryChunkSpace(state->memtuples) < state->allowedMem)
1926 : 309 : USEMEM(state, tapeSpace);
1927 : :
1928 : : /*
1929 : : * Make sure that the temp file(s) underlying the tape set are created in
1930 : : * suitable temp tablespaces. For parallel sorts, this should have been
1931 : : * called already, but it doesn't matter if it is called a second time.
1932 : : */
1933 : 369 : PrepareTempTablespaces();
1934 : 369 : }
1935 : :
1936 : : /*
1937 : : * selectnewtape -- select next tape to output to.
1938 : : *
1939 : : * This is called after finishing a run when we know another run
1940 : : * must be started. This is used both when building the initial
1941 : : * runs, and during merge passes.
1942 : : */
1943 : : static void
9508 tgl@sss.pgh.pa.us 1944 : 841 : selectnewtape(Tuplesortstate *state)
1945 : : {
1946 : : /*
1947 : : * At the beginning of each merge pass, nOutputTapes and nOutputRuns are
1948 : : * both zero. On each call, we create a new output tape to hold the next
1949 : : * run, until maxTapes is reached. After that, we assign new runs to the
1950 : : * existing tapes in a round robin fashion.
1951 : : */
1464 heikki.linnakangas@i 1952 [ + + ]: 841 : if (state->nOutputTapes < state->maxTapes)
1953 : : {
1954 : : /* Create a new tape to hold the next run */
1471 1955 [ - + ]: 550 : Assert(state->outputTapes[state->nOutputRuns] == NULL);
1956 [ - + ]: 550 : Assert(state->nOutputRuns == state->nOutputTapes);
1957 : 550 : state->destTape = LogicalTapeCreate(state->tapeset);
1464 1958 : 550 : state->outputTapes[state->nOutputTapes] = state->destTape;
1471 1959 : 550 : state->nOutputTapes++;
1960 : 550 : state->nOutputRuns++;
1961 : : }
1962 : : else
1963 : : {
1964 : : /*
1965 : : * We have reached the max number of tapes. Append to an existing
1966 : : * tape.
1967 : : */
1968 : 291 : state->destTape = state->outputTapes[state->nOutputRuns % state->nOutputTapes];
1969 : 291 : state->nOutputRuns++;
1970 : : }
9508 tgl@sss.pgh.pa.us 1971 : 841 : }
1972 : :
1973 : : /*
1974 : : * Initialize the slab allocation arena, for the given number of slots.
1975 : : */
1976 : : static void
3312 heikki.linnakangas@i 1977 : 147 : init_slab_allocator(Tuplesortstate *state, int numSlots)
1978 : : {
1979 [ + + ]: 147 : if (numSlots > 0)
1980 : : {
1981 : : char *p;
1982 : : int i;
1983 : :
1984 : 134 : state->slabMemoryBegin = palloc(numSlots * SLAB_SLOT_SIZE);
1985 : 134 : state->slabMemoryEnd = state->slabMemoryBegin +
1986 : 134 : numSlots * SLAB_SLOT_SIZE;
1987 : 134 : state->slabFreeHead = (SlabSlot *) state->slabMemoryBegin;
1988 : 134 : USEMEM(state, numSlots * SLAB_SLOT_SIZE);
1989 : :
1990 : 134 : p = state->slabMemoryBegin;
1991 [ + + ]: 512 : for (i = 0; i < numSlots - 1; i++)
1992 : : {
1993 : 378 : ((SlabSlot *) p)->nextfree = (SlabSlot *) (p + SLAB_SLOT_SIZE);
1994 : 378 : p += SLAB_SLOT_SIZE;
1995 : : }
1996 : 134 : ((SlabSlot *) p)->nextfree = NULL;
1997 : : }
1998 : : else
1999 : : {
2000 : 13 : state->slabMemoryBegin = state->slabMemoryEnd = NULL;
2001 : 13 : state->slabFreeHead = NULL;
2002 : : }
2003 : 147 : state->slabAllocatorUsed = true;
2004 : 147 : }
2005 : :
2006 : : /*
2007 : : * mergeruns -- merge all the completed initial runs.
2008 : : *
2009 : : * This implements the Balanced k-Way Merge Algorithm. All input data has
2010 : : * already been written to initial runs on tape (see dumptuples).
2011 : : */
2012 : : static void
9508 tgl@sss.pgh.pa.us 2013 : 147 : mergeruns(Tuplesortstate *state)
2014 : : {
2015 : : int tapenum;
2016 : :
2017 [ - + ]: 147 : Assert(state->status == TSS_BUILDRUNS);
9495 2018 [ - + ]: 147 : Assert(state->memtupcount == 0);
2019 : :
1189 akorotkov@postgresql 2020 [ + + + + ]: 147 : if (state->base.sortKeys != NULL && state->base.sortKeys->abbrev_converter != NULL)
2021 : : {
2022 : : /*
2023 : : * If there are multiple runs to be merged, when we go to read back
2024 : : * tuples from disk, abbreviated keys will not have been stored, and
2025 : : * we don't care to regenerate them. Disable abbreviation from this
2026 : : * point on.
2027 : : */
2028 : 15 : state->base.sortKeys->abbrev_converter = NULL;
2029 : 15 : state->base.sortKeys->comparator = state->base.sortKeys->abbrev_full_comparator;
2030 : :
2031 : : /* Not strictly necessary, but be tidy */
2032 : 15 : state->base.sortKeys->abbrev_abort = NULL;
2033 : 15 : state->base.sortKeys->abbrev_full_comparator = NULL;
2034 : : }
2035 : :
2036 : : /*
2037 : : * Reset tuple memory. We've freed all the tuples that we previously
2038 : : * allocated. We will use the slab allocator from now on.
2039 : : */
2040 : 147 : MemoryContextResetOnly(state->base.tuplecontext);
2041 : :
2042 : : /*
2043 : : * We no longer need a large memtuples array. (We will allocate a smaller
2044 : : * one for the heap later.)
2045 : : */
3312 heikki.linnakangas@i 2046 : 147 : FREEMEM(state, GetMemoryChunkSpace(state->memtuples));
2047 : 147 : pfree(state->memtuples);
2048 : 147 : state->memtuples = NULL;
2049 : :
2050 : : /*
2051 : : * Initialize the slab allocator. We need one slab slot per input tape,
2052 : : * for the tuples in the heap, plus one to hold the tuple last returned
2053 : : * from tuplesort_gettuple. (If we're sorting pass-by-val Datums,
2054 : : * however, we don't need to do allocate anything.)
2055 : : *
2056 : : * In a multi-pass merge, we could shrink this allocation for the last
2057 : : * merge pass, if it has fewer tapes than previous passes, but we don't
2058 : : * bother.
2059 : : *
2060 : : * From this point on, we no longer use the USEMEM()/LACKMEM() mechanism
2061 : : * to track memory usage of individual tuples.
2062 : : */
1189 akorotkov@postgresql 2063 [ + + ]: 147 : if (state->base.tuples)
1471 heikki.linnakangas@i 2064 : 134 : init_slab_allocator(state, state->nOutputTapes + 1);
2065 : : else
3312 2066 : 13 : init_slab_allocator(state, 0);
2067 : :
2068 : : /*
2069 : : * Allocate a new 'memtuples' array, for the heap. It will hold one tuple
2070 : : * from each input tape.
2071 : : *
2072 : : * We could shrink this, too, between passes in a multi-pass merge, but we
2073 : : * don't bother. (The initial input tapes are still in outputTapes. The
2074 : : * number of input tapes will not increase between passes.)
2075 : : */
1471 2076 : 147 : state->memtupsize = state->nOutputTapes;
1189 akorotkov@postgresql 2077 : 294 : state->memtuples = (SortTuple *) MemoryContextAlloc(state->base.maincontext,
1471 heikki.linnakangas@i 2078 : 147 : state->nOutputTapes * sizeof(SortTuple));
3246 2079 : 147 : USEMEM(state, GetMemoryChunkSpace(state->memtuples));
2080 : :
2081 : : /*
2082 : : * Use all the remaining memory we have available for tape buffers among
2083 : : * all the input tapes. At the beginning of each merge pass, we will
2084 : : * divide this memory between the input and output tapes in the pass.
