Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * pgpa_scan.c
4 : : * analysis of scans in Plan trees
5 : : *
6 : : * Copyright (c) 2016-2026, PostgreSQL Global Development Group
7 : : *
8 : : * contrib/pg_plan_advice/pgpa_scan.c
9 : : *
10 : : *-------------------------------------------------------------------------
11 : : */
12 : : #include "postgres.h"
13 : :
14 : : #include "pgpa_scan.h"
15 : : #include "pgpa_walker.h"
16 : :
17 : : #include "nodes/parsenodes.h"
18 : : #include "parser/parsetree.h"
19 : :
20 : : static pgpa_scan *pgpa_make_scan(pgpa_plan_walker_context *walker, Plan *plan,
21 : : pgpa_scan_strategy strategy,
22 : : Bitmapset *relids);
23 : :
24 : :
25 : : static RTEKind unique_nonjoin_rtekind(Bitmapset *relids, List *rtable);
26 : :
27 : : /*
28 : : * Build a pgpa_scan object for a Plan node and update the plan walker
29 : : * context as appropriate. If this is an Append or MergeAppend scan, also
30 : : * build pgpa_scan for any scans that were consolidated into this one by
31 : : * Append/MergeAppend pull-up.
32 : : *
33 : : * If there is at least one ElidedNode for this plan node, pass the uppermost
34 : : * one as elided_node, else pass NULL.
35 : : *
36 : : * Set the 'beneath_any_gather' node if we are underneath a Gather or
37 : : * Gather Merge node (except for a single-copy Gather node, for which
38 : : * GATHER or GATHER_MERGE advice should not be emitted).
39 : : *
40 : : * Set the 'within_join_problem' flag if we're inside of a join problem and
41 : : * not otherwise.
42 : : */
43 : : pgpa_scan *
54 rhaas@postgresql.org 44 :GNC 233813 : pgpa_build_scan(pgpa_plan_walker_context *walker, Plan *plan,
45 : : ElidedNode *elided_node,
46 : : bool beneath_any_gather, bool within_join_problem)
47 : : {
48 : 233813 : pgpa_scan_strategy strategy = PGPA_SCAN_ORDINARY;
49 : 233813 : Bitmapset *relids = NULL;
50 : 233813 : int rti = -1;
51 : 233813 : List *child_append_relid_sets = NIL;
52 : 233813 : NodeTag nodetype = nodeTag(plan);
53 : :
54 [ + + ]: 233813 : if (elided_node != NULL)
55 : : {
56 : 5660 : nodetype = elided_node->elided_type;
57 : 5660 : relids = elided_node->relids;
58 : :
59 : : /*
60 : : * If setrefs processing elided an Append or MergeAppend node that had
61 : : * only one surviving child, it could be either a partitionwise
62 : : * operation or a setop over subqueries, depending on the rtekind.
63 : : *
64 : : * A setop over subqueries, or a trivial SubqueryScan that was elided,
65 : : * is an "ordinary" scan i.e. one for which we do not need to generate
66 : : * advice because the planner has not made any meaningful choice.
67 : : *
68 : : * Note that the PGPA_SCAN_PARTITIONWISE case also includes
69 : : * partitionwise joins; this module considers those to be a form of
70 : : * scan, since they lack internal structure that we can decompose.
71 : : *
72 : : * Note also that it's possible for relids to be NULL here, if the
73 : : * elided Append node is part of a partitionwise aggregate. In that
74 : : * case, it doesn't matter what strategy we choose, but we do need to
75 : : * avoid calling unique_nonjoin_rtekind(), which would fail an
76 : : * assertion.
