Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * preptlist.c
4 : * Routines to preprocess the parse tree target list
5 : *
6 : * For an INSERT, the targetlist must contain an entry for each attribute of
7 : * the target relation in the correct order.
8 : *
9 : * For an UPDATE, the targetlist just contains the expressions for the new
10 : * column values.
11 : *
12 : * For UPDATE and DELETE queries, the targetlist must also contain "junk"
13 : * tlist entries needed to allow the executor to identify the rows to be
14 : * updated or deleted; for example, the ctid of a heap row. (The planner
15 : * adds these; they're not in what we receive from the parser/rewriter.)
16 : *
17 : * For all query types, there can be additional junk tlist entries, such as
18 : * sort keys, Vars needed for a RETURNING list, and row ID information needed
19 : * for SELECT FOR UPDATE locking and/or EvalPlanQual checking.
20 : *
21 : * The query rewrite phase also does preprocessing of the targetlist (see
22 : * rewriteTargetListIU). The division of labor between here and there is
23 : * partially historical, but it's not entirely arbitrary. The stuff done
24 : * here is closely connected to physical access to tables, whereas the
25 : * rewriter's work is more concerned with SQL semantics.
26 : *
27 : *
28 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
29 : * Portions Copyright (c) 1994, Regents of the University of California
30 : *
31 : * IDENTIFICATION
32 : * src/backend/optimizer/prep/preptlist.c
33 : *
34 : *-------------------------------------------------------------------------
35 : */
36 :
37 : #include "postgres.h"
38 :
39 : #include "access/table.h"
40 : #include "nodes/makefuncs.h"
41 : #include "optimizer/appendinfo.h"
42 : #include "optimizer/optimizer.h"
43 : #include "optimizer/prep.h"
44 : #include "optimizer/tlist.h"
45 : #include "parser/parse_coerce.h"
46 : #include "parser/parsetree.h"
47 : #include "utils/lsyscache.h"
48 : #include "utils/rel.h"
49 :
50 : static List *expand_insert_targetlist(PlannerInfo *root, List *tlist,
51 : Relation rel);
52 :
53 :
54 : /*
55 : * preprocess_targetlist
56 : * Driver for preprocessing the parse tree targetlist.
57 : *
58 : * The preprocessed targetlist is returned in root->processed_tlist.
59 : * Also, if this is an UPDATE, we return a list of target column numbers
60 : * in root->update_colnos. (Resnos in processed_tlist will be consecutive,
61 : * so do not look at that to find out which columns are targets!)
62 : */
63 : void
64 279704 : preprocess_targetlist(PlannerInfo *root)
65 : {
66 279704 : Query *parse = root->parse;
67 279704 : int result_relation = parse->resultRelation;
68 279704 : List *range_table = parse->rtable;
69 279704 : CmdType command_type = parse->commandType;
70 279704 : RangeTblEntry *target_rte = NULL;
71 279704 : Relation target_relation = NULL;
72 : List *tlist;
73 : ListCell *lc;
74 :
75 : /*
76 : * If there is a result relation, open it so we can look for missing
77 : * columns and so on. We assume that previous code already acquired at
78 : * least AccessShareLock on the relation, so we need no lock here.
79 : */
80 279704 : if (result_relation)
81 : {
82 47987 : target_rte = rt_fetch(result_relation, range_table);
83 :
84 : /*
85 : * Sanity check: it'd better be a real relation not, say, a subquery.
86 : * Else parser or rewriter messed up.
87 : */
88 47987 : if (target_rte->rtekind != RTE_RELATION)
89 0 : elog(ERROR, "result relation must be a regular relation");
90 :
91 47987 : target_relation = table_open(target_rte->relid, NoLock);
92 : }
93 : else
94 : Assert(command_type == CMD_SELECT);
95 :
96 : /*
97 : * In an INSERT, the executor expects the targetlist to match the exact
98 : * order of the target table's attributes, including entries for
99 : * attributes not mentioned in the source query.
100 : *
101 : * In an UPDATE, we don't rearrange the tlist order, but we need to make a
102 : * separate list of the target attribute numbers, in tlist order, and then
103 : * renumber the processed_tlist entries to be consecutive.