2085 : : */
1471 2086 : 147 : state->tape_buffer_mem = state->availMem;
1464 2087 : 147 : USEMEM(state, state->tape_buffer_mem);
3303 2088 [ - + ]: 147 : if (trace_sort)
1471 heikki.linnakangas@i 2089 [ # # ]:UBC 0 : elog(LOG, "worker %d using %zu KB of memory for tape buffers",
2090 : : state->worker, state->tape_buffer_mem / 1024);
2091 : :
2092 : : for (;;)
2093 : : {
2094 : : /*
2095 : : * On the first iteration, or if we have read all the runs from the
2096 : : * input tapes in a multi-pass merge, it's time to start a new pass.
2097 : : * Rewind all the output tapes, and make them inputs for the next
2098 : : * pass.
2099 : : */
1471 heikki.linnakangas@i 2100 [ + + ]:CBC 216 : if (state->nInputRuns == 0)
2101 : : {
2102 : : int64 input_buffer_size;
2103 : :
2104 : : /* Close the old, emptied, input tapes */
2105 [ + + ]: 162 : if (state->nInputTapes > 0)
2106 : : {
2107 [ + + ]: 105 : for (tapenum = 0; tapenum < state->nInputTapes; tapenum++)
2108 : 90 : LogicalTapeClose(state->inputTapes[tapenum]);
2109 : 15 : pfree(state->inputTapes);
2110 : : }
2111 : :
2112 : : /* Previous pass's outputs become next pass's inputs. */
2113 : 162 : state->inputTapes = state->outputTapes;
2114 : 162 : state->nInputTapes = state->nOutputTapes;
2115 : 162 : state->nInputRuns = state->nOutputRuns;
2116 : :
2117 : : /*
2118 : : * Reset output tape variables. The actual LogicalTapes will be
2119 : : * created as needed, here we only allocate the array to hold
2120 : : * them.
2121 : : */
2122 : 162 : state->outputTapes = palloc0(state->nInputTapes * sizeof(LogicalTape *));
2123 : 162 : state->nOutputTapes = 0;
2124 : 162 : state->nOutputRuns = 0;
2125 : :
2126 : : /*
2127 : : * Redistribute the memory allocated for tape buffers, among the
2128 : : * new input and output tapes.
2129 : : */
2130 : 162 : input_buffer_size = merge_read_buffer_size(state->tape_buffer_mem,
2131 : : state->nInputTapes,
2132 : : state->nInputRuns,
2133 : : state->maxTapes);
2134 : :
2135 [ - + ]: 162 : if (trace_sort)
1471 heikki.linnakangas@i 2136 [ # # ]:UBC 0 : elog(LOG, "starting merge pass of %d input runs on %d tapes, " INT64_FORMAT " KB of memory for each input tape: %s",
2137 : : state->nInputRuns, state->nInputTapes, input_buffer_size / 1024,
2138 : : pg_rusage_show(&state->ru_start));
2139 : :
2140 : : /* Prepare the new input tapes for merge pass. */
1471 heikki.linnakangas@i 2141 [ + + ]:CBC 638 : for (tapenum = 0; tapenum < state->nInputTapes; tapenum++)
2142 : 476 : LogicalTapeRewindForRead(state->inputTapes[tapenum], input_buffer_size);
2143 : :
2144 : : /*
2145 : : * If there's just one run left on each input tape, then only one
2146 : : * merge pass remains. If we don't have to produce a materialized
2147 : : * sorted tape, we can stop at this point and do the final merge
2148 : : * on-the-fly.
2149 : : */
1189 akorotkov@postgresql 2150 [ + + ]: 162 : if ((state->base.sortopt & TUPLESORT_RANDOMACCESS) == 0
1303 drowley@postgresql.o 2151 [ + + ]: 152 : && state->nInputRuns <= state->nInputTapes
1471 heikki.linnakangas@i 2152 [ + + + - ]: 137 : && !WORKER(state))
2153 : : {
2154 : : /* Tell logtape.c we won't be writing anymore */
7175 tgl@sss.pgh.pa.us 2155 : 137 : LogicalTapeSetForgetFreeSpace(state->tapeset);
2156 : : /* Initialize for the final merge pass */
3312 heikki.linnakangas@i 2157 : 137 : beginmerge(state);
9508 tgl@sss.pgh.pa.us 2158 : 137 : state->status = TSS_FINALMERGE;
2159 : 137 : return;
2160 : : }
2161 : : }
2162 : :
2163 : : /* Select an output tape */
1471 heikki.linnakangas@i 2164 : 79 : selectnewtape(state);
2165 : :
2166 : : /* Merge one run from each input tape. */
2167 : 79 : mergeonerun(state);
2168 : :
2169 : : /*
2170 : : * If the input tapes are empty, and we output only one output run,
2171 : : * we're done. The current output tape contains the final result.
2172 : : */
2173 [ + + + + ]: 79 : if (state->nInputRuns == 0 && state->nOutputRuns <= 1)
2174 : 10 : break;
2175 : : }
2176 : :
2177 : : /*
2178 : : * Done. The result is on a single run on a single tape.
2179 : : */
2180 : 10 : state->result_tape = state->outputTapes[0];
2825 rhaas@postgresql.org 2181 [ - + - - ]: 10 : if (!WORKER(state))
1471 heikki.linnakangas@i 2182 : 10 : LogicalTapeFreeze(state->result_tape, NULL);
2183 : : else
2825 rhaas@postgresql.org 2184 :UBC 0 : worker_freeze_result_tape(state);
9508 tgl@sss.pgh.pa.us 2185 :CBC 10 : state->status = TSS_SORTEDONTAPE;
2186 : :
2187 : : /* Close all the now-empty input tapes, to release their read buffers. */
1471 heikki.linnakangas@i 2188 [ + + ]: 54 : for (tapenum = 0; tapenum < state->nInputTapes; tapenum++)
2189 : 44 : LogicalTapeClose(state->inputTapes[tapenum]);
2190 : : }
2191 : :
2192 : : /*
2193 : : * Merge one run from each input tape.
2194 : : */
2195 : : static void
9508 tgl@sss.pgh.pa.us 2196 : 79 : mergeonerun(Tuplesortstate *state)
2197 : : {
2198 : : int srcTapeIndex;
2199 : : LogicalTape *srcTape;
2200 : :
2201 : : /*
2202 : : * Start the merge by loading one tuple from each active source tape into
2203 : : * the heap.
2204 : : */
3312 heikki.linnakangas@i 2205 : 79 : beginmerge(state);
2206 : :
1153 drowley@postgresql.o 2207 [ - + ]: 79 : Assert(state->slabAllocatorUsed);
2208 : :
2209 : : /*
2210 : : * Execute merge by repeatedly extracting lowest tuple in heap, writing it
2211 : : * out, and replacing it with next tuple from same tape (if there is
2212 : : * another one).
2213 : : */
9495 tgl@sss.pgh.pa.us 2214 [ + + ]: 432795 : while (state->memtupcount > 0)
2215 : : {
2216 : : SortTuple stup;
2217 : :
2218 : : /* write the tuple to destTape */
1471 heikki.linnakangas@i 2219 : 432716 : srcTapeIndex = state->memtuples[0].srctape;
2220 : 432716 : srcTape = state->inputTapes[srcTapeIndex];
2221 : 432716 : WRITETUP(state, state->destTape, &state->memtuples[0]);
2222 : :
2223 : : /* recycle the slot of the tuple we just wrote out, for the next read */
3207 tgl@sss.pgh.pa.us 2224 [ + + ]: 432716 : if (state->memtuples[0].tuple)
2225 [ + - + - ]: 367674 : RELEASE_SLAB_SLOT(state, state->memtuples[0].tuple);
2226 : :
2227 : : /*
2228 : : * pull next tuple from the tape, and replace the written-out tuple in
2229 : : * the heap with it.
