Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * pgpa_join.c
4 : : * analysis of joins in Plan trees
5 : : *
6 : : * Copyright (c) 2016-2026, PostgreSQL Global Development Group
7 : : *
8 : : * contrib/pg_plan_advice/pgpa_join.c
9 : : *
10 : : *-------------------------------------------------------------------------
11 : : */
12 : :
13 : : #include "postgres.h"
14 : :
15 : : #include "pgpa_join.h"
16 : : #include "pgpa_scan.h"
17 : : #include "pgpa_walker.h"
18 : :
19 : : #include "nodes/pathnodes.h"
20 : : #include "nodes/print.h"
21 : : #include "parser/parsetree.h"
22 : :
23 : : /*
24 : : * Temporary object used when unrolling a join tree.
25 : : */
26 : : struct pgpa_join_unroller
27 : : {
28 : : unsigned nallocated;
29 : : unsigned nused;
30 : : Plan *outer_subplan;
31 : : ElidedNode *outer_elided_node;
32 : : bool outer_beneath_any_gather;
33 : : pgpa_join_strategy *strategy;
34 : : Plan **inner_subplans;
35 : : ElidedNode **inner_elided_nodes;
36 : : pgpa_join_unroller **inner_unrollers;
37 : : bool *inner_beneath_any_gather;
38 : : };
39 : :
40 : : static pgpa_join_strategy pgpa_decompose_join(pgpa_plan_walker_context *walker,
41 : : Plan *plan,
42 : : Plan **realouter,
43 : : Plan **realinner,
44 : : ElidedNode **elidedrealouter,
45 : : ElidedNode **elidedrealinner,
46 : : bool *found_any_outer_gather,
47 : : bool *found_any_inner_gather);
48 : : static ElidedNode *pgpa_descend_node(PlannedStmt *pstmt, Plan **plan);
49 : : static ElidedNode *pgpa_descend_any_gather(PlannedStmt *pstmt, Plan **plan,
50 : : bool *found_any_gather);
51 : : static bool pgpa_descend_any_unique(PlannedStmt *pstmt, Plan **plan,
52 : : ElidedNode **elided_node);
53 : :
54 : : static bool is_result_node_with_child(Plan *plan);
55 : : static bool is_sorting_plan(Plan *plan);
56 : :
57 : : /*
58 : : * Create an initially-empty object for unrolling joins.
59 : : *
60 : : * This function creates a helper object that can later be used to create a
61 : : * pgpa_unrolled_join, after first calling pgpa_unroll_join one or more times.
62 : : */
63 : : pgpa_join_unroller *
54 rhaas@postgresql.org 64 :GNC 23421 : pgpa_create_join_unroller(void)
65 : : {
66 : : pgpa_join_unroller *join_unroller;
67 : :
68 : 23421 : join_unroller = palloc0_object(pgpa_join_unroller);
69 : 23421 : join_unroller->nallocated = 4;
70 : 23421 : join_unroller->strategy =
71 : 23421 : palloc_array(pgpa_join_strategy, join_unroller->nallocated);
72 : 23421 : join_unroller->inner_subplans =
73 : 23421 : palloc_array(Plan *, join_unroller->nallocated);
74 : 23421 : join_unroller->inner_elided_nodes =
75 : 23421 : palloc_array(ElidedNode *, join_unroller->nallocated);
76 : 23421 : join_unroller->inner_unrollers =
77 : 23421 : palloc_array(pgpa_join_unroller *, join_unroller->nallocated);
78 : 23421 : join_unroller->inner_beneath_any_gather =
79 : 23421 : palloc_array(bool, join_unroller->nallocated);
80 : :
81 : 23421 : return join_unroller;
82 : : }
83 : :
84 : : /*
85 : : * Unroll one level of an unrollable join tree.