77 : : */
78 [ + + - + : 5660 : if ((nodetype == T_Append || nodetype == T_MergeAppend) &&
+ - ]
36 79 [ + + ]: 1208 : relids != NULL &&
54 80 : 1208 : unique_nonjoin_rtekind(relids,
81 : 1208 : walker->pstmt->rtable) == RTE_RELATION)
82 : 1196 : strategy = PGPA_SCAN_PARTITIONWISE;
83 : : else
84 : 4464 : strategy = PGPA_SCAN_ORDINARY;
85 : :
86 : : /* Join RTIs can be present, but advice never refers to them. */
87 : 5660 : relids = pgpa_filter_out_join_relids(relids, walker->pstmt->rtable);
88 : : }
89 [ + + ]: 228153 : else if ((rti = pgpa_scanrelid(plan)) != 0)
90 : : {
91 : 101907 : relids = bms_make_singleton(rti);
92 : :
93 [ + + + + : 101907 : switch (nodeTag(plan))
+ + ]
94 : : {
95 : 54272 : case T_SeqScan:
96 : 54272 : strategy = PGPA_SCAN_SEQ;
97 : 54272 : break;
98 : 4645 : case T_BitmapHeapScan:
99 : 4645 : strategy = PGPA_SCAN_BITMAP_HEAP;
100 : 4645 : break;
101 : 24141 : case T_IndexScan:
102 : 24141 : strategy = PGPA_SCAN_INDEX;
103 : 24141 : break;
104 : 3841 : case T_IndexOnlyScan:
105 : 3841 : strategy = PGPA_SCAN_INDEX_ONLY;
106 : 3841 : break;
107 : 840 : case T_TidScan:
108 : : case T_TidRangeScan:
109 : 840 : strategy = PGPA_SCAN_TID;
110 : 840 : break;
111 : 14168 : default:
112 : :
113 : : /*
114 : : * This case includes a ForeignScan targeting a single
115 : : * relation; no other strategy is possible in that case, but
116 : : * see below, where things are different in multi-relation
117 : : * cases.
118 : : */
119 : 14168 : strategy = PGPA_SCAN_ORDINARY;
120 : 14168 : break;
121 : : }
122 : : }
22 123 [ + + ]: 126246 : else if (pgpa_is_scan_level_materialize(plan))
124 : : {
125 : : /*
126 : : * Non-repeatable tablesample methods can be wrapped in a Materialize
127 : : * node that must be treated as part of the scan itself. See
128 : : * set_tablesample_rel_pathlist().
129 : : */
130 : 2 : rti = pgpa_scanrelid(plan->lefttree);
131 : 2 : relids = bms_make_singleton(rti);
132 : 2 : strategy = PGPA_SCAN_ORDINARY;
133 : : }
54 134 [ + + ]: 126244 : else if ((relids = pgpa_relids(plan)) != NULL)
135 : : {
136 [ - + + + ]: 42723 : switch (nodeTag(plan))
137 : : {
54 rhaas@postgresql.org 138 :UNC 0 : case T_ForeignScan:
139 : :
140 : : /*
141 : : * If multiple relations are being targeted by a single
142 : : * foreign scan, then the foreign join has been pushed to the
143 : : * remote side, and we want that to be reflected in the
144 : : * generated advice.
145 : : */
146 : 0 : strategy = PGPA_SCAN_FOREIGN;
147 : 0 : break;
54 rhaas@postgresql.org 148 :GNC 5091 : case T_Append:
149 : :
150 : : /*
151 : : * Append nodes can represent partitionwise scans of a
152 : : * relation, but when they implement a set operation, they are
153 : : * just ordinary scans.
154 : : */
155 [ + + ]: 5091 : if (unique_nonjoin_rtekind(relids, walker->pstmt->rtable)
156 : : == RTE_RELATION)
157 : 2441 : strategy = PGPA_SCAN_PARTITIONWISE;
158 : : else
159 : 2650 : strategy = PGPA_SCAN_ORDINARY;
160 : :
161 : : /* Be sure to account for pulled-up scans. */
162 : 5091 : child_append_relid_sets =
163 : : ((Append *) plan)->child_append_relid_sets;
164 : 5091 : break;
165 : 162 : case T_MergeAppend:
166 : : /* Same logic here as for Append, above. */
167 [ + + ]: 162 : if (unique_nonjoin_rtekind(relids, walker->pstmt->rtable)
168 : : == RTE_RELATION)
169 : 96 : strategy = PGPA_SCAN_PARTITIONWISE;
170 : : else
171 : 66 : strategy = PGPA_SCAN_ORDINARY;
172 : :
173 : : /* Be sure to account for pulled-up scans. */
174 : 162 : child_append_relid_sets =
175 : : ((MergeAppend *) plan)->child_append_relid_sets;
176 : 162 : break;
177 : 37470 : default:
178 : 37470 : strategy = PGPA_SCAN_ORDINARY;
179 : 37470 : break;
180 : : }
181 : :
182 : :
183 : : /* Join RTIs can be present, but advice never refers to them. */
184 : 42723 : relids = pgpa_filter_out_join_relids(relids, walker->pstmt->rtable);
185 : : }
186 : :
187 : : /*
188 : : * If this is an Append or MergeAppend node into which subordinate Append
189 : : * or MergeAppend paths were merged, each of those merged paths is
190 : : * effectively another scan for which we need to account.