2230 : : */
3312 heikki.linnakangas@i 2231 [ + + ]: 432716 : if (mergereadnext(state, srcTape, &stup))
2232 : : {
1471 2233 : 432291 : stup.srctape = srcTapeIndex;
2951 rhaas@postgresql.org 2234 : 432291 : tuplesort_heap_replace_top(state, &stup);
2235 : : }
2236 : : else
2237 : : {
2238 : 425 : tuplesort_heap_delete_top(state);
1471 heikki.linnakangas@i 2239 : 425 : state->nInputRuns--;
2240 : : }
2241 : : }
2242 : :
2243 : : /*
2244 : : * When the heap empties, we're done. Write an end-of-run marker on the
2245 : : * output tape.
2246 : : */
2247 : 79 : markrunend(state->destTape);
9508 tgl@sss.pgh.pa.us 2248 : 79 : }
2249 : :
2250 : : /*
2251 : : * beginmerge - initialize for a merge pass
2252 : : *
2253 : : * Fill the merge heap with the first tuple from each input tape.
2254 : : */
2255 : : static void
3312 heikki.linnakangas@i 2256 : 216 : beginmerge(Tuplesortstate *state)
2257 : : {
2258 : : int activeTapes;
2259 : : int srcTapeIndex;
2260 : :
2261 : : /* Heap should be empty here */
9495 tgl@sss.pgh.pa.us 2262 [ - + ]: 216 : Assert(state->memtupcount == 0);
2263 : :
1471 heikki.linnakangas@i 2264 : 216 : activeTapes = Min(state->nInputTapes, state->nInputRuns);
2265 : :
2266 [ + + ]: 983 : for (srcTapeIndex = 0; srcTapeIndex < activeTapes; srcTapeIndex++)
2267 : : {
2268 : : SortTuple tup;
2269 : :
2270 [ + + ]: 767 : if (mergereadnext(state, state->inputTapes[srcTapeIndex], &tup))
2271 : : {
2272 : 646 : tup.srctape = srcTapeIndex;
2951 rhaas@postgresql.org 2273 : 646 : tuplesort_heap_insert(state, &tup);
2274 : : }
2275 : : }
3512 2276 : 216 : }
2277 : :
2278 : : /*
2279 : : * mergereadnext - read next tuple from one merge input tape
2280 : : *
2281 : : * Returns false on EOF.
2282 : : */
2283 : : static bool
1471 heikki.linnakangas@i 2284 : 2755675 : mergereadnext(Tuplesortstate *state, LogicalTape *srcTape, SortTuple *stup)
2285 : : {
2286 : : unsigned int tuplen;
2287 : :
2288 : : /* read next tuple, if any */
2289 [ + + ]: 2755675 : if ((tuplen = getlen(srcTape, true)) == 0)
3312 2290 : 743 : return false;
2291 : 2754932 : READTUP(state, stup, srcTape, tuplen);
2292 : :
2293 : 2754932 : return true;
2294 : : }
2295 : :
2296 : : /*
2297 : : * dumptuples - remove tuples from memtuples and write initial run to tape
2298 : : *
2299 : : * When alltuples = true, dump everything currently in memory. (This case is
2300 : : * only used at end of input data.)
2301 : : */
2302 : : static void
9508 tgl@sss.pgh.pa.us 2303 : 554296 : dumptuples(Tuplesortstate *state, bool alltuples)
2304 : : {
2305 : : int memtupwrite;
2306 : : int i;
2307 : :
2308 : : /*
2309 : : * Nothing to do if we still fit in available memory and have array slots,
2310 : : * unless this is the final call during initial run generation.
2311 : : */
2951 rhaas@postgresql.org 2312 [ + + + + : 554296 : if (state->memtupcount < state->memtupsize && !LACKMEM(state) &&
- + ]
2313 [ + + ]: 553825 : !alltuples)
2314 : 553534 : return;
2315 : :
2316 : : /*
2317 : : * Final call might require no sorting, in rare cases where we just so
2318 : : * happen to have previously LACKMEM()'d at the point where exactly all
2319 : : * remaining tuples are loaded into memory, just before input was
2320 : : * exhausted. In general, short final runs are quite possible, but avoid
2321 : : * creating a completely empty run. In a worker, though, we must produce
2322 : : * at least one tape, even if it's empty.
2323 : : */
1471 heikki.linnakangas@i 2324 [ + + - + ]: 762 : if (state->memtupcount == 0 && state->currentRun > 0)
1471 heikki.linnakangas@i 2325 :UBC 0 : return;
2326 : :
3490 rhaas@postgresql.org 2327 [ - + ]:CBC 762 : Assert(state->status == TSS_BUILDRUNS);
2328 : :
2329 : : /*
2330 : : * It seems unlikely that this limit will ever be exceeded, but take no
2331 : : * chances
2332 : : */
2333 [ - + ]: 762 : if (state->currentRun == INT_MAX)
3490 rhaas@postgresql.org 2334 [ # # ]:UBC 0 : ereport(ERROR,
2335 : : (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
2336 : : errmsg("cannot have more than %d runs for an external sort",
2337 : : INT_MAX)));
2338 : :
1471 heikki.linnakangas@i 2339 [ + + ]:CBC 762 : if (state->currentRun > 0)
2340 : 471 : selectnewtape(state);
2341 : :
3490 rhaas@postgresql.org 2342 : 762 : state->currentRun++;
2343 : :
2344 [ - + ]: 762 : if (trace_sort)
2553 pg@bowt.ie 2345 [ # # ]:UBC 0 : elog(LOG, "worker %d starting quicksort of run %d: %s",
2346 : : state->worker, state->currentRun,
2347 : : pg_rusage_show(&state->ru_start));
2348 : :
2349 : : /*
2350 : : * Sort all tuples accumulated within the allowed amount of memory for
2351 : : * this run using quicksort
2352 : : */
3490 rhaas@postgresql.org 2353 :CBC 762 : tuplesort_sort_memtuples(state);
2354 : :
2355 [ - + ]: 762 : if (trace_sort)
2553 pg@bowt.ie 2356 [ # # ]:UBC 0 : elog(LOG, "worker %d finished quicksort of run %d: %s",
2357 : : state->worker, state->currentRun,
2358 : : pg_rusage_show(&state->ru_start));
2359 : :
3490 rhaas@postgresql.org 2360 :CBC 762 : memtupwrite = state->memtupcount;
2361 [ + + ]: 2575580 : for (i = 0; i < memtupwrite; i++)
2362 : : {
1153 drowley@postgresql.o 2363 : 2574818 : SortTuple *stup = &state->memtuples[i];
2364 : :
2365 : 2574818 : WRITETUP(state, state->destTape, stup);
2366 : : }
2367 : :
2368 : 762 : state->memtupcount = 0;
2369 : :
2370 : : /*
2371 : : * Reset tuple memory. We've freed all of the tuples that we previously
2372 : : * allocated. It's important to avoid fragmentation when there is a stark
2373 : : * change in the sizes of incoming tuples. In bounded sorts,
2374 : : * fragmentation due to AllocSetFree's bucketing by size class might be
2375 : : * particularly bad if this step wasn't taken.
2376 : : */
1189 akorotkov@postgresql 2377 : 762 : MemoryContextReset(state->base.tuplecontext);
2378 : :
2379 : : /*
2380 : : * Now update the memory accounting to subtract the memory used by the
2381 : : * tuple.
