Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * paramassign.c
4 : * Functions for assigning PARAM_EXEC slots during planning.
5 : *
6 : * This module is responsible for managing three planner data structures:
7 : *
8 : * root->glob->paramExecTypes: records actual assignments of PARAM_EXEC slots.
9 : * The i'th list element holds the data type OID of the i'th parameter slot.
10 : * (Elements can be InvalidOid if they represent slots that are needed for
11 : * chgParam signaling, but will never hold a value at runtime.) This list is
12 : * global to the whole plan since the executor has only one PARAM_EXEC array.
13 : * Assignments are permanent for the plan: we never remove entries once added.
14 : *
15 : * root->plan_params: a list of PlannerParamItem nodes, recording Vars and
16 : * PlaceHolderVars that the root's query level needs to supply to lower-level
17 : * subqueries, along with the PARAM_EXEC number to use for each such value.
18 : * Elements are added to this list while planning a subquery, and the list
19 : * is reset to empty after completion of each subquery.
20 : *
21 : * root->curOuterParams: a list of NestLoopParam nodes, recording Vars and
22 : * PlaceHolderVars that some outer level of nestloop needs to pass down to
23 : * a lower-level plan node in its righthand side. Elements are added to this
24 : * list as createplan.c creates lower Plan nodes that need such Params, and
25 : * are removed when it creates a NestLoop Plan node that will supply those
26 : * values.
27 : *
28 : * The latter two data structures are used to prevent creating multiple
29 : * PARAM_EXEC slots (each requiring work to fill) when the same upper
30 : * SubPlan or NestLoop supplies a value that is referenced in more than
31 : * one place in its child plan nodes. However, when the same Var has to
32 : * be supplied to different subplan trees by different SubPlan or NestLoop
33 : * parent nodes, we don't recognize any commonality; a fresh plan_params or
34 : * curOuterParams entry will be made (since the old one has been removed
35 : * when we finished processing the earlier SubPlan or NestLoop) and a fresh
36 : * PARAM_EXEC number will be assigned. At one time we tried to avoid
37 : * allocating duplicate PARAM_EXEC numbers in such cases, but it's harder
38 : * than it seems to avoid bugs due to overlapping Param lifetimes, so we
39 : * don't risk that anymore. Minimizing the number of PARAM_EXEC slots
40 : * doesn't really save much executor work anyway.
41 : *
42 : *
43 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
44 : * Portions Copyright (c) 1994, Regents of the University of California
45 : *
46 : * IDENTIFICATION
47 : * src/backend/optimizer/util/paramassign.c
48 : *
49 : *-------------------------------------------------------------------------
50 : */
51 : #include "postgres.h"
52 :
53 : #include "nodes/nodeFuncs.h"
54 : #include "nodes/plannodes.h"
55 : #include "optimizer/paramassign.h"
56 : #include "optimizer/placeholder.h"
57 : #include "rewrite/rewriteManip.h"
58 :
59 :
60 : /*
61 : * Select a PARAM_EXEC number to identify the given Var as a parameter for
62 : * the current subquery. (It might already have one.)
63 : * Record the need for the Var in the proper upper-level root->plan_params.
64 : */
65 : static int
1549 tgl 66 CBC 19428 : assign_param_for_var(PlannerInfo *root, Var *var)
67 : {
68 : ListCell *ppl;
69 : PlannerParamItem *pitem;
70 : Index levelsup;
71 :
72 : /* Find the query level the Var belongs to */
73 39573 : for (levelsup = var->varlevelsup; levelsup > 0; levelsup--)
74 20145 : root = root->parent_root;
75 :
76 : /* If there's already a matching PlannerParamItem there, just use it */
77 29060 : foreach(ppl, root->plan_params)
78 : {
79 12683 : pitem = (PlannerParamItem *) lfirst(ppl);
80 12683 : if (IsA(pitem->item, Var))
81 : {
82 12683 : Var *pvar = (Var *) pitem->item;
83 :
84 : /*
85 : * This comparison must match _equalVar(), except for ignoring
86 : * varlevelsup. Note that _equalVar() ignores varnosyn,
87 : * varattnosyn, and location, so this does too.