86 : : *
87 : : * Our basic goal here is to unroll join trees as they occur in the Plan
88 : : * tree into a simpler and more regular structure that we can more easily
89 : : * use for further processing. Unrolling is outer-deep, so if the plan tree
90 : : * has Join1(Join2(A,B),Join3(C,D)), the same join unroller object should be
91 : : * used for Join1 and Join2, but a different one will be needed for Join3,
92 : : * since that involves a join within the *inner* side of another join.
93 : : *
94 : : * pgpa_plan_walker creates a "top level" join unroller object when it
95 : : * encounters a join in a portion of the plan tree in which no join unroller
96 : : * is already active. From there, this function is responsible for determining
97 : : * to what portion of the plan tree that join unroller applies, and for
98 : : * creating any subordinate join unroller objects that are needed as a result
99 : : * of non-outer-deep join trees. We do this by returning the join unroller
100 : : * objects that should be used for further traversal of the outer and inner
101 : : * subtrees of the current plan node via *outer_join_unroller and
102 : : * *inner_join_unroller, respectively.
103 : : */
104 : : void
105 : 30603 : pgpa_unroll_join(pgpa_plan_walker_context *walker, Plan *plan,
106 : : bool beneath_any_gather,
107 : : pgpa_join_unroller *join_unroller,
108 : : pgpa_join_unroller **outer_join_unroller,
109 : : pgpa_join_unroller **inner_join_unroller)
110 : : {
111 : : pgpa_join_strategy strategy;
112 : : Plan *realinner,
113 : : *realouter;
114 : : ElidedNode *elidedinner,
115 : : *elidedouter;
116 : : int n;
117 : 30603 : bool found_any_outer_gather = false;
118 : 30603 : bool found_any_inner_gather = false;
119 : :
120 [ - + ]: 30603 : Assert(join_unroller != NULL);
121 : :
122 : : /*
123 : : * We need to pass the join_unroller object down through certain types of
124 : : * plan nodes -- anything that's considered part of the join strategy, and
125 : : * any other nodes that can occur in a join tree despite not being scans
126 : : * or joins.
127 : : *
128 : : * This includes:
129 : : *
130 : : * (1) Materialize, Memoize, and Hash nodes, which are part of the join
131 : : * strategy,
132 : : *
133 : : * (2) Gather and Gather Merge nodes, which can occur at any point in the
134 : : * join tree where the planner decided to initiate parallelism,
135 : : *
136 : : * (3) Sort and IncrementalSort nodes, which can occur beneath MergeJoin
137 : : * or GatherMerge,
138 : : *
139 : : * (4) Agg and Unique nodes, which can occur when we decide to make the
140 : : * nullable side of a semijoin unique and then join the result, and
141 : : *
142 : : * (5) Result nodes with children, which can be added either to project to
143 : : * enforce a one-time filter (but Result nodes without children are
144 : : * degenerate scans or joins).
145 : : */
146 [ + + + - : 30603 : if (IsA(plan, Material) || IsA(plan, Memoize) || IsA(plan, Hash)
+ + ]
147 [ + + + - ]: 30002 : || IsA(plan, Gather) || IsA(plan, GatherMerge)
148 [ + + + + : 29978 : || is_sorting_plan(plan) || IsA(plan, Agg) || IsA(plan, Unique)
+ + ]
149 [ + + ]: 29761 : || is_result_node_with_child(plan))
150 : : {
151 : 844 : *outer_join_unroller = join_unroller;
152 : 844 : return;
153 : : }
154 : :
155 : : /*
156 : : * Since we've already handled nodes that require pass-through treatment,
157 : : * this should be an unrollable join.