104 : */
105 279704 : tlist = parse->targetList;
106 279704 : if (command_type == CMD_INSERT)
107 37480 : tlist = expand_insert_targetlist(root, tlist, target_relation);
108 242224 : else if (command_type == CMD_UPDATE)
109 7382 : root->update_colnos = extract_update_targetlist_colnos(tlist);
110 :
111 : /*
112 : * For non-inherited UPDATE/DELETE/MERGE, register any junk column(s)
113 : * needed to allow the executor to identify the rows to be updated or
114 : * deleted. In the inheritance case, we do nothing now, leaving this to
115 : * be dealt with when expand_inherited_rtentry() makes the leaf target
116 : * relations. (But there might not be any leaf target relations, in which
117 : * case we must do this in distribute_row_identity_vars().)
118 : */
119 279704 : if ((command_type == CMD_UPDATE || command_type == CMD_DELETE ||
120 10507 : command_type == CMD_MERGE) &&
121 10507 : !target_rte->inh)
122 : {
123 : /* row-identity logic expects to add stuff to processed_tlist */
124 9031 : root->processed_tlist = tlist;
125 9031 : add_row_identity_columns(root, result_relation,
126 : target_rte, target_relation);
127 9031 : tlist = root->processed_tlist;
128 : }
129 :
130 : /*
131 : * For MERGE we also need to handle the target list for each INSERT and
132 : * UPDATE action separately. In addition, we examine the qual of each
133 : * action and add any Vars there (other than those of the target rel) to
134 : * the subplan targetlist.
135 : */
136 279704 : if (command_type == CMD_MERGE)
137 : {
138 : ListCell *l;
139 : List *vars;
140 :
141 : /*
142 : * For MERGE, handle targetlist of each MergeAction separately. Give
143 : * the same treatment to MergeAction->targetList as we would have
144 : * given to a regular INSERT. For UPDATE, collect the column numbers
145 : * being modified.
146 : */
147 2368 : foreach(l, parse->mergeActionList)
148 : {
149 1441 : MergeAction *action = (MergeAction *) lfirst(l);
150 : ListCell *l2;
151 :
152 1441 : if (action->commandType == CMD_INSERT)
153 473 : action->targetList = expand_insert_targetlist(root,
154 : action->targetList,
155 : target_relation);
156 968 : else if (action->commandType == CMD_UPDATE)
157 694 : action->updateColnos =
158 694 : extract_update_targetlist_colnos(action->targetList);
159 :
160 : /*
161 : * Add resjunk entries for any Vars and PlaceHolderVars used in
162 : * each action's targetlist and WHEN condition that belong to
163 : * relations other than the target. We don't expect to see any
164 : * aggregates or window functions here.
165 : */
166 1441 : vars = pull_var_clause((Node *)
167 1441 : list_concat_copy((List *) action->qual,
168 1441 : action->targetList),
169 : PVC_INCLUDE_PLACEHOLDERS);
170 3244 : foreach(l2, vars)
171 : {
172 1803 : Var *var = (Var *) lfirst(l2);
173 : TargetEntry *tle;
174 :
175 1803 : if (IsA(var, Var) && var->varno == result_relation)
176 894 : continue; /* don't need it */
177 :
178 909 : if (tlist_member((Expr *) var, tlist))
179 244 : continue; /* already got it */
180 :
181 665 : tle = makeTargetEntry((Expr *) var,
182 665 : list_length(tlist) + 1,
183 : NULL, true);
184 665 : tlist = lappend(tlist, tle);
185 : }
186 1441 : list_free(vars);
187 : }
188 :
189 : /*
190 : * Add resjunk entries for any Vars and PlaceHolderVars used in the
191 : * join condition that belong to relations other than the target. We
192 : * don't expect to see any aggregates or window functions here.