88 : */
89 12683 : if (pvar->varno == var->varno &&
90 11719 : pvar->varattno == var->varattno &&
91 3051 : pvar->vartype == var->vartype &&
92 3051 : pvar->vartypmod == var->vartypmod &&
1186 93 3051 : pvar->varcollid == var->varcollid)
1549 94 3051 : return pitem->paramId;
95 : }
96 : }
97 :
98 : /* Nope, so make a new one */
99 16377 : var = copyObject(var);
100 16377 : var->varlevelsup = 0;
101 :
102 16377 : pitem = makeNode(PlannerParamItem);
103 16377 : pitem->item = (Node *) var;
104 16377 : pitem->paramId = list_length(root->glob->paramExecTypes);
105 16377 : root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
106 : var->vartype);
107 :
108 16377 : root->plan_params = lappend(root->plan_params, pitem);
109 :
110 16377 : return pitem->paramId;
111 : }
112 :
113 : /*
114 : * Generate a Param node to replace the given Var,
115 : * which is expected to have varlevelsup > 0 (ie, it is not local).
116 : * Record the need for the Var in the proper upper-level root->plan_params.
117 : */
118 : Param *
119 19428 : replace_outer_var(PlannerInfo *root, Var *var)
120 : {
121 : Param *retval;
122 : int i;
123 :
124 19428 : Assert(var->varlevelsup > 0 && var->varlevelsup < root->query_level);
125 :
126 : /* Find the Var in the appropriate plan_params, or add it if not present */
127 19428 : i = assign_param_for_var(root, var);
128 :
129 19428 : retval = makeNode(Param);
130 19428 : retval->paramkind = PARAM_EXEC;
131 19428 : retval->paramid = i;
132 19428 : retval->paramtype = var->vartype;
133 19428 : retval->paramtypmod = var->vartypmod;
134 19428 : retval->paramcollid = var->varcollid;
135 19428 : retval->location = var->location;
136 :
137 19428 : return retval;
138 : }
139 :
140 : /*
141 : * Select a PARAM_EXEC number to identify the given PlaceHolderVar as a
142 : * parameter for the current subquery. (It might already have one.)
143 : * Record the need for the PHV in the proper upper-level root->plan_params.
144 : *
145 : * This is just like assign_param_for_var, except for PlaceHolderVars.
146 : */
147 : static int
148 21 : assign_param_for_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
149 : {
150 : ListCell *ppl;
151 : PlannerParamItem *pitem;
152 : Index levelsup;
153 :
154 : /* Find the query level the PHV belongs to */
155 42 : for (levelsup = phv->phlevelsup; levelsup > 0; levelsup--)
156 21 : root = root->parent_root;
157 :
158 : /* If there's already a matching PlannerParamItem there, just use it */
159 51 : foreach(ppl, root->plan_params)
160 : {
161 30 : pitem = (PlannerParamItem *) lfirst(ppl);
162 30 : if (IsA(pitem->item, PlaceHolderVar))
163 : {
1549 tgl 164 UBC 0 : PlaceHolderVar *pphv = (PlaceHolderVar *) pitem->item;
165 :
166 : /* We assume comparing the PHIDs is sufficient */
167 0 : if (pphv->phid == phv->phid)
168 0 : return pitem->paramId;
169 : }
170 : }
171 :
172 : /* Nope, so make a new one */
1549 tgl 173 CBC 21 : phv = copyObject(phv);
174 21 : IncrementVarSublevelsUp((Node *) phv, -((int) phv->phlevelsup), 0);
175 21 : Assert(phv->phlevelsup == 0);
176 :
177 21 : pitem = makeNode(PlannerParamItem);
178 21 : pitem->item = (Node *) phv;
179 21 : pitem->paramId = list_length(root->glob->paramExecTypes);
180 21 : root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
181 21 : exprType((Node *) phv->phexpr));
182 :
183 21 : root->plan_params = lappend(root->plan_params, pitem);
184 :
185 21 : return pitem->paramId;
186 : }
187 :
188 : /*
189 : * Generate a Param node to replace the given PlaceHolderVar,
190 : * which is expected to have phlevelsup > 0 (ie, it is not local).
191 : * Record the need for the PHV in the proper upper-level root->plan_params.
192 : *
193 : * This is just like replace_outer_var, except for PlaceHolderVars.