158 : : */
159 : 29759 : strategy = pgpa_decompose_join(walker, plan,
160 : : &realouter, &realinner,
161 : : &elidedouter, &elidedinner,
162 : : &found_any_outer_gather,
163 : : &found_any_inner_gather);
164 : :
165 : : /* If our workspace is full, expand it. */
166 [ + + ]: 29759 : if (join_unroller->nused >= join_unroller->nallocated)
167 : : {
168 : 60 : join_unroller->nallocated *= 2;
169 : 60 : join_unroller->strategy =
170 : 60 : repalloc_array(join_unroller->strategy,
171 : : pgpa_join_strategy,
172 : : join_unroller->nallocated);
173 : 60 : join_unroller->inner_subplans =
174 : 60 : repalloc_array(join_unroller->inner_subplans,
175 : : Plan *,
176 : : join_unroller->nallocated);
177 : 60 : join_unroller->inner_elided_nodes =
178 : 60 : repalloc_array(join_unroller->inner_elided_nodes,
179 : : ElidedNode *,
180 : : join_unroller->nallocated);
181 : 60 : join_unroller->inner_beneath_any_gather =
182 : 60 : repalloc_array(join_unroller->inner_beneath_any_gather,
183 : : bool,
184 : : join_unroller->nallocated);
185 : 60 : join_unroller->inner_unrollers =
186 : 60 : repalloc_array(join_unroller->inner_unrollers,
187 : : pgpa_join_unroller *,
188 : : join_unroller->nallocated);
189 : : }
190 : :
191 : : /*
192 : : * Since we're flattening outer-deep join trees, it follows that if the
193 : : * outer side is still an unrollable join, it should be unrolled into this
194 : : * same object. Otherwise, we've reached the limit of what we can unroll
195 : : * into this object and must remember the outer side as the final outer
196 : : * subplan.
197 : : */
198 [ + + + + ]: 29759 : if (elidedouter == NULL && pgpa_is_join(realouter))
199 : 6338 : *outer_join_unroller = join_unroller;
200 : : else
201 : : {
202 : 23421 : join_unroller->outer_subplan = realouter;
203 : 23421 : join_unroller->outer_elided_node = elidedouter;
204 : 23421 : join_unroller->outer_beneath_any_gather =
205 [ + + + + ]: 23421 : beneath_any_gather || found_any_outer_gather;
206 : : }
207 : :
208 : : /*
209 : : * Store the inner subplan. If it's an unrollable join, it needs to be
210 : : * flattened in turn, but into a new unroller object, not this one.
211 : : */
212 : 29759 : n = join_unroller->nused++;
213 : 29759 : join_unroller->strategy[n] = strategy;
214 : 29759 : join_unroller->inner_subplans[n] = realinner;
215 : 29759 : join_unroller->inner_elided_nodes[n] = elidedinner;
216 : 29759 : join_unroller->inner_beneath_any_gather[n] =
217 [ + + + + ]: 29759 : beneath_any_gather || found_any_inner_gather;
218 [ + + + + ]: 29759 : if (elidedinner == NULL && pgpa_is_join(realinner))
219 : 1029 : *inner_join_unroller = pgpa_create_join_unroller();
220 : : else
221 : 28730 : *inner_join_unroller = NULL;
222 : 29759 : join_unroller->inner_unrollers[n] = *inner_join_unroller;
223 : : }
224 : :
225 : : /*
226 : : * Use the data we've accumulated in a pgpa_join_unroller object to construct
227 : : * a pgpa_unrolled_join.
228 : : */
229 : : pgpa_unrolled_join *
230 : 23421 : pgpa_build_unrolled_join(pgpa_plan_walker_context *walker,
231 : : pgpa_join_unroller *join_unroller)
232 : : {
233 : : pgpa_unrolled_join *ujoin;
234 : : int i;
235 : :
236 : : /*
237 : : * We shouldn't have gone even so far as to create a join unroller unless
238 : : * we found at least one unrollable join.