191 : : */
192 [ + + + + : 468364 : foreach_node(Bitmapset, child_relids, child_append_relid_sets)
+ + ]
193 : : {
194 : : Bitmapset *child_nonjoin_relids;
195 : :
196 : : child_nonjoin_relids =
197 : 738 : pgpa_filter_out_join_relids(child_relids,
198 : 738 : walker->pstmt->rtable);
199 : 738 : (void) pgpa_make_scan(walker, plan, strategy,
200 : : child_nonjoin_relids);
201 : : }
202 : :
203 : : /*
204 : : * If this plan node has no associated RTIs, it's not a scan. When the
205 : : * 'within_join_problem' flag is set, that's unexpected, so throw an
206 : : * error, else return quietly.
207 : : */
208 [ + + ]: 233813 : if (relids == NULL)
209 : : {
210 [ - + ]: 83521 : if (within_join_problem)
54 rhaas@postgresql.org 211 [ # # ]:UNC 0 : elog(ERROR, "plan node has no RTIs: %d", (int) nodeTag(plan));
54 rhaas@postgresql.org 212 :GNC 83521 : return NULL;
213 : : }
214 : :
215 : : /*
216 : : * Add the appropriate set of RTIs to walker->no_gather_scans.
217 : : *
218 : : * Add nothing if we're beneath a Gather or Gather Merge node, since
219 : : * NO_GATHER advice is clearly inappropriate in that situation.
220 : : *
221 : : * Add nothing if this is an Append or MergeAppend node, whether or not
222 : : * elided. We'll emit NO_GATHER() for the underlying scan, which is good
223 : : * enough.
224 : : */
225 [ + + + + : 150292 : if (!beneath_any_gather && nodetype != T_Append &&
+ + ]
226 : : nodetype != T_MergeAppend)
227 : 142414 : walker->no_gather_scans =
228 : 142414 : bms_add_members(walker->no_gather_scans, relids);
229 : :
230 : : /* Caller tells us whether NO_GATHER() advice for this scan is needed. */
231 : 150292 : return pgpa_make_scan(walker, plan, strategy, relids);
232 : : }
233 : :
234 : : /*
235 : : * Create a single pgpa_scan object and update the pgpa_plan_walker_context.
236 : : */
237 : : static pgpa_scan *
238 : 151030 : pgpa_make_scan(pgpa_plan_walker_context *walker, Plan *plan,
239 : : pgpa_scan_strategy strategy, Bitmapset *relids)
240 : : {
241 : : pgpa_scan *scan;
242 : :
243 : : /* Create the scan object. */
244 : 151030 : scan = palloc(sizeof(pgpa_scan));
245 : 151030 : scan->plan = plan;
246 : 151030 : scan->strategy = strategy;
247 : 151030 : scan->relids = relids;
248 : :
249 : : /* Add it to the appropriate list. */
250 : 151030 : walker->scans[scan->strategy] = lappend(walker->scans[scan->strategy],
251 : : scan);
252 : :
253 : 151030 : return scan;
254 : : }
255 : :
256 : : /*
257 : : * Determine the unique rtekind of a set of relids.
258 : : */
259 : : static RTEKind
260 : 6461 : unique_nonjoin_rtekind(Bitmapset *relids, List *rtable)
261 : : {
262 : 6461 : int rti = -1;
263 : 6461 : bool first = true;
53 nathan@postgresql.or 264 : 6461 : RTEKind rtekind = RTE_RELATION; /* silence compiler warning */
265 : :
54 rhaas@postgresql.org 266 [ - + ]: 6461 : Assert(relids != NULL);
267 : :
268 [ + + ]: 15935 : while ((rti = bms_next_member(relids, rti)) >= 0)
269 : : {
270 : 9474 : RangeTblEntry *rte = rt_fetch(rti, rtable);
271 : :
272 [ + + ]: 9474 : if (rte->rtekind == RTE_JOIN)
273 : 182 : continue;
274 : :
275 [ + + ]: 9292 : if (first)
276 : : {
277 : 6461 : rtekind = rte->rtekind;
278 : 6461 : first = false;
279 : : }
280 [ - + ]: 2831 : else if (rtekind != rte->rtekind)
54 rhaas@postgresql.org 281 [ # # ]:UNC 0 : elog(ERROR, "rtekind mismatch: %d vs. %d",
282 : : rtekind, rte->rtekind);
283 : : }
284 : :
54 rhaas@postgresql.org 285 [ - + ]:GNC 6461 : if (first)
54 rhaas@postgresql.org 286 [ # # ]:UNC 0 : elog(ERROR, "no non-RTE_JOIN RTEs found");
287 : :
54 rhaas@postgresql.org 288 :GNC 6461 : return rtekind;
289 : : }
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