2382 : : */
568 drowley@postgresql.o 2383 : 762 : FREEMEM(state, state->tupleMem);
2384 : 762 : state->tupleMem = 0;
2385 : :
1471 heikki.linnakangas@i 2386 : 762 : markrunend(state->destTape);
2387 : :
3490 rhaas@postgresql.org 2388 [ - + ]: 762 : if (trace_sort)
2553 pg@bowt.ie 2389 [ # # ]:UBC 0 : elog(LOG, "worker %d finished writing run %d to tape %d: %s",
2390 : : state->worker, state->currentRun, (state->currentRun - 1) % state->nOutputTapes + 1,
2391 : : pg_rusage_show(&state->ru_start));
2392 : : }
2393 : :
2394 : : /*
2395 : : * tuplesort_rescan - rewind and replay the scan
2396 : : */
2397 : : void
9508 tgl@sss.pgh.pa.us 2398 :CBC 23 : tuplesort_rescan(Tuplesortstate *state)
2399 : : {
1189 akorotkov@postgresql 2400 : 23 : MemoryContext oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
2401 : :
2402 [ - + ]: 23 : Assert(state->base.sortopt & TUPLESORT_RANDOMACCESS);
2403 : :
9508 tgl@sss.pgh.pa.us 2404 [ + + - ]: 23 : switch (state->status)
2405 : : {
2406 : 20 : case TSS_SORTEDINMEM:
2407 : 20 : state->current = 0;
2408 : 20 : state->eof_reached = false;
2409 : 20 : state->markpos_offset = 0;
2410 : 20 : state->markpos_eof = false;
2411 : 20 : break;
2412 : 3 : case TSS_SORTEDONTAPE:
1471 heikki.linnakangas@i 2413 : 3 : LogicalTapeRewindForRead(state->result_tape, 0);
9508 tgl@sss.pgh.pa.us 2414 : 3 : state->eof_reached = false;
2415 : 3 : state->markpos_block = 0L;
2416 : 3 : state->markpos_offset = 0;
2417 : 3 : state->markpos_eof = false;
2418 : 3 : break;
9508 tgl@sss.pgh.pa.us 2419 :UBC 0 : default:
8131 2420 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
2421 : : break;
2422 : : }
2423 : :
7184 tgl@sss.pgh.pa.us 2424 :CBC 23 : MemoryContextSwitchTo(oldcontext);
9508 2425 : 23 : }
2426 : :
2427 : : /*
2428 : : * tuplesort_markpos - saves current position in the merged sort file
2429 : : */
2430 : : void
2431 : 294471 : tuplesort_markpos(Tuplesortstate *state)
2432 : : {
1189 akorotkov@postgresql 2433 : 294471 : MemoryContext oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
2434 : :
2435 [ - + ]: 294471 : Assert(state->base.sortopt & TUPLESORT_RANDOMACCESS);
2436 : :
9508 tgl@sss.pgh.pa.us 2437 [ + + - ]: 294471 : switch (state->status)
2438 : : {
2439 : 290067 : case TSS_SORTEDINMEM:
2440 : 290067 : state->markpos_offset = state->current;
2441 : 290067 : state->markpos_eof = state->eof_reached;
2442 : 290067 : break;
2443 : 4404 : case TSS_SORTEDONTAPE:
1471 heikki.linnakangas@i 2444 : 4404 : LogicalTapeTell(state->result_tape,
2445 : : &state->markpos_block,
2446 : : &state->markpos_offset);
9508 tgl@sss.pgh.pa.us 2447 : 4404 : state->markpos_eof = state->eof_reached;
2448 : 4404 : break;
9508 tgl@sss.pgh.pa.us 2449 :UBC 0 : default:
8131 2450 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
2451 : : break;
2452 : : }
2453 : :
7184 tgl@sss.pgh.pa.us 2454 :CBC 294471 : MemoryContextSwitchTo(oldcontext);
9508 2455 : 294471 : }
2456 : :
2457 : : /*
2458 : : * tuplesort_restorepos - restores current position in merged sort file to
2459 : : * last saved position
2460 : : */
2461 : : void
2462 : 19354 : tuplesort_restorepos(Tuplesortstate *state)
2463 : : {
1189 akorotkov@postgresql 2464 : 19354 : MemoryContext oldcontext = MemoryContextSwitchTo(state->base.sortcontext);
2465 : :
2466 [ - + ]: 19354 : Assert(state->base.sortopt & TUPLESORT_RANDOMACCESS);
2467 : :
9508 tgl@sss.pgh.pa.us 2468 [ + + - ]: 19354 : switch (state->status)
2469 : : {
2470 : 16258 : case TSS_SORTEDINMEM:
2471 : 16258 : state->current = state->markpos_offset;
2472 : 16258 : state->eof_reached = state->markpos_eof;
2473 : 16258 : break;
2474 : 3096 : case TSS_SORTEDONTAPE:
1471 heikki.linnakangas@i 2475 : 3096 : LogicalTapeSeek(state->result_tape,
2476 : : state->markpos_block,
2477 : : state->markpos_offset);
9508 tgl@sss.pgh.pa.us 2478 : 3096 : state->eof_reached = state->markpos_eof;
2479 : 3096 : break;
9508 tgl@sss.pgh.pa.us 2480 :UBC 0 : default:
8131 2481 [ # # ]: 0 : elog(ERROR, "invalid tuplesort state");
2482 : : break;
2483 : : }
2484 : :
7184 tgl@sss.pgh.pa.us 2485 :CBC 19354 : MemoryContextSwitchTo(oldcontext);
9508 2486 : 19354 : }
2487 : :
2488 : : /*
2489 : : * tuplesort_get_stats - extract summary statistics
2490 : : *
2491 : : * This can be called after tuplesort_performsort() finishes to obtain
2492 : : * printable summary information about how the sort was performed.
2493 : : */
2494 : : void
5923 2495 : 198 : tuplesort_get_stats(Tuplesortstate *state,
2496 : : TuplesortInstrumentation *stats)
2497 : : {
2498 : : /*
2499 : : * Note: it might seem we should provide both memory and disk usage for a
2500 : : * disk-based sort. However, the current code doesn't track memory space
2501 : : * accurately once we have begun to return tuples to the caller (since we
2502 : : * don't account for pfree's the caller is expected to do), so we cannot
2503 : : * rely on availMem in a disk sort. This does not seem worth the overhead
2504 : : * to fix. Is it worth creating an API for the memory context code to
2505 : : * tell us how much is actually used in sortcontext?
2506 : : */
2031 tomas.vondra@postgre 2507 : 198 : tuplesort_updatemax(state);
2508 : :
2509 [ + + ]: 198 : if (state->isMaxSpaceDisk)
2982 rhaas@postgresql.org 2510 : 3 : stats->spaceType = SORT_SPACE_TYPE_DISK;
2511 : : else
2512 : 195 : stats->spaceType = SORT_SPACE_TYPE_MEMORY;
2031 tomas.vondra@postgre 2513 : 198 : stats->spaceUsed = (state->maxSpace + 1023) / 1024;
2514 : :
2515 [ + - + - ]: 198 : switch (state->maxSpaceStatus)
2516 : : {
6752 tgl@sss.pgh.pa.us 2517 : 195 : case TSS_SORTEDINMEM:
2518 [ + + ]: 195 : if (state->boundUsed)
2982 rhaas@postgresql.org 2519 : 21 : stats->sortMethod = SORT_TYPE_TOP_N_HEAPSORT;
2520 : : else
2521 : 174 : stats->sortMethod = SORT_TYPE_QUICKSORT;
6752 tgl@sss.pgh.pa.us 2522 : 195 : break;
6752 tgl@sss.pgh.pa.us 2523 :UBC 0 : case TSS_SORTEDONTAPE:
2982 rhaas@postgresql.org 2524 : 0 : stats->sortMethod = SORT_TYPE_EXTERNAL_SORT;
6752 tgl@sss.pgh.pa.us 2525 : 0 : break;
6752 tgl@sss.pgh.pa.us 2526 :CBC 3 : case TSS_FINALMERGE:
2982 rhaas@postgresql.org 2527 : 3 : stats->sortMethod = SORT_TYPE_EXTERNAL_MERGE;
6752 tgl@sss.pgh.pa.us 2528 : 3 : break;
6752 tgl@sss.pgh.pa.us 2529 :UBC 0 : default:
2982 rhaas@postgresql.org 2530 : 0 : stats->sortMethod = SORT_TYPE_STILL_IN_PROGRESS;
6752 tgl@sss.pgh.pa.us 2531 : 0 : break;
2532 : : }
6752 tgl@sss.pgh.pa.us 2533 :CBC 198 : }
2534 : :
2535 : : /*
2536 : : * Convert TuplesortMethod to a string.