239 : : */
240 [ - + ]: 23421 : Assert(join_unroller->nused > 0);
241 : :
242 : : /* Allocate result structures. */
243 : 23421 : ujoin = palloc0_object(pgpa_unrolled_join);
244 : 23421 : ujoin->ninner = join_unroller->nused;
245 : 23421 : ujoin->strategy = palloc0_array(pgpa_join_strategy, join_unroller->nused);
246 : 23421 : ujoin->inner = palloc0_array(pgpa_join_member, join_unroller->nused);
247 : :
248 : : /* Handle the outermost join. */
249 : 23421 : ujoin->outer.plan = join_unroller->outer_subplan;
250 : 23421 : ujoin->outer.elided_node = join_unroller->outer_elided_node;
251 : 23421 : ujoin->outer.scan =
252 : 23421 : pgpa_build_scan(walker, ujoin->outer.plan,
253 : : ujoin->outer.elided_node,
254 : 23421 : join_unroller->outer_beneath_any_gather,
255 : : true);
256 : :
257 : : /*
258 : : * We want the joins from the deepest part of the plan tree to appear
259 : : * first in the result object, but the join unroller adds them in exactly
260 : : * the reverse of that order, so we need to flip the order of the arrays
261 : : * when constructing the final result.
262 : : */
263 [ + + ]: 53180 : for (i = 0; i < join_unroller->nused; ++i)
264 : : {
265 : 29759 : int k = join_unroller->nused - i - 1;
266 : :
267 : : /* Copy strategy, Plan, and ElidedNode. */
268 : 29759 : ujoin->strategy[i] = join_unroller->strategy[k];
269 : 29759 : ujoin->inner[i].plan = join_unroller->inner_subplans[k];
270 : 29759 : ujoin->inner[i].elided_node = join_unroller->inner_elided_nodes[k];
271 : :
272 : : /*
273 : : * Fill in remaining details, using either the nested join unroller,
274 : : * or by deriving them from the plan and elided nodes.
275 : : */
276 [ + + ]: 29759 : if (join_unroller->inner_unrollers[k] != NULL)
277 : 1029 : ujoin->inner[i].unrolled_join =
278 : 1029 : pgpa_build_unrolled_join(walker,
279 : 1029 : join_unroller->inner_unrollers[k]);
280 : : else
281 : 28730 : ujoin->inner[i].scan =
282 : 28730 : pgpa_build_scan(walker, ujoin->inner[i].plan,
283 : 28730 : ujoin->inner[i].elided_node,
284 : 28730 : join_unroller->inner_beneath_any_gather[k],
285 : : true);
286 : : }
287 : :
288 : 23421 : return ujoin;
289 : : }
290 : :
291 : : /*
292 : : * Free memory allocated for pgpa_join_unroller.
293 : : */
294 : : void
295 : 22392 : pgpa_destroy_join_unroller(pgpa_join_unroller *join_unroller)
296 : : {
297 : 22392 : pfree(join_unroller->strategy);
298 : 22392 : pfree(join_unroller->inner_subplans);
299 : 22392 : pfree(join_unroller->inner_elided_nodes);
300 : 22392 : pfree(join_unroller->inner_unrollers);
301 : 22392 : pfree(join_unroller->inner_beneath_any_gather);
302 : 22392 : pfree(join_unroller);
303 : 22392 : }
304 : :
305 : : /*
306 : : * Identify the join strategy used by a join and the "real" inner and outer
307 : : * plans.
308 : : *
309 : : * For example, a Hash Join always has a Hash node on the inner side, but
310 : : * for all intents and purposes the real inner input is the Hash node's child,
311 : : * not the Hash node itself.
312 : : *
313 : : * Likewise, a Merge Join may have Sort node on the inner or outer side; if
314 : : * it does, the real input to the join is the Sort node's child, not the
315 : : * Sort node itself.
316 : : *
317 : : * In addition, with a Merge Join or a Nested Loop, the join planning code
318 : : * may add additional nodes such as Materialize or Memoize. We regard these
319 : : * as an aspect of the join strategy. As in the previous cases, the true input
320 : : * to the join is the underlying node.
321 : : *
322 : : * However, if any involved child node previously had a now-elided node stacked
323 : : * on top, then we can't "look through" that node -- indeed, what's going to be
324 : : * relevant for our purposes is the ElidedNode on top of that plan node, rather
325 : : * than the plan node itself.