193 : */
194 927 : vars = pull_var_clause(parse->mergeJoinCondition,
195 : PVC_INCLUDE_PLACEHOLDERS);
196 1131 : foreach(l, vars)
197 : {
198 204 : Var *var = (Var *) lfirst(l);
199 : TargetEntry *tle;
200 :
201 204 : if (IsA(var, Var) && var->varno == result_relation)
202 69 : continue; /* don't need it */
203 :
204 135 : if (tlist_member((Expr *) var, tlist))
205 54 : continue; /* already got it */
206 :
207 81 : tle = makeTargetEntry((Expr *) var,
208 81 : list_length(tlist) + 1,
209 : NULL, true);
210 81 : tlist = lappend(tlist, tle);
211 : }
212 : }
213 :
214 : /*
215 : * Add necessary junk columns for rowmarked rels. These values are needed
216 : * for locking of rels selected FOR UPDATE/SHARE, and to do EvalPlanQual
217 : * rechecking. See comments for PlanRowMark in plannodes.h. If you
218 : * change this stanza, see also expand_inherited_rtentry(), which has to
219 : * be able to add on junk columns equivalent to these.
220 : *
221 : * (Someday it might be useful to fold these resjunk columns into the
222 : * row-identity-column management used for UPDATE/DELETE. Today is not
223 : * that day, however. One notable issue is that it seems important that
224 : * the whole-row Vars made here use the real table rowtype, not RECORD, so
225 : * that conversion to/from child relations' rowtypes will happen. Also,
226 : * since these entries don't potentially bloat with more and more child
227 : * relations, there's not really much need for column sharing.)
228 : */
229 288003 : foreach(lc, root->rowMarks)
230 : {
231 8299 : PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
232 : Var *var;
233 : char resname[32];
234 : TargetEntry *tle;
235 :
236 : /* child rels use the same junk attrs as their parents */
237 8299 : if (rc->rti != rc->prti)
238 0 : continue;
239 :
240 8299 : if (rc->allMarkTypes & ~(1 << ROW_MARK_COPY))
241 : {
242 : /* Need to fetch TID */
243 7920 : var = makeVar(rc->rti,
244 : SelfItemPointerAttributeNumber,
245 : TIDOID,
246 : -1,
247 : InvalidOid,
248 : 0);
249 7920 : snprintf(resname, sizeof(resname), "ctid%u", rc->rowmarkId);
250 7920 : tle = makeTargetEntry((Expr *) var,
251 7920 : list_length(tlist) + 1,
252 : pstrdup(resname),
253 : true);
254 7920 : tlist = lappend(tlist, tle);
255 : }
256 8299 : if (rc->allMarkTypes & (1 << ROW_MARK_COPY))
257 : {
258 : /* Need the whole row as a junk var */
259 379 : var = makeWholeRowVar(rt_fetch(rc->rti, range_table),
260 379 : rc->rti,
261 : 0,
262 : false);
263 379 : snprintf(resname, sizeof(resname), "wholerow%u", rc->rowmarkId);
264 379 : tle = makeTargetEntry((Expr *) var,
265 379 : list_length(tlist) + 1,
266 : pstrdup(resname),
267 : true);
268 379 : tlist = lappend(tlist, tle);
269 : }
270 :
271 : /* If parent of inheritance tree, always fetch the tableoid too. */
272 8299 : if (rc->isParent)
273 : {
274 0 : var = makeVar(rc->rti,
275 : TableOidAttributeNumber,
276 : OIDOID,
277 : -1,
278 : InvalidOid,
279 : 0);
280 0 : snprintf(resname, sizeof(resname), "tableoid%u", rc->rowmarkId);
281 0 : tle = makeTargetEntry((Expr *) var,
282 0 : list_length(tlist) + 1,
283 : pstrdup(resname),
284 : true);
285 0 : tlist = lappend(tlist, tle);
286 : }
287 : }
288 :
289 : /*
290 : * If the query has a RETURNING list, add resjunk entries for any Vars
291 : * used in RETURNING that belong to other relations. We need to do this
292 : * to make these Vars available for the RETURNING calculation. Vars that
293 : * belong to the result rel don't need to be added, because they will be
294 : * made to refer to the actual heap tuple.