2537 : : */
2538 : : const char *
2982 rhaas@postgresql.org 2539 : 147 : tuplesort_method_name(TuplesortMethod m)
2540 : : {
2541 [ - + + - : 147 : switch (m)
+ - ]
2542 : : {
2982 rhaas@postgresql.org 2543 :UBC 0 : case SORT_TYPE_STILL_IN_PROGRESS:
2544 : 0 : return "still in progress";
2982 rhaas@postgresql.org 2545 :CBC 21 : case SORT_TYPE_TOP_N_HEAPSORT:
2546 : 21 : return "top-N heapsort";
2547 : 123 : case SORT_TYPE_QUICKSORT:
2548 : 123 : return "quicksort";
2982 rhaas@postgresql.org 2549 :UBC 0 : case SORT_TYPE_EXTERNAL_SORT:
2550 : 0 : return "external sort";
2982 rhaas@postgresql.org 2551 :CBC 3 : case SORT_TYPE_EXTERNAL_MERGE:
2552 : 3 : return "external merge";
2553 : : }
2554 : :
2982 rhaas@postgresql.org 2555 :UBC 0 : return "unknown";
2556 : : }
2557 : :
2558 : : /*
2559 : : * Convert TuplesortSpaceType to a string.
2560 : : */
2561 : : const char *
2982 rhaas@postgresql.org 2562 :CBC 129 : tuplesort_space_type_name(TuplesortSpaceType t)
2563 : : {
2564 [ + + - + ]: 129 : Assert(t == SORT_SPACE_TYPE_DISK || t == SORT_SPACE_TYPE_MEMORY);
2565 [ + + ]: 129 : return t == SORT_SPACE_TYPE_DISK ? "Disk" : "Memory";
2566 : : }
2567 : :
2568 : :
2569 : : /*
2570 : : * Heap manipulation routines, per Knuth's Algorithm 5.2.3H.
2571 : : */
2572 : :
2573 : : /*
2574 : : * Convert the existing unordered array of SortTuples to a bounded heap,
2575 : : * discarding all but the smallest "state->bound" tuples.
2576 : : *
2577 : : * When working with a bounded heap, we want to keep the largest entry
2578 : : * at the root (array entry zero), instead of the smallest as in the normal
2579 : : * sort case. This allows us to discard the largest entry cheaply.
2580 : : * Therefore, we temporarily reverse the sort direction.
2581 : : */
2582 : : static void
6752 tgl@sss.pgh.pa.us 2583 : 210 : make_bounded_heap(Tuplesortstate *state)
2584 : : {
6557 bruce@momjian.us 2585 : 210 : int tupcount = state->memtupcount;
2586 : : int i;
2587 : :
6752 tgl@sss.pgh.pa.us 2588 [ - + ]: 210 : Assert(state->status == TSS_INITIAL);
2589 [ - + ]: 210 : Assert(state->bounded);
2590 [ - + ]: 210 : Assert(tupcount >= state->bound);
2825 rhaas@postgresql.org 2591 [ - + ]: 210 : Assert(SERIAL(state));
2592 : :
2593 : : /* Reverse sort direction so largest entry will be at root */
4008 2594 : 210 : reversedirection(state);
2595 : :
6752 tgl@sss.pgh.pa.us 2596 : 210 : state->memtupcount = 0; /* make the heap empty */
6557 bruce@momjian.us 2597 [ + + ]: 23046 : for (i = 0; i < tupcount; i++)
2598 : : {
3334 heikki.linnakangas@i 2599 [ + + ]: 22836 : if (state->memtupcount < state->bound)
2600 : : {
2601 : : /* Insert next tuple into heap */
2602 : : /* Must copy source tuple to avoid possible overwrite */
6557 bruce@momjian.us 2603 : 11313 : SortTuple stup = state->memtuples[i];
2604 : :
2951 rhaas@postgresql.org 2605 : 11313 : tuplesort_heap_insert(state, &stup);
2606 : : }
2607 : : else
2608 : : {
2609 : : /*
2610 : : * The heap is full. Replace the largest entry with the new
2611 : : * tuple, or just discard it, if it's larger than anything already
2612 : : * in the heap.
2613 : : */
3334 heikki.linnakangas@i 2614 [ + + ]: 11523 : if (COMPARETUP(state, &state->memtuples[i], &state->memtuples[0]) <= 0)
2615 : : {
2616 : 5546 : free_sort_tuple(state, &state->memtuples[i]);
2617 [ - + ]: 5546 : CHECK_FOR_INTERRUPTS();
2618 : : }
2619 : : else
2951 rhaas@postgresql.org 2620 : 5977 : tuplesort_heap_replace_top(state, &state->memtuples[i]);
2621 : : }
2622 : : }
2623 : :
6752 tgl@sss.pgh.pa.us 2624 [ - + ]: 210 : Assert(state->memtupcount == state->bound);
2625 : 210 : state->status = TSS_BOUNDED;
2626 : 210 : }
2627 : :
2628 : : /*
2629 : : * Convert the bounded heap to a properly-sorted array
2630 : : */
2631 : : static void
2632 : 210 : sort_bounded_heap(Tuplesortstate *state)
2633 : : {
6557 bruce@momjian.us 2634 : 210 : int tupcount = state->memtupcount;
2635 : :
6752 tgl@sss.pgh.pa.us 2636 [ - + ]: 210 : Assert(state->status == TSS_BOUNDED);
2637 [ - + ]: 210 : Assert(state->bounded);
2638 [ - + ]: 210 : Assert(tupcount == state->bound);
2825 rhaas@postgresql.org 2639 [ - + ]: 210 : Assert(SERIAL(state));
2640 : :
2641 : : /*
2642 : : * We can unheapify in place because each delete-top call will remove the
2643 : : * largest entry, which we can promptly store in the newly freed slot at
2644 : : * the end. Once we're down to a single-entry heap, we're done.
2645 : : */
6752 tgl@sss.pgh.pa.us 2646 [ + + ]: 11313 : while (state->memtupcount > 1)
2647 : : {
6557 bruce@momjian.us 2648 : 11103 : SortTuple stup = state->memtuples[0];
2649 : :
2650 : : /* this sifts-up the next-largest entry and decreases memtupcount */
2951 rhaas@postgresql.org 2651 : 11103 : tuplesort_heap_delete_top(state);
6752 tgl@sss.pgh.pa.us 2652 : 11103 : state->memtuples[state->memtupcount] = stup;
2653 : : }
2654 : 210 : state->memtupcount = tupcount;
2655 : :
2656 : : /*
2657 : : * Reverse sort direction back to the original state. This is not
2658 : : * actually necessary but seems like a good idea for tidiness.
2659 : : */
4008 rhaas@postgresql.org 2660 : 210 : reversedirection(state);
2661 : :
6752 tgl@sss.pgh.pa.us 2662 : 210 : state->status = TSS_SORTEDINMEM;
2663 : 210 : state->boundUsed = true;
2664 : 210 : }
2665 : :
2666 : : /*
2667 : : * Sort all memtuples using specialized qsort() routines.
2668 : : *
2669 : : * Quicksort is used for small in-memory sorts, and external sort runs.
2670 : : */
2671 : : static void
3490 rhaas@postgresql.org 2672 : 117650 : tuplesort_sort_memtuples(Tuplesortstate *state)
2673 : : {
2825 2674 [ + + - + ]: 117650 : Assert(!LEADER(state));
2675 : :
3490 2676 [ + + ]: 117650 : if (state->memtupcount > 1)
2677 : : {
2678 : : /*
2679 : : * Do we have the leading column's value or abbreviation in datum1,
2680 : : * and is there a specialization for its comparator?