326 : : *
327 : : * If there are multiple elided nodes, we want that one that would have been
328 : : * uppermost in the plan tree prior to setrefs processing; we expect to find
329 : : * that one last in the list of elided nodes.
330 : : *
331 : : * On return *realouter and *realinner will have been set to the real inner
332 : : * and real outer plans that we identified, and *elidedrealouter and
333 : : * *elidedrealinner to the last of any corresponding elided nodes.
334 : : * Additionally, *found_any_outer_gather and *found_any_inner_gather will
335 : : * be set to true if we looked through a Gather or Gather Merge node on
336 : : * that side of the join, and false otherwise.
337 : : */
338 : : static pgpa_join_strategy
339 : 29759 : pgpa_decompose_join(pgpa_plan_walker_context *walker, Plan *plan,
340 : : Plan **realouter, Plan **realinner,
341 : : ElidedNode **elidedrealouter, ElidedNode **elidedrealinner,
342 : : bool *found_any_outer_gather, bool *found_any_inner_gather)
343 : : {
344 : 29759 : PlannedStmt *pstmt = walker->pstmt;
345 : 29759 : JoinType jointype = ((Join *) plan)->jointype;
346 : 29759 : Plan *outerplan = plan->lefttree;
347 : 29759 : Plan *innerplan = plan->righttree;
348 : : ElidedNode *elidedouter;
349 : : ElidedNode *elidedinner;
350 : : pgpa_join_strategy strategy;
351 : : bool uniqueouter;
352 : : bool uniqueinner;
353 : :
354 : 29759 : elidedouter = pgpa_last_elided_node(pstmt, outerplan);
355 : 29759 : elidedinner = pgpa_last_elided_node(pstmt, innerplan);
356 : 29759 : *found_any_outer_gather = false;
357 : 29759 : *found_any_inner_gather = false;
358 : :
359 [ + + + - ]: 29759 : switch (nodeTag(plan))
360 : : {
361 : 1156 : case T_MergeJoin:
362 : :
363 : : /*
364 : : * The planner may have chosen to place a Material node on the
365 : : * inner side of the MergeJoin; if this is present, we record it
366 : : * as part of the join strategy. (However, scan-level Materialize
367 : : * nodes are an exception.)
368 : : */
22 369 [ + - + + ]: 1156 : if (elidedinner == NULL && IsA(innerplan, Material) &&
370 [ + - ]: 51 : !pgpa_is_scan_level_materialize(innerplan))
371 : : {
54 372 : 51 : elidedinner = pgpa_descend_node(pstmt, &innerplan);
373 : 51 : strategy = JSTRAT_MERGE_JOIN_MATERIALIZE;
374 : : }
375 : : else
376 : 1105 : strategy = JSTRAT_MERGE_JOIN_PLAIN;
377 : :
378 : : /*
379 : : * For a MergeJoin, either the outer or the inner subplan, or
380 : : * both, may have needed to be sorted; we must disregard any Sort
381 : : * or IncrementalSort node to find the real inner or outer
382 : : * subplan.
383 : : */
384 [ + + + + ]: 1156 : if (elidedouter == NULL && is_sorting_plan(outerplan))
385 : 807 : elidedouter = pgpa_descend_node(pstmt, &outerplan);
386 [ + + + + ]: 1156 : if (elidedinner == NULL && is_sorting_plan(innerplan))
387 : 1031 : elidedinner = pgpa_descend_node(pstmt, &innerplan);
388 : 1156 : break;
389 : :
390 : 19853 : case T_NestLoop:
391 : :
392 : : /*
393 : : * The planner may have chosen to place a Material or Memoize node
394 : : * on the inner side of the NestLoop; if this is present, we
395 : : * record it as part of the join strategy. (However, scan-level
396 : : * Materialize nodes are an exception.)