194 : */
195 : Param *
196 21 : replace_outer_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
197 : {
198 : Param *retval;
199 : int i;
200 :
201 21 : Assert(phv->phlevelsup > 0 && phv->phlevelsup < root->query_level);
202 :
203 : /* Find the PHV in the appropriate plan_params, or add it if not present */
204 21 : i = assign_param_for_placeholdervar(root, phv);
205 :
206 21 : retval = makeNode(Param);
207 21 : retval->paramkind = PARAM_EXEC;
208 21 : retval->paramid = i;
209 21 : retval->paramtype = exprType((Node *) phv->phexpr);
210 21 : retval->paramtypmod = exprTypmod((Node *) phv->phexpr);
211 21 : retval->paramcollid = exprCollation((Node *) phv->phexpr);
212 21 : retval->location = -1;
213 :
214 21 : return retval;
215 : }
216 :
217 : /*
218 : * Generate a Param node to replace the given Aggref
219 : * which is expected to have agglevelsup > 0 (ie, it is not local).
220 : * Record the need for the Aggref in the proper upper-level root->plan_params.
221 : */
222 : Param *
223 26 : replace_outer_agg(PlannerInfo *root, Aggref *agg)
224 : {
225 : Param *retval;
226 : PlannerParamItem *pitem;
227 : Index levelsup;
228 :
229 26 : Assert(agg->agglevelsup > 0 && agg->agglevelsup < root->query_level);
230 :
231 : /* Find the query level the Aggref belongs to */
232 52 : for (levelsup = agg->agglevelsup; levelsup > 0; levelsup--)
233 26 : root = root->parent_root;
234 :
235 : /*
236 : * It does not seem worthwhile to try to de-duplicate references to outer
237 : * aggs. Just make a new slot every time.
238 : */
239 26 : agg = copyObject(agg);
240 26 : IncrementVarSublevelsUp((Node *) agg, -((int) agg->agglevelsup), 0);
241 26 : Assert(agg->agglevelsup == 0);
242 :
243 26 : pitem = makeNode(PlannerParamItem);
244 26 : pitem->item = (Node *) agg;
245 26 : pitem->paramId = list_length(root->glob->paramExecTypes);
246 26 : root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
247 : agg->aggtype);
248 :
249 26 : root->plan_params = lappend(root->plan_params, pitem);
250 :
251 26 : retval = makeNode(Param);
252 26 : retval->paramkind = PARAM_EXEC;
253 26 : retval->paramid = pitem->paramId;
254 26 : retval->paramtype = agg->aggtype;
255 26 : retval->paramtypmod = -1;
256 26 : retval->paramcollid = agg->aggcollid;
257 26 : retval->location = agg->location;
258 :
259 26 : return retval;
260 : }
261 :
262 : /*
263 : * Generate a Param node to replace the given GroupingFunc expression which is
264 : * expected to have agglevelsup > 0 (ie, it is not local).
265 : * Record the need for the GroupingFunc in the proper upper-level
266 : * root->plan_params.
267 : */
268 : Param *
269 32 : replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp)
270 : {
271 : Param *retval;
272 : PlannerParamItem *pitem;
273 : Index levelsup;
274 32 : Oid ptype = exprType((Node *) grp);
275 :
276 32 : Assert(grp->agglevelsup > 0 && grp->agglevelsup < root->query_level);
277 :
278 : /* Find the query level the GroupingFunc belongs to */
279 68 : for (levelsup = grp->agglevelsup; levelsup > 0; levelsup--)
280 36 : root = root->parent_root;
281 :
282 : /*
283 : * It does not seem worthwhile to try to de-duplicate references to outer
284 : * aggs. Just make a new slot every time.
285 : */
286 32 : grp = copyObject(grp);
287 32 : IncrementVarSublevelsUp((Node *) grp, -((int) grp->agglevelsup), 0);
288 32 : Assert(grp->agglevelsup == 0);
289 :
290 32 : pitem = makeNode(PlannerParamItem);
291 32 : pitem->item = (Node *) grp;
292 32 : pitem->paramId = list_length(root->glob->paramExecTypes);
293 32 : root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
294 : ptype);
295 :
296 32 : root->plan_params = lappend(root->plan_params, pitem);
297 :
298 32 : retval = makeNode(Param);
299 32 : retval->paramkind = PARAM_EXEC;
300 32 : retval->paramid = pitem->paramId;
301 32 : retval->paramtype = ptype;
302 32 : retval->paramtypmod = -1;
303 32 : retval->paramcollid = InvalidOid;
304 32 : retval->location = grp->location;
305 :
306 32 : return retval;
307 : }
308 :
309 : /*
310 : * Generate a Param node to replace the given Var,
311 : * which is expected to come from some upper NestLoop plan node.
