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) 1996-2024, 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/rel.h"
48 :
49 : static List *expand_insert_targetlist(List *tlist, Relation rel);
50 :
51 :
52 : /*
53 : * preprocess_targetlist
54 : * Driver for preprocessing the parse tree targetlist.
55 : *
56 : * The preprocessed targetlist is returned in root->processed_tlist.
57 : * Also, if this is an UPDATE, we return a list of target column numbers
58 : * in root->update_colnos. (Resnos in processed_tlist will be consecutive,
59 : * so do not look at that to find out which columns are targets!)
60 : */
61 : void
62 505632 : preprocess_targetlist(PlannerInfo *root)
63 : {
64 505632 : Query *parse = root->parse;
65 505632 : int result_relation = parse->resultRelation;
66 505632 : List *range_table = parse->rtable;
67 505632 : CmdType command_type = parse->commandType;
68 505632 : RangeTblEntry *target_rte = NULL;
69 505632 : Relation target_relation = NULL;
70 : List *tlist;
71 : ListCell *lc;
72 :
73 : /*
74 : * If there is a result relation, open it so we can look for missing
75 : * columns and so on. We assume that previous code already acquired at
76 : * least AccessShareLock on the relation, so we need no lock here.
77 : */
78 505632 : if (result_relation)
79 : {
80 90330 : target_rte = rt_fetch(result_relation, range_table);
81 :
82 : /*
83 : * Sanity check: it'd better be a real relation not, say, a subquery.
84 : * Else parser or rewriter messed up.
85 : */
86 90330 : if (target_rte->rtekind != RTE_RELATION)
87 0 : elog(ERROR, "result relation must be a regular relation");
88 :
89 90330 : target_relation = table_open(target_rte->relid, NoLock);
90 : }
91 : else
92 : Assert(command_type == CMD_SELECT);
93 :
94 : /*
95 : * In an INSERT, the executor expects the targetlist to match the exact
96 : * order of the target table's attributes, including entries for
97 : * attributes not mentioned in the source query.
98 : *
99 : * In an UPDATE, we don't rearrange the tlist order, but we need to make a
100 : * separate list of the target attribute numbers, in tlist order, and then
101 : * renumber the processed_tlist entries to be consecutive.
102 : */
103 505632 : tlist = parse->targetList;
104 505632 : if (command_type == CMD_INSERT)
105 71178 : tlist = expand_insert_targetlist(tlist, target_relation);
106 434454 : else if (command_type == CMD_UPDATE)
107 13090 : root->update_colnos = extract_update_targetlist_colnos(tlist);
108 :
109 : /*
110 : * For non-inherited UPDATE/DELETE/MERGE, register any junk column(s)
111 : * needed to allow the executor to identify the rows to be updated or
112 : * deleted. In the inheritance case, we do nothing now, leaving this to
113 : * be dealt with when expand_inherited_rtentry() makes the leaf target
114 : * relations. (But there might not be any leaf target relations, in which
115 : * case we must do this in distribute_row_identity_vars().)
116 : */
117 505632 : if ((command_type == CMD_UPDATE || command_type == CMD_DELETE ||
118 19152 : command_type == CMD_MERGE) &&
119 19152 : !target_rte->inh)
120 : {
121 : /* row-identity logic expects to add stuff to processed_tlist */
122 16528 : root->processed_tlist = tlist;
123 16528 : add_row_identity_columns(root, result_relation,
124 : target_rte, target_relation);
125 16528 : tlist = root->processed_tlist;
126 : }
127 :
128 : /*
129 : * For MERGE we also need to handle the target list for each INSERT and
130 : * UPDATE action separately. In addition, we examine the qual of each
131 : * action and add any Vars there (other than those of the target rel) to
132 : * the subplan targetlist.
133 : */
134 505632 : if (command_type == CMD_MERGE)
135 : {
136 : ListCell *l;
137 : List *vars;
138 :
139 : /*
140 : * For MERGE, handle targetlist of each MergeAction separately. Give
141 : * the same treatment to MergeAction->targetList as we would have
142 : * given to a regular INSERT. For UPDATE, collect the column numbers
143 : * being modified.
144 : */
145 4452 : foreach(l, parse->mergeActionList)
146 : {
147 2694 : MergeAction *action = (MergeAction *) lfirst(l);
148 : ListCell *l2;
149 :
150 2694 : if (action->commandType == CMD_INSERT)
151 842 : action->targetList = expand_insert_targetlist(action->targetList,
152 : target_relation);
153 1852 : else if (action->commandType == CMD_UPDATE)
154 1376 : action->updateColnos =
155 1376 : extract_update_targetlist_colnos(action->targetList);
156 :
157 : /*
158 : * Add resjunk entries for any Vars and PlaceHolderVars used in
159 : * each action's targetlist and WHEN condition that belong to
160 : * relations other than the target. We don't expect to see any
161 : * aggregates or window functions here.