397 : : */
22 398 [ + + + + ]: 19853 : if (elidedinner == NULL && IsA(innerplan, Material) &&
399 [ + + ]: 1017 : !pgpa_is_scan_level_materialize(innerplan))
400 : : {
54 401 : 1016 : elidedinner = pgpa_descend_node(pstmt, &innerplan);
402 : 1016 : strategy = JSTRAT_NESTED_LOOP_MATERIALIZE;
403 : : }
404 [ + + + + ]: 18837 : else if (elidedinner == NULL && IsA(innerplan, Memoize))
405 : : {
406 : 472 : elidedinner = pgpa_descend_node(pstmt, &innerplan);
407 : 472 : strategy = JSTRAT_NESTED_LOOP_MEMOIZE;
408 : : }
409 : : else
410 : 18365 : strategy = JSTRAT_NESTED_LOOP_PLAIN;
411 : 19853 : break;
412 : :
413 : 8750 : case T_HashJoin:
414 : :
415 : : /*
416 : : * The inner subplan of a HashJoin is always a Hash node; the real
417 : : * inner subplan is the Hash node's child.
418 : : */
419 [ - + ]: 8750 : Assert(IsA(innerplan, Hash));
420 [ - + ]: 8750 : Assert(elidedinner == NULL);
421 : 8750 : elidedinner = pgpa_descend_node(pstmt, &innerplan);
422 : 8750 : strategy = JSTRAT_HASH_JOIN;
423 : 8750 : break;
424 : :
54 rhaas@postgresql.org 425 :UNC 0 : default:
426 [ # # ]: 0 : elog(ERROR, "unrecognized node type: %d", (int) nodeTag(plan));
427 : : }
428 : :
429 : : /*
430 : : * The planner may have decided to implement a semijoin by first making
431 : : * the nullable side of the plan unique, and then performing a normal join
432 : : * against the result. Therefore, we might need to descend through a
433 : : * unique node on either side of the plan.
434 : : */
54 rhaas@postgresql.org 435 :GNC 29759 : uniqueouter = pgpa_descend_any_unique(pstmt, &outerplan, &elidedouter);
436 : 29759 : uniqueinner = pgpa_descend_any_unique(pstmt, &innerplan, &elidedinner);
437 : :
438 : : /*
439 : : * Can we see a Result node here, to project above a Gather? So far I've
440 : : * found no example that behaves that way; rather, the Gather or Gather
441 : : * Merge is made to project. Hence, don't test is_result_node_with_child()
442 : : * at this point.
443 : : */
444 : :
445 : : /*
446 : : * The planner may have decided to parallelize part of the join tree, so
447 : : * we could find a Gather or Gather Merge node here. Note that, if
448 : : * present, this will appear below nodes we considered as part of the join
449 : : * strategy, but we could find another uniqueness-enforcing node below the
450 : : * Gather or Gather Merge, if present.
451 : : */
452 [ + + ]: 29759 : if (elidedouter == NULL)
453 : : {
454 : 29586 : elidedouter = pgpa_descend_any_gather(pstmt, &outerplan,
455 : : found_any_outer_gather);
456 [ + + + + ]: 29614 : if (*found_any_outer_gather &&
457 : 28 : pgpa_descend_any_unique(pstmt, &outerplan, &elidedouter))
458 : 2 : uniqueouter = true;
459 : : }
460 [ + + ]: 29759 : if (elidedinner == NULL)
461 : : {
462 : 29400 : elidedinner = pgpa_descend_any_gather(pstmt, &innerplan,
463 : : found_any_inner_gather);
464 [ + + - + ]: 29441 : if (*found_any_inner_gather &&
465 : 41 : pgpa_descend_any_unique(pstmt, &innerplan, &elidedinner))
54 rhaas@postgresql.org 466 :UNC 0 : uniqueinner = true;
467 : : }
468 : :
469 : : /*
470 : : * It's possible that a Result node has been inserted either to project a
471 : : * target list or to implement a one-time filter. If so, we can descend
472 : : * through it. Note that a Result node without a child would be a
473 : : * degenerate scan or join, and not something we could descend through.