312 : * Record the need for the Var in root->curOuterParams.
313 : */
314 : Param *
315 33369 : replace_nestloop_param_var(PlannerInfo *root, Var *var)
316 : {
317 : Param *param;
318 : NestLoopParam *nlp;
319 : ListCell *lc;
320 :
321 : /* Is this Var already listed in root->curOuterParams? */
322 35997 : foreach(lc, root->curOuterParams)
323 : {
324 18081 : nlp = (NestLoopParam *) lfirst(lc);
325 18081 : if (equal(var, nlp->paramval))
326 : {
327 : /* Yes, so just make a Param referencing this NLP's slot */
328 15453 : param = makeNode(Param);
329 15453 : param->paramkind = PARAM_EXEC;
330 15453 : param->paramid = nlp->paramno;
331 15453 : param->paramtype = var->vartype;
332 15453 : param->paramtypmod = var->vartypmod;
333 15453 : param->paramcollid = var->varcollid;
334 15453 : param->location = var->location;
335 15453 : return param;
336 : }
337 : }
338 :
339 : /* No, so assign a PARAM_EXEC slot for a new NLP */
340 17916 : param = generate_new_exec_param(root,
341 : var->vartype,
342 : var->vartypmod,
343 : var->varcollid);
344 17916 : param->location = var->location;
345 :
346 : /* Add it to the list of required NLPs */
347 17916 : nlp = makeNode(NestLoopParam);
348 17916 : nlp->paramno = param->paramid;
349 17916 : nlp->paramval = copyObject(var);
350 17916 : root->curOuterParams = lappend(root->curOuterParams, nlp);
351 :
352 : /* And return the replacement Param */
353 17916 : return param;
354 : }
355 :
356 : /*
357 : * Generate a Param node to replace the given PlaceHolderVar,
358 : * which is expected to come from some upper NestLoop plan node.
359 : * Record the need for the PHV in root->curOuterParams.
360 : *
361 : * This is just like replace_nestloop_param_var, except for PlaceHolderVars.
362 : */
363 : Param *
364 117 : replace_nestloop_param_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
365 : {
366 : Param *param;
367 : NestLoopParam *nlp;
368 : ListCell *lc;
369 :
370 : /* Is this PHV already listed in root->curOuterParams? */
371 156 : foreach(lc, root->curOuterParams)
372 : {
373 90 : nlp = (NestLoopParam *) lfirst(lc);
374 90 : if (equal(phv, nlp->paramval))
375 : {
376 : /* Yes, so just make a Param referencing this NLP's slot */
377 51 : param = makeNode(Param);
378 51 : param->paramkind = PARAM_EXEC;
379 51 : param->paramid = nlp->paramno;
380 51 : param->paramtype = exprType((Node *) phv->phexpr);
381 51 : param->paramtypmod = exprTypmod((Node *) phv->phexpr);
382 51 : param->paramcollid = exprCollation((Node *) phv->phexpr);
383 51 : param->location = -1;
384 51 : return param;
385 : }
386 : }
387 :
388 : /* No, so assign a PARAM_EXEC slot for a new NLP */
389 66 : param = generate_new_exec_param(root,
390 66 : exprType((Node *) phv->phexpr),
391 66 : exprTypmod((Node *) phv->phexpr),
392 66 : exprCollation((Node *) phv->phexpr));
393 :
394 : /* Add it to the list of required NLPs */
395 66 : nlp = makeNode(NestLoopParam);
396 66 : nlp->paramno = param->paramid;
397 66 : nlp->paramval = (Var *) copyObject(phv);
398 66 : root->curOuterParams = lappend(root->curOuterParams, nlp);
399 :
400 : /* And return the replacement Param */
401 66 : return param;
402 : }
403 :
404 : /*
405 : * process_subquery_nestloop_params
406 : * Handle params of a parameterized subquery that need to be fed
407 : * from an outer nestloop.