2681 : : */
1189 akorotkov@postgresql 2682 [ + + + + ]: 33992 : if (state->base.haveDatum1 && state->base.sortKeys)
2683 : : {
2684 [ + + ]: 33972 : if (state->base.sortKeys[0].comparator == ssup_datum_unsigned_cmp)
2685 : : {
1303 tmunro@postgresql.or 2686 : 1672 : qsort_tuple_unsigned(state->memtuples,
2687 : 1672 : state->memtupcount,
2688 : : state);
2689 : 1664 : return;
2690 : : }
1189 akorotkov@postgresql 2691 [ + + ]: 32300 : else if (state->base.sortKeys[0].comparator == ssup_datum_signed_cmp)
2692 : : {
1303 tmunro@postgresql.or 2693 : 708 : qsort_tuple_signed(state->memtuples,
2694 : 708 : state->memtupcount,
2695 : : state);
2696 : 708 : return;
2697 : : }
1189 akorotkov@postgresql 2698 [ + + ]: 31592 : else if (state->base.sortKeys[0].comparator == ssup_datum_int32_cmp)
2699 : : {
1303 tmunro@postgresql.or 2700 : 19937 : qsort_tuple_int32(state->memtuples,
2701 : 19937 : state->memtupcount,
2702 : : state);
2703 : 19907 : return;
2704 : : }
2705 : : }
2706 : :
2707 : : /* Can we use the single-key sort function? */
1189 akorotkov@postgresql 2708 [ + + ]: 11675 : if (state->base.onlyKey != NULL)
2709 : : {
3490 rhaas@postgresql.org 2710 : 5034 : qsort_ssup(state->memtuples, state->memtupcount,
1189 akorotkov@postgresql 2711 : 5034 : state->base.onlyKey);
2712 : : }
2713 : : else
2714 : : {
3490 rhaas@postgresql.org 2715 : 6641 : qsort_tuple(state->memtuples,
2716 : 6641 : state->memtupcount,
2717 : : state->base.comparetup,
2718 : : state);
2719 : : }
2720 : : }
2721 : : }
2722 : :
2723 : : /*
2724 : : * Insert a new tuple into an empty or existing heap, maintaining the
2725 : : * heap invariant. Caller is responsible for ensuring there's room.
2726 : : *
2727 : : * Note: For some callers, tuple points to a memtuples[] entry above the
2728 : : * end of the heap. This is safe as long as it's not immediately adjacent
2729 : : * to the end of the heap (ie, in the [memtupcount] array entry) --- if it
2730 : : * is, it might get overwritten before being moved into the heap!
2731 : : */
2732 : : static void
2951 2733 : 11959 : tuplesort_heap_insert(Tuplesortstate *state, SortTuple *tuple)
2734 : : {
2735 : : SortTuple *memtuples;
2736 : : int j;
2737 : :
9495 tgl@sss.pgh.pa.us 2738 : 11959 : memtuples = state->memtuples;
7184 2739 [ - + ]: 11959 : Assert(state->memtupcount < state->memtupsize);
2740 : :
4970 rhaas@postgresql.org 2741 [ + + ]: 11959 : CHECK_FOR_INTERRUPTS();
2742 : :
2743 : : /*
2744 : : * Sift-up the new entry, per Knuth 5.2.3 exercise 16. Note that Knuth is
2745 : : * using 1-based array indexes, not 0-based.
2746 : : */
9495 tgl@sss.pgh.pa.us 2747 : 11959 : j = state->memtupcount++;
2748 [ + + ]: 33303 : while (j > 0)
2749 : : {
9330 bruce@momjian.us 2750 : 29883 : int i = (j - 1) >> 1;
2751 : :
2951 rhaas@postgresql.org 2752 [ + + ]: 29883 : if (COMPARETUP(state, tuple, &memtuples[i]) >= 0)
9508 tgl@sss.pgh.pa.us 2753 : 8539 : break;
9495 2754 : 21344 : memtuples[j] = memtuples[i];
9508 2755 : 21344 : j = i;
2756 : : }
7184 2757 : 11959 : memtuples[j] = *tuple;
9508 2758 : 11959 : }
2759 : :
2760 : : /*
2761 : : * Remove the tuple at state->memtuples[0] from the heap. Decrement
2762 : : * memtupcount, and sift up to maintain the heap invariant.
2763 : : *
2764 : : * The caller has already free'd the tuple the top node points to,
2765 : : * if necessary.
2766 : : */
2767 : : static void
2951 rhaas@postgresql.org 2768 : 11725 : tuplesort_heap_delete_top(Tuplesortstate *state)
2769 : : {
7184 tgl@sss.pgh.pa.us 2770 : 11725 : SortTuple *memtuples = state->memtuples;
2771 : : SortTuple *tuple;
2772 : :
9495 2773 [ + + ]: 11725 : if (--state->memtupcount <= 0)
9508 2774 : 150 : return;
2775 : :
2776 : : /*
2777 : : * Remove the last tuple in the heap, and re-insert it, by replacing the
2778 : : * current top node with it.
2779 : : */
3334 heikki.linnakangas@i 2780 : 11575 : tuple = &memtuples[state->memtupcount];
2951 rhaas@postgresql.org 2781 : 11575 : tuplesort_heap_replace_top(state, tuple);
2782 : : }
2783 : :
2784 : : /*
2785 : : * Replace the tuple at state->memtuples[0] with a new tuple. Sift up to
2786 : : * maintain the heap invariant.
2787 : : *
2788 : : * This corresponds to Knuth's "sift-up" algorithm (Algorithm 5.2.3H,
2789 : : * Heapsort, steps H3-H8).
2790 : : */
2791 : : static void
2792 : 3023101 : tuplesort_heap_replace_top(Tuplesortstate *state, SortTuple *tuple)
2793 : : {
3334 heikki.linnakangas@i 2794 : 3023101 : SortTuple *memtuples = state->memtuples;
2795 : : unsigned int i,
2796 : : n;
2797 : :
2798 [ - + ]: 3023101 : Assert(state->memtupcount >= 1);
2799 : :
4970 rhaas@postgresql.org 2800 [ - + ]: 3023101 : CHECK_FOR_INTERRUPTS();
2801 : :
2802 : : /*
2803 : : * state->memtupcount is "int", but we use "unsigned int" for i, j, n.
2804 : : * This prevents overflow in the "2 * i + 1" calculation, since at the top
2805 : : * of the loop we must have i < n <= INT_MAX <= UINT_MAX/2.