295 : */
296 279704 : if (parse->returningList && list_length(parse->rtable) > 1)
297 : {
298 : List *vars;
299 : ListCell *l;
300 :
301 1124 : vars = pull_var_clause((Node *) parse->returningList,
302 : PVC_RECURSE_AGGREGATES |
303 : PVC_RECURSE_WINDOWFUNCS |
304 : PVC_INCLUDE_PLACEHOLDERS);
305 4826 : foreach(l, vars)
306 : {
307 3702 : Var *var = (Var *) lfirst(l);
308 : TargetEntry *tle;
309 :
310 3702 : if (IsA(var, Var) &&
311 3702 : var->varno == result_relation)
312 3372 : continue; /* don't need it */
313 :
314 330 : if (tlist_member((Expr *) var, tlist))
315 118 : continue; /* already got it */
316 :
317 212 : tle = makeTargetEntry((Expr *) var,
318 212 : list_length(tlist) + 1,
319 : NULL,
320 : true);
321 :
322 212 : tlist = lappend(tlist, tle);
323 : }
324 1124 : list_free(vars);
325 : }
326 :
327 279704 : root->processed_tlist = tlist;
328 :
329 279704 : if (target_relation)
330 47987 : table_close(target_relation, NoLock);
331 279704 : }
332 :
333 : /*
334 : * extract_update_targetlist_colnos
335 : * Extract a list of the target-table column numbers that
336 : * an UPDATE's targetlist wants to assign to, then renumber.
337 : *
338 : * The convention in the parser and rewriter is that the resnos in an
339 : * UPDATE's non-resjunk TLE entries are the target column numbers
340 : * to assign to. Here, we extract that info into a separate list, and
341 : * then convert the tlist to the sequential-numbering convention that's
342 : * used by all other query types.
343 : *
344 : * This is also applied to the tlist associated with INSERT ... ON CONFLICT
345 : * ... UPDATE, although not till much later in planning.
346 : */
347 : List *
348 9222 : extract_update_targetlist_colnos(List *tlist)
349 : {
350 9222 : List *update_colnos = NIL;
351 9222 : AttrNumber nextresno = 1;
352 : ListCell *lc;
353 :
354 20446 : foreach(lc, tlist)
355 : {
356 11224 : TargetEntry *tle = (TargetEntry *) lfirst(lc);
357 :
358 11224 : if (!tle->resjunk)
359 11080 : update_colnos = lappend_int(update_colnos, tle->resno);
360 11224 : tle->resno = nextresno++;
361 : }
362 9222 : return update_colnos;
363 : }
364 :
365 :
366 : /*****************************************************************************
367 : *
368 : * TARGETLIST EXPANSION
369 : *
370 : *****************************************************************************/
371 :
372 : /*
373 : * expand_insert_targetlist
374 : * Given a target list as generated by the parser and a result relation,
375 : * add targetlist entries for any missing attributes, and ensure the
376 : * non-junk attributes appear in proper field order.
377 : *
378 : * Once upon a time we also did more or less this with UPDATE targetlists,
379 : * but now this code is only applied to INSERT targetlists.
380 : */
381 : static List *
382 37953 : expand_insert_targetlist(PlannerInfo *root, List *tlist, Relation rel)
383 : {
384 37953 : List *new_tlist = NIL;
385 : ListCell *tlist_item;
386 : int attrno,
387 : numattrs;
388 :
389 37953 : tlist_item = list_head(tlist);
390 :
391 : /*
392 : * The rewriter should have already ensured that the TLEs are in correct
393 : * order; but we have to insert TLEs for any missing attributes.
394 : *
395 : * Scan the tuple description in the relation's relcache entry to make
396 : * sure we have all the user attributes in the right order.
397 : */
398 37953 : numattrs = RelationGetNumberOfAttributes(rel);
399 :
400 123405 : for (attrno = 1; attrno <= numattrs; attrno++)
401 : {
402 85452 : Form_pg_attribute att_tup = TupleDescAttr(rel->rd_att, attrno - 1);
403 85452 : TargetEntry *new_tle = NULL;
404 :
405 85452 : if (tlist_item != NULL)
406 : {
407 80158 : TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
408 :
409 80158 : if (!old_tle->resjunk && old_tle->resno == attrno)
410 : {
411 75606 : new_tle = old_tle;
412 75606 : tlist_item = lnext(tlist, tlist_item);
413 : }
414 : }
415 :
416 85452 : if (new_tle == NULL)
417 : {
418 : /*
419 : * Didn't find a matching tlist entry, so make one.
420 : *
421 : * INSERTs should insert NULL in this case. (We assume the
422 : * rewriter would have inserted any available non-NULL default
423 : * value.) Also, normally we must apply any domain constraints
424 : * that might exist --- this is to catch domain NOT NULL.