408 : *
409 : * Currently, that would be *all* params that a subquery in FROM has demanded
410 : * from the current query level, since they must be LATERAL references.
411 : *
412 : * subplan_params is a list of PlannerParamItems that we intend to pass to
413 : * a subquery-in-FROM. (This was constructed in root->plan_params while
414 : * planning the subquery, but isn't there anymore when this is called.)
415 : *
416 : * The subplan's references to the outer variables are already represented
417 : * as PARAM_EXEC Params, since that conversion was done by the routines above
418 : * while planning the subquery. So we need not modify the subplan or the
419 : * PlannerParamItems here. What we do need to do is add entries to
420 : * root->curOuterParams to signal the parent nestloop plan node that it must
421 : * provide these values. This differs from replace_nestloop_param_var in
422 : * that the PARAM_EXEC slots to use have already been determined.
423 : *
424 : * Note that we also use root->curOuterRels as an implicit parameter for
425 : * sanity checks.
426 : */
427 : void
428 191 : process_subquery_nestloop_params(PlannerInfo *root, List *subplan_params)
429 : {
430 : ListCell *lc;
431 :
432 430 : foreach(lc, subplan_params)
433 : {
629 peter 434 239 : PlannerParamItem *pitem = lfirst_node(PlannerParamItem, lc);
435 :
1549 tgl 436 239 : if (IsA(pitem->item, Var))
437 : {
438 224 : Var *var = (Var *) pitem->item;
439 : NestLoopParam *nlp;
440 : ListCell *lc2;
441 :
442 : /* If not from a nestloop outer rel, complain */
443 224 : if (!bms_is_member(var->varno, root->curOuterRels))
1549 tgl 444 UBC 0 : elog(ERROR, "non-LATERAL parameter required by subquery");
445 :
446 : /* Is this param already listed in root->curOuterParams? */
186 drowley 447 GNC 328 : foreach(lc2, root->curOuterParams)
448 : {
449 104 : nlp = (NestLoopParam *) lfirst(lc2);
1549 tgl 450 CBC 104 : if (nlp->paramno == pitem->paramId)
451 : {
1549 tgl 452 UBC 0 : Assert(equal(var, nlp->paramval));
453 : /* Present, so nothing to do */
454 0 : break;
455 : }
456 : }
186 drowley 457 GNC 224 : if (lc2 == NULL)
458 : {
459 : /* No, so add it */
1549 tgl 460 CBC 224 : nlp = makeNode(NestLoopParam);
461 224 : nlp->paramno = pitem->paramId;
462 224 : nlp->paramval = copyObject(var);
463 224 : root->curOuterParams = lappend(root->curOuterParams, nlp);
464 : }
465 : }
466 15 : else if (IsA(pitem->item, PlaceHolderVar))
467 : {
468 15 : PlaceHolderVar *phv = (PlaceHolderVar *) pitem->item;
469 : NestLoopParam *nlp;
470 : ListCell *lc2;
471 :
472 : /* If not from a nestloop outer rel, complain */
235 tgl 473 GNC 15 : if (!bms_is_subset(find_placeholder_info(root, phv)->ph_eval_at,
1549 tgl 474 CBC 15 : root->curOuterRels))
1549 tgl 475 UBC 0 : elog(ERROR, "non-LATERAL parameter required by subquery");
476 :
477 : /* Is this param already listed in root->curOuterParams? */
186 drowley 478 GNC 45 : foreach(lc2, root->curOuterParams)
479 : {
480 30 : nlp = (NestLoopParam *) lfirst(lc2);
1549 tgl 481 CBC 30 : if (nlp->paramno == pitem->paramId)
482 : {
1549 tgl 483 UBC 0 : Assert(equal(phv, nlp->paramval));
484 : /* Present, so nothing to do */
485 0 : break;
486 : }
487 : }
186 drowley 488 GNC 15 : if (lc2 == NULL)
489 : {
490 : /* No, so add it */
1549 tgl 491 CBC 15 : nlp = makeNode(NestLoopParam);
492 15 : nlp->paramno = pitem->paramId;
493 15 : nlp->paramval = (Var *) copyObject(phv);
494 15 : root->curOuterParams = lappend(root->curOuterParams, nlp);
495 : }
496 : }
497 : else
1549 tgl 498 UBC 0 : elog(ERROR, "unexpected type of subquery parameter");
499 : }
1549 tgl 500 CBC 191 : }
501 :
502 : /*
503 : * Identify any NestLoopParams that should be supplied by a NestLoop plan
504 : * node with the specified lefthand rels. Remove them from the active
505 : * root->curOuterParams list and return them as the result list.