2806 : : */
9495 tgl@sss.pgh.pa.us 2807 : 3023101 : n = state->memtupcount;
9508 2808 : 3023101 : i = 0; /* i is where the "hole" is */
2809 : : for (;;)
9495 2810 : 941325 : {
3030 2811 : 3964426 : unsigned int j = 2 * i + 1;
2812 : :
9508 2813 [ + + ]: 3964426 : if (j >= n)
2814 : 607898 : break;
9330 bruce@momjian.us 2815 [ + + + + ]: 4600559 : if (j + 1 < n &&
2951 rhaas@postgresql.org 2816 : 1244031 : COMPARETUP(state, &memtuples[j], &memtuples[j + 1]) > 0)
9508 tgl@sss.pgh.pa.us 2817 : 498285 : j++;
2951 rhaas@postgresql.org 2818 [ + + ]: 3356528 : if (COMPARETUP(state, tuple, &memtuples[j]) <= 0)
9508 tgl@sss.pgh.pa.us 2819 : 2415203 : break;
9495 2820 : 941325 : memtuples[i] = memtuples[j];
9508 2821 : 941325 : i = j;
2822 : : }
7184 2823 : 3023101 : memtuples[i] = *tuple;
9508 2824 : 3023101 : }
2825 : :
2826 : : /*
2827 : : * Function to reverse the sort direction from its current state
2828 : : *
2829 : : * It is not safe to call this when performing hash tuplesorts
2830 : : */
2831 : : static void
4008 rhaas@postgresql.org 2832 : 420 : reversedirection(Tuplesortstate *state)
2833 : : {
1189 akorotkov@postgresql 2834 : 420 : SortSupport sortKey = state->base.sortKeys;
2835 : : int nkey;
2836 : :
2837 [ + + ]: 1020 : for (nkey = 0; nkey < state->base.nKeys; nkey++, sortKey++)
2838 : : {
4008 rhaas@postgresql.org 2839 : 600 : sortKey->ssup_reverse = !sortKey->ssup_reverse;
2840 : 600 : sortKey->ssup_nulls_first = !sortKey->ssup_nulls_first;
2841 : : }
2842 : 420 : }
2843 : :
2844 : :
2845 : : /*
2846 : : * Tape interface routines
2847 : : */
2848 : :
2849 : : static unsigned int
1471 heikki.linnakangas@i 2850 : 2897179 : getlen(LogicalTape *tape, bool eofOK)
2851 : : {
2852 : : unsigned int len;
2853 : :
2854 [ - + ]: 2897179 : if (LogicalTapeRead(tape,
2855 : : &len, sizeof(len)) != sizeof(len))
8131 tgl@sss.pgh.pa.us 2856 [ # # ]:UBC 0 : elog(ERROR, "unexpected end of tape");
9508 tgl@sss.pgh.pa.us 2857 [ + + - + ]:CBC 2897179 : if (len == 0 && !eofOK)
8131 tgl@sss.pgh.pa.us 2858 [ # # ]:UBC 0 : elog(ERROR, "unexpected end of data");
9508 tgl@sss.pgh.pa.us 2859 :CBC 2897179 : return len;
2860 : : }
2861 : :
2862 : : static void
1471 heikki.linnakangas@i 2863 : 841 : markrunend(LogicalTape *tape)
2864 : : {
9330 bruce@momjian.us 2865 : 841 : unsigned int len = 0;
2866 : :
1033 peter@eisentraut.org 2867 : 841 : LogicalTapeWrite(tape, &len, sizeof(len));
9508 tgl@sss.pgh.pa.us 2868 : 841 : }
2869 : :
2870 : : /*
2871 : : * Get memory for tuple from within READTUP() routine.
2872 : : *
2873 : : * We use next free slot from the slab allocator, or palloc() if the tuple
2874 : : * is too large for that.
2875 : : */
2876 : : void *
1189 akorotkov@postgresql 2877 : 2706300 : tuplesort_readtup_alloc(Tuplesortstate *state, Size tuplen)
2878 : : {
2879 : : SlabSlot *buf;
2880 : :
2881 : : /*
2882 : : * We pre-allocate enough slots in the slab arena that we should never run
2883 : : * out.
2884 : : */
3312 heikki.linnakangas@i 2885 [ - + ]: 2706300 : Assert(state->slabFreeHead);
2886 : :
2887 [ + - - + ]: 2706300 : if (tuplen > SLAB_SLOT_SIZE || !state->slabFreeHead)
1189 akorotkov@postgresql 2888 :UBC 0 : return MemoryContextAlloc(state->base.sortcontext, tuplen);
2889 : : else
2890 : : {
3312 heikki.linnakangas@i 2891 :CBC 2706300 : buf = state->slabFreeHead;
2892 : : /* Reuse this slot */
2893 : 2706300 : state->slabFreeHead = buf->nextfree;
2894 : :
2895 : 2706300 : return buf;
2896 : : }
2897 : : }
2898 : :
2899 : :
2900 : : /*
2901 : : * Parallel sort routines
2902 : : */
2903 : :
2904 : : /*
2905 : : * tuplesort_estimate_shared - estimate required shared memory allocation
2906 : : *
2907 : : * nWorkers is an estimate of the number of workers (it's the number that
2908 : : * will be requested).
2909 : : */
2910 : : Size
2825 rhaas@postgresql.org 2911 : 79 : tuplesort_estimate_shared(int nWorkers)
2912 : : {
2913 : : Size tapesSize;
2914 : :
2915 [ - + ]: 79 : Assert(nWorkers > 0);
2916 : :
2917 : : /* Make sure that BufFile shared state is MAXALIGN'd */
2918 : 79 : tapesSize = mul_size(sizeof(TapeShare), nWorkers);
2919 : 79 : tapesSize = MAXALIGN(add_size(tapesSize, offsetof(Sharedsort, tapes)));
2920 : :
2921 : 79 : return tapesSize;
2922 : : }
2923 : :
2924 : : /*
2925 : : * tuplesort_initialize_shared - initialize shared tuplesort state
2926 : : *
2927 : : * Must be called from leader process before workers are launched, to
2928 : : * establish state needed up-front for worker tuplesortstates. nWorkers
2929 : : * should match the argument passed to tuplesort_estimate_shared().
2930 : : */
2931 : : void
2932 : 111 : tuplesort_initialize_shared(Sharedsort *shared, int nWorkers, dsm_segment *seg)
2933 : : {
2934 : : int i;
2935 : :
2936 [ - + ]: 111 : Assert(nWorkers > 0);
2937 : :
2938 : 111 : SpinLockInit(&shared->mutex);
2939 : 111 : shared->currentWorker = 0;
2940 : 111 : shared->workersFinished = 0;
2941 : 111 : SharedFileSetInit(&shared->fileset, seg);
2942 : 111 : shared->nTapes = nWorkers;
2943 [ + + ]: 337 : for (i = 0; i < nWorkers; i++)
2944 : : {
2945 : 226 : shared->tapes[i].firstblocknumber = 0L;
2946 : : }
2947 : 111 : }
2948 : :
2949 : : /*
2950 : : * tuplesort_attach_shared - attach to shared tuplesort state
2951 : : *
2952 : : * Must be called by all worker processes.
2953 : : */
2954 : : void
2955 : 112 : tuplesort_attach_shared(Sharedsort *shared, dsm_segment *seg)
2956 : : {
2957 : : /* Attach to SharedFileSet */
2958 : 112 : SharedFileSetAttach(&shared->fileset, seg);
2959 : 112 : }
2960 : :
2961 : : /*
2962 : : * worker_get_identifier - Assign and return ordinal identifier for worker
2963 : : *
2964 : : * The order in which these are assigned is not well defined, and should not
2965 : : * matter; worker numbers across parallel sort participants need only be
2966 : : * distinct and gapless. logtape.c requires this.
2967 : : *
2968 : : * Note that the identifiers assigned from here have no relation to
2969 : : * ParallelWorkerNumber number, to avoid making any assumption about
2970 : : * caller's requirements. However, we do follow the ParallelWorkerNumber
2971 : : * convention of representing a non-worker with worker number -1. This
2972 : : * includes the leader, as well as serial Tuplesort processes.
2973 : : */
2974 : : static int
2975 : 222 : worker_get_identifier(Tuplesortstate *state)
2976 : : {
2977 : 222 : Sharedsort *shared = state->shared;
2978 : : int worker;
2979 : :
2980 [ + - - + ]: 222 : Assert(WORKER(state));
2981 : :
2982 [ - + ]: 222 : SpinLockAcquire(&shared->mutex);
2983 : 222 : worker = shared->currentWorker++;
2984 : 222 : SpinLockRelease(&shared->mutex);
2985 : :
2986 : 222 : return worker;
2987 : : }
2988 : :
2989 : : /*
2990 : : * worker_freeze_result_tape - freeze worker's result tape for leader
2991 : : *
2992 : : * This is called by workers just after the result tape has been determined,
2993 : : * instead of calling LogicalTapeFreeze() directly. They do so because
2994 : : * workers require a few additional steps over similar serial
2995 : : * TSS_SORTEDONTAPE external sort cases, which also happen here. The extra
2996 : : * steps are around freeing now unneeded resources, and representing to
2997 : : * leader that worker's input run is available for its merge.
2998 : : *
2999 : : * There should only be one final output run for each worker, which consists
3000 : : * of all tuples that were originally input into worker.