425 : *
426 : * When generating a NULL constant for a dropped column, we label
427 : * it INT4 (any other guaranteed-to-exist datatype would do as
428 : * well). We can't label it with the dropped column's datatype
429 : * since that might not exist anymore. It does not really matter
430 : * what we claim the type is, since NULL is NULL --- its
431 : * representation is datatype-independent. This could perhaps
432 : * confuse code comparing the finished plan to the target
433 : * relation, however.
434 : *
435 : * Another exception is that if the column is generated, the value
436 : * we produce here will be ignored, and we don't want to risk
437 : * throwing an error. So in that case we *don't* want to apply
438 : * domain constraints, so we must produce a NULL of the base type.
439 : * Again, code comparing the finished plan to the target relation
440 : * must account for this.
441 : */
442 : Node *new_expr;
443 :
444 9846 : if (att_tup->attisdropped)
445 : {
446 : /* Insert NULL for dropped column */
447 344 : new_expr = (Node *) makeConst(INT4OID,
448 : -1,
449 : InvalidOid,
450 : sizeof(int32),
451 : (Datum) 0,
452 : true, /* isnull */
453 : true /* byval */ );
454 : }
455 9502 : else if (att_tup->attgenerated)
456 : {
457 : /* Generated column, insert a NULL of the base type */
458 619 : Oid baseTypeId = att_tup->atttypid;
459 619 : int32 baseTypeMod = att_tup->atttypmod;
460 :
461 619 : baseTypeId = getBaseTypeAndTypmod(baseTypeId, &baseTypeMod);
462 619 : new_expr = (Node *) makeConst(baseTypeId,
463 : baseTypeMod,
464 : att_tup->attcollation,
465 619 : att_tup->attlen,
466 : (Datum) 0,
467 : true, /* isnull */
468 619 : att_tup->attbyval);
469 : }
470 : else
471 : {
472 : /* Normal column, insert a NULL of the column datatype */
473 8883 : new_expr = coerce_null_to_domain(att_tup->atttypid,
474 : att_tup->atttypmod,
475 : att_tup->attcollation,
476 8883 : att_tup->attlen,
477 8883 : att_tup->attbyval);
478 : /* Must run expression preprocessing on any non-const nodes */
479 8883 : if (!IsA(new_expr, Const))
480 33 : new_expr = eval_const_expressions(root, new_expr);
481 : }
482 :
483 9846 : new_tle = makeTargetEntry((Expr *) new_expr,
484 : attrno,
485 9846 : pstrdup(NameStr(att_tup->attname)),
486 : false);
487 : }
488 :
489 85452 : new_tlist = lappend(new_tlist, new_tle);
490 : }
491 :
492 : /*
493 : * The remaining tlist entries should be resjunk; append them all to the
494 : * end of the new tlist, making sure they have resnos higher than the last
495 : * real attribute. (Note: although the rewriter already did such
496 : * renumbering, we have to do it again here in case we added NULL entries
497 : * above.)
498 : */
499 37953 : while (tlist_item)
500 : {
501 0 : TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
502 :
503 0 : if (!old_tle->resjunk)
504 0 : elog(ERROR, "targetlist is not sorted correctly");
505 : /* Get the resno right, but don't copy unnecessarily */
506 0 : if (old_tle->resno != attrno)
507 : {
508 0 : old_tle = flatCopyTargetEntry(old_tle);
509 0 : old_tle->resno = attrno;
510 : }
511 0 : new_tlist = lappend(new_tlist, old_tle);
512 0 : attrno++;
513 0 : tlist_item = lnext(tlist, tlist_item);
514 : }
515 :
516 37953 : return new_tlist;
517 : }
518 :
519 :
520 : /*
521 : * Locate PlanRowMark for given RT index, or return NULL if none
522 : *
523 : * This probably ought to be elsewhere, but there's no very good place
524 : */
525 : PlanRowMark *
526 12120 : get_plan_rowmark(List *rowmarks, Index rtindex)
527 : {
528 : ListCell *l;
529 :
530 12938 : foreach(l, rowmarks)
531 : {
532 2075 : PlanRowMark *rc = (PlanRowMark *) lfirst(l);
533 :
534 2075 : if (rc->rti == rtindex)
535 1257 : return rc;
536 : }
537 10863 : return NULL;
538 : }
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