162 : */
163 2694 : vars = pull_var_clause((Node *)
164 2694 : list_concat_copy((List *) action->qual,
165 2694 : action->targetList),
166 : PVC_INCLUDE_PLACEHOLDERS);
167 6138 : foreach(l2, vars)
168 : {
169 3444 : Var *var = (Var *) lfirst(l2);
170 : TargetEntry *tle;
171 :
172 3444 : if (IsA(var, Var) && var->varno == result_relation)
173 1682 : continue; /* don't need it */
174 :
175 1762 : if (tlist_member((Expr *) var, tlist))
176 476 : continue; /* already got it */
177 :
178 1286 : tle = makeTargetEntry((Expr *) var,
179 1286 : list_length(tlist) + 1,
180 : NULL, true);
181 1286 : tlist = lappend(tlist, tle);
182 : }
183 2694 : list_free(vars);
184 : }
185 :
186 : /*
187 : * Add resjunk entries for any Vars and PlaceHolderVars used in the
188 : * join condition that belong to relations other than the target. We
189 : * don't expect to see any aggregates or window functions here.
190 : */
191 1758 : vars = pull_var_clause(parse->mergeJoinCondition,
192 : PVC_INCLUDE_PLACEHOLDERS);
193 2148 : foreach(l, vars)
194 : {
195 390 : Var *var = (Var *) lfirst(l);
196 : TargetEntry *tle;
197 :
198 390 : if (IsA(var, Var) && var->varno == result_relation)
199 132 : continue; /* don't need it */
200 :
201 258 : if (tlist_member((Expr *) var, tlist))
202 102 : continue; /* already got it */
203 :
204 156 : tle = makeTargetEntry((Expr *) var,
205 156 : list_length(tlist) + 1,
206 : NULL, true);
207 156 : tlist = lappend(tlist, tle);
208 : }
209 : }
210 :
211 : /*
212 : * Add necessary junk columns for rowmarked rels. These values are needed
213 : * for locking of rels selected FOR UPDATE/SHARE, and to do EvalPlanQual
214 : * rechecking. See comments for PlanRowMark in plannodes.h. If you
215 : * change this stanza, see also expand_inherited_rtentry(), which has to
216 : * be able to add on junk columns equivalent to these.
217 : *
218 : * (Someday it might be useful to fold these resjunk columns into the
219 : * row-identity-column management used for UPDATE/DELETE. Today is not
220 : * that day, however. One notable issue is that it seems important that
221 : * the whole-row Vars made here use the real table rowtype, not RECORD, so
222 : * that conversion to/from child relations' rowtypes will happen. Also,
223 : * since these entries don't potentially bloat with more and more child
224 : * relations, there's not really much need for column sharing.)
225 : */
226 516096 : foreach(lc, root->rowMarks)
227 : {
228 10464 : PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
229 : Var *var;
230 : char resname[32];
231 : TargetEntry *tle;
232 :
233 : /* child rels use the same junk attrs as their parents */
234 10464 : if (rc->rti != rc->prti)
235 0 : continue;
236 :
237 10464 : if (rc->allMarkTypes & ~(1 << ROW_MARK_COPY))
238 : {
239 : /* Need to fetch TID */
240 9786 : var = makeVar(rc->rti,
241 : SelfItemPointerAttributeNumber,
242 : TIDOID,
243 : -1,
244 : InvalidOid,
245 : 0);
246 9786 : snprintf(resname, sizeof(resname), "ctid%u", rc->rowmarkId);
247 9786 : tle = makeTargetEntry((Expr *) var,
248 9786 : list_length(tlist) + 1,
249 : pstrdup(resname),
250 : true);
251 9786 : tlist = lappend(tlist, tle);
252 : }
253 10464 : if (rc->allMarkTypes & (1 << ROW_MARK_COPY))
254 : {
255 : /* Need the whole row as a junk var */
256 678 : var = makeWholeRowVar(rt_fetch(rc->rti, range_table),
257 678 : rc->rti,
258 : 0,
259 : false);
260 678 : snprintf(resname, sizeof(resname), "wholerow%u", rc->rowmarkId);
261 678 : tle = makeTargetEntry((Expr *) var,
262 678 : list_length(tlist) + 1,
263 : pstrdup(resname),
264 : true);
265 678 : tlist = lappend(tlist, tle);
266 : }
267 :
268 : /* If parent of inheritance tree, always fetch the tableoid too. */
269 10464 : if (rc->isParent)
270 : {
271 0 : var = makeVar(rc->rti,
272 : TableOidAttributeNumber,
273 : OIDOID,
274 : -1,
275 : InvalidOid,
276 : 0);
277 0 : snprintf(resname, sizeof(resname), "tableoid%u", rc->rowmarkId);
278 0 : tle = makeTargetEntry((Expr *) var,
279 0 : list_length(tlist) + 1,
280 : pstrdup(resname),
281 : true);
282 0 : tlist = lappend(tlist, tle);
283 : }
284 : }
285 :
286 : /*
287 : * If the query has a RETURNING list, add resjunk entries for any Vars
288 : * used in RETURNING that belong to other relations. We need to do this
289 : * to make these Vars available for the RETURNING calculation. Vars that
290 : * belong to the result rel don't need to be added, because they will be
291 : * made to refer to the actual heap tuple.