474 : : */
54 rhaas@postgresql.org 475 [ + + + + ]:GNC 29759 : if (elidedouter == NULL && is_result_node_with_child(outerplan))
476 : 6 : elidedouter = pgpa_descend_node(pstmt, &outerplan);
477 [ + + + + ]: 29759 : if (elidedinner == NULL && is_result_node_with_child(innerplan))
478 : 6 : elidedinner = pgpa_descend_node(pstmt, &innerplan);
479 : :
480 : : /*
481 : : * If this is a semijoin that was converted to an inner join by making one
482 : : * side or the other unique, make a note that the inner or outer subplan,
483 : : * as appropriate, should be treated as a query plan feature when the main
484 : : * tree traversal reaches it.
485 : : *
486 : : * Conversely, if the planner could have made one side of the join unique
487 : : * and thereby converted it to an inner join, and chose not to do so, that
488 : : * is also worth noting.
489 : : *
490 : : * NB: This code could appear slightly higher up in this function, but
491 : : * none of the nodes through which we just descended should have
492 : : * associated RTIs.
493 : : *
494 : : * NB: This seems like a somewhat hacky way of passing information up to
495 : : * the main tree walk, but I don't currently have a better idea.
496 : : */
497 [ + + ]: 29759 : if (uniqueouter)
498 : 76 : pgpa_add_future_feature(walker, PGPAQF_SEMIJOIN_UNIQUE, outerplan);
499 [ + + ]: 29683 : else if (jointype == JOIN_RIGHT_SEMI)
500 : 73 : pgpa_add_future_feature(walker, PGPAQF_SEMIJOIN_NON_UNIQUE, outerplan);
501 [ + + ]: 29759 : if (uniqueinner)
502 : 78 : pgpa_add_future_feature(walker, PGPAQF_SEMIJOIN_UNIQUE, innerplan);
503 [ + + ]: 29681 : else if (jointype == JOIN_SEMI)
504 : 1230 : pgpa_add_future_feature(walker, PGPAQF_SEMIJOIN_NON_UNIQUE, innerplan);
505 : :
506 : : /* Set output parameters. */
507 : 29759 : *realouter = outerplan;
508 : 29759 : *realinner = innerplan;
509 : 29759 : *elidedrealouter = elidedouter;
510 : 29759 : *elidedrealinner = elidedinner;
511 : 29759 : return strategy;
512 : : }
513 : :
514 : : /*
515 : : * Descend through a Plan node in a join tree that the caller has determined
516 : : * to be irrelevant.
517 : : *
518 : : * Updates *plan, and returns the last of any elided nodes pertaining to the
519 : : * new plan node.
520 : : */
521 : : static ElidedNode *
522 : 12647 : pgpa_descend_node(PlannedStmt *pstmt, Plan **plan)
523 : : {
524 : 12647 : *plan = (*plan)->lefttree;
525 : 12647 : return pgpa_last_elided_node(pstmt, *plan);
526 : : }
527 : :
528 : : /*
529 : : * Descend through a Gather or Gather Merge node, if present, and any Sort
530 : : * or IncrementalSort node occurring under a Gather Merge.
531 : : *
532 : : * Caller should have verified that there is no ElidedNode pertaining to
533 : : * the initial value of *plan.
534 : : *
535 : : * Updates *plan, and returns the last of any elided nodes pertaining to the
536 : : * new plan node. Sets *found_any_gather = true if either Gather or
537 : : * Gather Merge was found, and otherwise leaves it unchanged.