506 : */
507 : List *
508 32419 : identify_current_nestloop_params(PlannerInfo *root, Relids leftrelids)
509 : {
510 : List *result;
511 : ListCell *cell;
512 :
513 32419 : result = NIL;
1364 514 51079 : foreach(cell, root->curOuterParams)
515 : {
1549 516 18660 : NestLoopParam *nlp = (NestLoopParam *) lfirst(cell);
517 :
518 : /*
519 : * We are looking for Vars and PHVs that can be supplied by the
520 : * lefthand rels.
1549 tgl 521 ECB : */
1549 tgl 522 CBC 37239 : if (IsA(nlp->paramval, Var) &&
1549 tgl 523 GIC 18579 : bms_is_member(nlp->paramval->varno, leftrelids))
1549 tgl 524 ECB : {
1364 tgl 525 GIC 18140 : root->curOuterParams = foreach_delete_current(root->curOuterParams,
1364 tgl 526 ECB : cell);
1549 tgl 527 GIC 18140 : result = lappend(result, nlp);
1549 tgl 528 ECB : }
1549 tgl 529 CBC 601 : else if (IsA(nlp->paramval, PlaceHolderVar) &&
1549 tgl 530 GIC 162 : bms_is_subset(find_placeholder_info(root,
235 tgl 531 GNC 81 : (PlaceHolderVar *) nlp->paramval)->ph_eval_at,
1549 tgl 532 ECB : leftrelids))
533 : {
1364 tgl 534 GIC 81 : root->curOuterParams = foreach_delete_current(root->curOuterParams,
1364 tgl 535 ECB : cell);
1549 tgl 536 GIC 81 : result = lappend(result, nlp);
537 : }
538 : }
539 32419 : return result;
540 : }
541 :
542 : /*
543 : * Generate a new Param node that will not conflict with any other.
544 : *
545 : * This is used to create Params representing subplan outputs or
546 : * NestLoop parameters.
547 : *
548 : * We don't need to build a PlannerParamItem for such a Param, but we do
1549 tgl 549 ECB : * need to make sure we record the type in paramExecTypes (otherwise,
550 : * there won't be a slot allocated for it).
551 : */
552 : Param *
1549 tgl 553 GIC 26823 : generate_new_exec_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod,
1549 tgl 554 ECB : Oid paramcollation)
555 : {
556 : Param *retval;
557 :
1549 tgl 558 GIC 26823 : retval = makeNode(Param);
1549 tgl 559 CBC 26823 : retval->paramkind = PARAM_EXEC;
560 26823 : retval->paramid = list_length(root->glob->paramExecTypes);
561 26823 : root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
1549 tgl 562 ECB : paramtype);
1549 tgl 563 GIC 26823 : retval->paramtype = paramtype;
1549 tgl 564 CBC 26823 : retval->paramtypmod = paramtypmod;
1549 tgl 565 GIC 26823 : retval->paramcollid = paramcollation;
566 26823 : retval->location = -1;
567 :
568 26823 : return retval;
569 : }
570 :
571 : /*
572 : * Assign a (nonnegative) PARAM_EXEC ID for a special parameter (one that
573 : * is not actually used to carry a value at runtime). Such parameters are
574 : * used for special runtime signaling purposes, such as connecting a
575 : * recursive union node to its worktable scan node or forcing plan
1549 tgl 576 ECB : * re-evaluation within the EvalPlanQual mechanism. No actual Param node
577 : * exists with this ID, however.
578 : */
579 : int
1549 tgl 580 CBC 57657 : assign_special_exec_param(PlannerInfo *root)
581 : {
582 57657 : int paramId = list_length(root->glob->paramExecTypes);
583 :
1549 tgl 584 GIC 57657 : root->glob->paramExecTypes = lappend_oid(root->glob->paramExecTypes,
585 : InvalidOid);
586 57657 : return paramId;
587 : }
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