292 : */
293 505632 : if (parse->returningList && list_length(parse->rtable) > 1)
294 : {
295 : List *vars;
296 : ListCell *l;
297 :
298 1516 : vars = pull_var_clause((Node *) parse->returningList,
299 : PVC_RECURSE_AGGREGATES |
300 : PVC_RECURSE_WINDOWFUNCS |
301 : PVC_INCLUDE_PLACEHOLDERS);
302 5604 : foreach(l, vars)
303 : {
304 4088 : Var *var = (Var *) lfirst(l);
305 : TargetEntry *tle;
306 :
307 4088 : if (IsA(var, Var) &&
308 4088 : var->varno == result_relation)
309 3618 : continue; /* don't need it */
310 :
311 470 : if (tlist_member((Expr *) var, tlist))
312 154 : continue; /* already got it */
313 :
314 316 : tle = makeTargetEntry((Expr *) var,
315 316 : list_length(tlist) + 1,
316 : NULL,
317 : true);
318 :
319 316 : tlist = lappend(tlist, tle);
320 : }
321 1516 : list_free(vars);
322 : }
323 :
324 505632 : root->processed_tlist = tlist;
325 :
326 505632 : if (target_relation)
327 90330 : table_close(target_relation, NoLock);
328 505632 : }
329 :
330 : /*
331 : * extract_update_targetlist_colnos
332 : * Extract a list of the target-table column numbers that
333 : * an UPDATE's targetlist wants to assign to, then renumber.
334 : *
335 : * The convention in the parser and rewriter is that the resnos in an
336 : * UPDATE's non-resjunk TLE entries are the target column numbers
337 : * to assign to. Here, we extract that info into a separate list, and
338 : * then convert the tlist to the sequential-numbering convention that's
339 : * used by all other query types.
340 : *
341 : * This is also applied to the tlist associated with INSERT ... ON CONFLICT
342 : * ... UPDATE, although not till much later in planning.
343 : */
344 : List *
345 16268 : extract_update_targetlist_colnos(List *tlist)
346 : {
347 16268 : List *update_colnos = NIL;
348 16268 : AttrNumber nextresno = 1;
349 : ListCell *lc;
350 :
351 36190 : foreach(lc, tlist)
352 : {
353 19922 : TargetEntry *tle = (TargetEntry *) lfirst(lc);
354 :
355 19922 : if (!tle->resjunk)
356 19652 : update_colnos = lappend_int(update_colnos, tle->resno);
357 19922 : tle->resno = nextresno++;
358 : }
359 16268 : return update_colnos;
360 : }
361 :
362 :
363 : /*****************************************************************************
364 : *
365 : * TARGETLIST EXPANSION
366 : *
367 : *****************************************************************************/
368 :
369 : /*
370 : * expand_insert_targetlist
371 : * Given a target list as generated by the parser and a result relation,
372 : * add targetlist entries for any missing attributes, and ensure the
373 : * non-junk attributes appear in proper field order.
374 : *
375 : * Once upon a time we also did more or less this with UPDATE targetlists,
376 : * but now this code is only applied to INSERT targetlists.
377 : */
378 : static List *
379 72020 : expand_insert_targetlist(List *tlist, Relation rel)
380 : {
381 72020 : List *new_tlist = NIL;
382 : ListCell *tlist_item;
383 : int attrno,
384 : numattrs;
385 :
386 72020 : tlist_item = list_head(tlist);
387 :
388 : /*
389 : * The rewriter should have already ensured that the TLEs are in correct
390 : * order; but we have to insert TLEs for any missing attributes.
391 : *
392 : * Scan the tuple description in the relation's relcache entry to make
393 : * sure we have all the user attributes in the right order.