538 : : */
539 : : static ElidedNode *
540 : 58986 : pgpa_descend_any_gather(PlannedStmt *pstmt, Plan **plan,
541 : : bool *found_any_gather)
542 : : {
543 [ + + ]: 58986 : if (IsA(*plan, Gather))
544 : : {
545 : 52 : *found_any_gather = true;
546 : 52 : return pgpa_descend_node(pstmt, plan);
547 : : }
548 : :
549 [ + + ]: 58934 : if (IsA(*plan, GatherMerge))
550 : : {
551 : 17 : ElidedNode *elided = pgpa_descend_node(pstmt, plan);
552 : :
553 [ + - + - ]: 17 : if (elided == NULL && is_sorting_plan(*plan))
554 : 17 : elided = pgpa_descend_node(pstmt, plan);
555 : :
556 : 17 : *found_any_gather = true;
557 : 17 : return elided;
558 : : }
559 : :
560 : 58917 : return NULL;
561 : : }
562 : :
563 : : /*
564 : : * If *plan is an Agg or Unique node, we want to descend through it, unless
565 : : * it has a corresponding elided node. If its immediate child is a Sort or
566 : : * IncrementalSort, we also want to descend through that, unless it has a
567 : : * corresponding elided node.
568 : : *
569 : : * On entry, *elided_node must be the last of any elided nodes corresponding
570 : : * to *plan; on exit, this will still be true, but *plan may have been updated.
571 : : *
572 : : * The reason we don't want to descend through elided nodes is that a single
573 : : * join tree can't cross through any sort of elided node: subqueries are
574 : : * planned separately, and planning inside an Append or MergeAppend is
575 : : * separate from planning outside of it.
576 : : *
577 : : * The return value is true if we descend through a node that we believe is
578 : : * making one side of a semijoin unique, and otherwise false.
579 : : */
580 : : static bool
581 : 59587 : pgpa_descend_any_unique(PlannedStmt *pstmt, Plan **plan,
582 : : ElidedNode **elided_node)
583 : : {
584 : 59587 : bool descend = false;
585 : 59587 : bool sjunique = false;
586 : :
587 [ + + ]: 59587 : if (*elided_node != NULL)
588 : 520 : return sjunique;
589 : :
590 [ + + ]: 59067 : if (IsA(*plan, Unique))
591 : : {
592 : 61 : descend = true;
593 : 61 : sjunique = true;
594 : : }
595 [ + + ]: 59006 : else if (IsA(*plan, Agg))
596 : : {
597 : : /*
598 : : * If this is a simple Agg node, then assume it's here to implement
599 : : * semijoin uniqueness. Otherwise, assume it's completing an eager
600 : : * aggregation or partitionwise aggregation operation that began at a
601 : : * higher level of the plan tree.
602 : : *
603 : : * (Note that when we're using an Agg node for uniqueness, there's no
604 : : * need for any case other than AGGSPLIT_SIMPLE, because there's no
605 : : * aggregated column being computed. However, the fact that
606 : : * AGGSPLIT_SIMPLE is in use doesn't prove that this Agg is here for
607 : : * the semijoin uniqueness. Maybe we should adjust an Agg node to
608 : : * carry a "purpose" field so that code like this can be more certain
609 : : * of its analysis.)
610 : : */
611 : 301 : descend = true;
612 : 301 : sjunique = (((Agg *) *plan)->aggsplit == AGGSPLIT_SIMPLE);
613 : : }
614 : :
615 [ + + ]: 59067 : if (descend)
616 : : {
617 : 362 : *elided_node = pgpa_descend_node(pstmt, plan);
618 : :
619 [ + + + + ]: 362 : if (*elided_node == NULL && is_sorting_plan(*plan))
620 : 60 : *elided_node = pgpa_descend_node(pstmt, plan);
621 : : }
622 : :
623 : 59067 : return sjunique;
624 : : }
625 : :
626 : : /*
627 : : * Is this a Result node that has a child?
628 : : */
629 : : static bool
630 : 88747 : is_result_node_with_child(Plan *plan)
631 : : {
632 [ + + + + ]: 88747 : return IsA(plan, Result) && plan->lefttree != NULL;
633 : : }
634 : :
635 : : /*
636 : : * Is this a Plan node whose purpose is to put the data in a certain order?
637 : : */
638 : : static bool
639 : 32639 : is_sorting_plan(Plan *plan)
640 : : {
641 [ + + + + ]: 32639 : return IsA(plan, Sort) || IsA(plan, IncrementalSort);
642 : : }
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