3001 : : */
3002 : : static void
3003 : 222 : worker_freeze_result_tape(Tuplesortstate *state)
3004 : : {
3005 : 222 : Sharedsort *shared = state->shared;
3006 : : TapeShare output;
3007 : :
3008 [ + - - + ]: 222 : Assert(WORKER(state));
1471 heikki.linnakangas@i 3009 [ - + ]: 222 : Assert(state->result_tape != NULL);
2825 rhaas@postgresql.org 3010 [ - + ]: 222 : Assert(state->memtupcount == 0);
3011 : :
3012 : : /*
3013 : : * Free most remaining memory, in case caller is sensitive to our holding
3014 : : * on to it. memtuples may not be a tiny merge heap at this point.
3015 : : */
3016 : 222 : pfree(state->memtuples);
3017 : : /* Be tidy */
3018 : 222 : state->memtuples = NULL;
3019 : 222 : state->memtupsize = 0;
3020 : :
3021 : : /*
3022 : : * Parallel worker requires result tape metadata, which is to be stored in
3023 : : * shared memory for leader
3024 : : */
1471 heikki.linnakangas@i 3025 : 222 : LogicalTapeFreeze(state->result_tape, &output);
3026 : :
3027 : : /* Store properties of output tape, and update finished worker count */
2825 rhaas@postgresql.org 3028 [ - + ]: 222 : SpinLockAcquire(&shared->mutex);
3029 : 222 : shared->tapes[state->worker] = output;
3030 : 222 : shared->workersFinished++;
3031 : 222 : SpinLockRelease(&shared->mutex);
3032 : 222 : }
3033 : :
3034 : : /*
3035 : : * worker_nomergeruns - dump memtuples in worker, without merging
3036 : : *
3037 : : * This called as an alternative to mergeruns() with a worker when no
3038 : : * merging is required.
3039 : : */
3040 : : static void
3041 : 222 : worker_nomergeruns(Tuplesortstate *state)
3042 : : {
3043 [ + - - + ]: 222 : Assert(WORKER(state));
1471 heikki.linnakangas@i 3044 [ - + ]: 222 : Assert(state->result_tape == NULL);
3045 [ - + ]: 222 : Assert(state->nOutputRuns == 1);
3046 : :
3047 : 222 : state->result_tape = state->destTape;
2825 rhaas@postgresql.org 3048 : 222 : worker_freeze_result_tape(state);
3049 : 222 : }
3050 : :
3051 : : /*
3052 : : * leader_takeover_tapes - create tapeset for leader from worker tapes
3053 : : *
3054 : : * So far, leader Tuplesortstate has performed no actual sorting. By now, all
3055 : : * sorting has occurred in workers, all of which must have already returned
3056 : : * from tuplesort_performsort().
3057 : : *
3058 : : * When this returns, leader process is left in a state that is virtually
3059 : : * indistinguishable from it having generated runs as a serial external sort
3060 : : * might have.
3061 : : */
3062 : : static void
3063 : 78 : leader_takeover_tapes(Tuplesortstate *state)
3064 : : {
3065 : 78 : Sharedsort *shared = state->shared;
3066 : 78 : int nParticipants = state->nParticipants;
3067 : : int workersFinished;
3068 : : int j;
3069 : :
3070 [ + - - + ]: 78 : Assert(LEADER(state));
3071 [ - + ]: 78 : Assert(nParticipants >= 1);
3072 : :
3073 [ - + ]: 78 : SpinLockAcquire(&shared->mutex);
3074 : 78 : workersFinished = shared->workersFinished;
3075 : 78 : SpinLockRelease(&shared->mutex);
3076 : :
3077 [ - + ]: 78 : if (nParticipants != workersFinished)
2825 rhaas@postgresql.org 3078 [ # # ]:UBC 0 : elog(ERROR, "cannot take over tapes before all workers finish");
3079 : :
3080 : : /*
3081 : : * Create the tapeset from worker tapes, including a leader-owned tape at
3082 : : * the end. Parallel workers are far more expensive than logical tapes,
3083 : : * so the number of tapes allocated here should never be excessive.
3084 : : */
1471 heikki.linnakangas@i 3085 :CBC 78 : inittapestate(state, nParticipants);
3086 : 78 : state->tapeset = LogicalTapeSetCreate(false, &shared->fileset, -1);
3087 : :
3088 : : /*
3089 : : * Set currentRun to reflect the number of runs we will merge (it's not
3090 : : * used for anything, this is just pro forma)
3091 : : */
2825 rhaas@postgresql.org 3092 : 78 : state->currentRun = nParticipants;
3093 : :
3094 : : /*
3095 : : * Initialize the state to look the same as after building the initial
3096 : : * runs.
3097 : : *
3098 : : * There will always be exactly 1 run per worker, and exactly one input
3099 : : * tape per run, because workers always output exactly 1 run, even when
3100 : : * there were no input tuples for workers to sort.
3101 : : */
1471 heikki.linnakangas@i 3102 : 78 : state->inputTapes = NULL;
3103 : 78 : state->nInputTapes = 0;
3104 : 78 : state->nInputRuns = 0;
3105 : :
3106 : 78 : state->outputTapes = palloc0(nParticipants * sizeof(LogicalTape *));
3107 : 78 : state->nOutputTapes = nParticipants;
3108 : 78 : state->nOutputRuns = nParticipants;
3109 : :
3110 [ + + ]: 236 : for (j = 0; j < nParticipants; j++)
3111 : : {
3112 : 158 : state->outputTapes[j] = LogicalTapeImport(state->tapeset, j, &shared->tapes[j]);
3113 : : }
3114 : :
2825 rhaas@postgresql.org 3115 : 78 : state->status = TSS_BUILDRUNS;
3116 : 78 : }
3117 : :
3118 : : /*
3119 : : * Convenience routine to free a tuple previously loaded into sort memory
3120 : : */
3121 : : static void
6752 tgl@sss.pgh.pa.us 3122 : 1876084 : free_sort_tuple(Tuplesortstate *state, SortTuple *stup)
3123 : : {
1568 drowley@postgresql.o 3124 [ + + ]: 1876084 : if (stup->tuple)
3125 : : {
3126 : 1799848 : FREEMEM(state, GetMemoryChunkSpace(stup->tuple));
3127 : 1799848 : pfree(stup->tuple);
3128 : 1799848 : stup->tuple = NULL;
3129 : : }
6752 tgl@sss.pgh.pa.us 3130 : 1876084 : }
3131 : :
3132 : : int
1305 john.naylor@postgres 3133 :UBC 0 : ssup_datum_unsigned_cmp(Datum x, Datum y, SortSupport ssup)
3134 : : {
3135 [ # # ]: 0 : if (x < y)
3136 : 0 : return -1;
3137 [ # # ]: 0 : else if (x > y)
3138 : 0 : return 1;
3139 : : else
3140 : 0 : return 0;
3141 : : }
3142 : :
3143 : : int
1305 john.naylor@postgres 3144 :CBC 593387 : ssup_datum_signed_cmp(Datum x, Datum y, SortSupport ssup)
3145 : : {
1266 drowley@postgresql.o 3146 : 593387 : int64 xx = DatumGetInt64(x);
3147 : 593387 : int64 yy = DatumGetInt64(y);
3148 : :
1305 john.naylor@postgres 3149 [ + + ]: 593387 : if (xx < yy)
3150 : 227077 : return -1;
3151 [ + + ]: 366310 : else if (xx > yy)
3152 : 182124 : return 1;
3153 : : else
3154 : 184186 : return 0;
3155 : : }
3156 : :
3157 : : int
3158 : 97779429 : ssup_datum_int32_cmp(Datum x, Datum y, SortSupport ssup)
3159 : : {
1266 drowley@postgresql.o 3160 : 97779429 : int32 xx = DatumGetInt32(x);
3161 : 97779429 : int32 yy = DatumGetInt32(y);
3162 : :
1305 john.naylor@postgres 3163 [ + + ]: 97779429 : if (xx < yy)
3164 : 23766455 : return -1;
3165 [ + + ]: 74012974 : else if (xx > yy)
3166 : 22554745 : return 1;
3167 : : else
3168 : 51458229 : return 0;
3169 : : }
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