394 : */
395 72020 : numattrs = RelationGetNumberOfAttributes(rel);
396 :
397 231494 : for (attrno = 1; attrno <= numattrs; attrno++)
398 : {
399 159474 : Form_pg_attribute att_tup = TupleDescAttr(rel->rd_att, attrno - 1);
400 159474 : TargetEntry *new_tle = NULL;
401 :
402 159474 : if (tlist_item != NULL)
403 : {
404 149638 : TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
405 :
406 149638 : if (!old_tle->resjunk && old_tle->resno == attrno)
407 : {
408 140684 : new_tle = old_tle;
409 140684 : tlist_item = lnext(tlist, tlist_item);
410 : }
411 : }
412 :
413 159474 : if (new_tle == NULL)
414 : {
415 : /*
416 : * Didn't find a matching tlist entry, so make one.
417 : *
418 : * INSERTs should insert NULL in this case. (We assume the
419 : * rewriter would have inserted any available non-NULL default
420 : * value.) Also, if the column isn't dropped, apply any domain
421 : * constraints that might exist --- this is to catch domain NOT
422 : * NULL.
423 : *
424 : * When generating a NULL constant for a dropped column, we label
425 : * it INT4 (any other guaranteed-to-exist datatype would do as
426 : * well). We can't label it with the dropped column's datatype
427 : * since that might not exist anymore. It does not really matter
428 : * what we claim the type is, since NULL is NULL --- its
429 : * representation is datatype-independent. This could perhaps
430 : * confuse code comparing the finished plan to the target
431 : * relation, however.
432 : */
433 18790 : Oid atttype = att_tup->atttypid;
434 18790 : Oid attcollation = att_tup->attcollation;
435 : Node *new_expr;
436 :
437 18790 : if (!att_tup->attisdropped)
438 : {
439 18168 : new_expr = (Node *) makeConst(atttype,
440 : -1,
441 : attcollation,
442 18168 : att_tup->attlen,
443 : (Datum) 0,
444 : true, /* isnull */
445 18168 : att_tup->attbyval);
446 18168 : new_expr = coerce_to_domain(new_expr,
447 : InvalidOid, -1,
448 : atttype,
449 : COERCION_IMPLICIT,
450 : COERCE_IMPLICIT_CAST,
451 : -1,
452 : false);
453 : }
454 : else
455 : {
456 : /* Insert NULL for dropped column */
457 622 : new_expr = (Node *) makeConst(INT4OID,
458 : -1,
459 : InvalidOid,
460 : sizeof(int32),
461 : (Datum) 0,
462 : true, /* isnull */
463 : true /* byval */ );
464 : }
465 :
466 18790 : new_tle = makeTargetEntry((Expr *) new_expr,
467 : attrno,
468 18790 : pstrdup(NameStr(att_tup->attname)),
469 : false);
470 : }
471 :
472 159474 : new_tlist = lappend(new_tlist, new_tle);
473 : }
474 :
475 : /*
476 : * The remaining tlist entries should be resjunk; append them all to the
477 : * end of the new tlist, making sure they have resnos higher than the last
478 : * real attribute. (Note: although the rewriter already did such
479 : * renumbering, we have to do it again here in case we added NULL entries
480 : * above.)
481 : */
482 72020 : while (tlist_item)
483 : {
484 0 : TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
485 :
486 0 : if (!old_tle->resjunk)
487 0 : elog(ERROR, "targetlist is not sorted correctly");
488 : /* Get the resno right, but don't copy unnecessarily */
489 0 : if (old_tle->resno != attrno)
490 : {
491 0 : old_tle = flatCopyTargetEntry(old_tle);
492 0 : old_tle->resno = attrno;
493 : }
494 0 : new_tlist = lappend(new_tlist, old_tle);
495 0 : attrno++;
496 0 : tlist_item = lnext(tlist, tlist_item);
497 : }
498 :
499 72020 : return new_tlist;
500 : }
501 :
502 :
503 : /*
504 : * Locate PlanRowMark for given RT index, or return NULL if none
505 : *
506 : * This probably ought to be elsewhere, but there's no very good place
507 : */
508 : PlanRowMark *
509 22296 : get_plan_rowmark(List *rowmarks, Index rtindex)
510 : {
511 : ListCell *l;
512 :
513 23624 : foreach(l, rowmarks)
514 : {
515 3594 : PlanRowMark *rc = (PlanRowMark *) lfirst(l);
516 :
517 3594 : if (rc->rti == rtindex)
518 2266 : return rc;
519 : }
520 20030 : return NULL;
521 : }
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