Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeFunctionscan.c
4 : * Support routines for scanning RangeFunctions (functions in rangetable).
5 : *
6 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/executor/nodeFunctionscan.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : /*
16 : * INTERFACE ROUTINES
17 : * ExecFunctionScan scans a function.
18 : * ExecFunctionNext retrieve next tuple in sequential order.
19 : * ExecInitFunctionScan creates and initializes a functionscan node.
20 : * ExecEndFunctionScan releases any storage allocated.
21 : * ExecReScanFunctionScan rescans the function
22 : */
23 : #include "postgres.h"
24 :
25 : #include "catalog/pg_type.h"
26 : #include "executor/nodeFunctionscan.h"
27 : #include "funcapi.h"
28 : #include "nodes/nodeFuncs.h"
29 : #include "utils/memutils.h"
30 : #include "utils/tuplestore.h"
31 :
32 :
33 : /*
34 : * Runtime data for each function being scanned.
35 : */
36 : typedef struct FunctionScanPerFuncState
37 : {
38 : SetExprState *setexpr; /* state of the expression being evaluated */
39 : TupleDesc tupdesc; /* desc of the function result type */
40 : int colcount; /* expected number of result columns */
41 : Tuplestorestate *tstore; /* holds the function result set */
42 : int64 rowcount; /* # of rows in result set, -1 if not known */
43 : TupleTableSlot *func_slot; /* function result slot (or NULL) */
44 : } FunctionScanPerFuncState;
45 :
46 : static TupleTableSlot *FunctionNext(FunctionScanState *node);
47 :
48 :
49 : /* ----------------------------------------------------------------
50 : * Scan Support
51 : * ----------------------------------------------------------------
52 : */
53 : /* ----------------------------------------------------------------
54 : * FunctionNext
55 : *
56 : * This is a workhorse for ExecFunctionScan
57 : * ----------------------------------------------------------------
58 : */
59 : static TupleTableSlot *
60 10645298 : FunctionNext(FunctionScanState *node)
61 : {
62 : EState *estate;
63 : ScanDirection direction;
64 : TupleTableSlot *scanslot;
65 : bool alldone;
66 : int64 oldpos;
67 : int funcno;
68 : int att;
69 :
70 : /*
71 : * get information from the estate and scan state
72 : */
73 10645298 : estate = node->ss.ps.state;
74 10645298 : direction = estate->es_direction;
75 10645298 : scanslot = node->ss.ss_ScanTupleSlot;
76 :
77 10645298 : if (node->simple)
78 : {
79 : /*
80 : * Fast path for the trivial case: the function return type and scan
81 : * result type are the same, so we fetch the function result straight
82 : * into the scan result slot. No need to update ordinality or
83 : * rowcounts either.
84 : */
85 10630729 : Tuplestorestate *tstore = node->funcstates[0].tstore;
86 :
87 : /*
88 : * If first time through, read all tuples from function and put them
89 : * in a tuplestore. Subsequent calls just fetch tuples from
90 : * tuplestore.
91 : */
92 10630729 : if (tstore == NULL)
93 : {
94 96871 : node->funcstates[0].tstore = tstore =
95 100251 : ExecMakeTableFunctionResult(node->funcstates[0].setexpr,
96 : node->ss.ps.ps_ExprContext,
97 : node->argcontext,
98 100251 : node->funcstates[0].tupdesc,
99 100251 : node->eflags & EXEC_FLAG_BACKWARD);
100 :
101 : /*
102 : * paranoia - cope if the function, which may have constructed the
103 : * tuplestore itself, didn't leave it pointing at the start. This
104 : * call is fast, so the overhead shouldn't be an issue.
105 : */
106 96871 : tuplestore_rescan(tstore);
107 : }
108 :
109 : /*
110 : * Get the next tuple from tuplestore.
111 : */
112 10627349 : (void) tuplestore_gettupleslot(tstore,
113 : ScanDirectionIsForward(direction),
114 : false,
115 : scanslot);
116 10627349 : return scanslot;
117 : }
118 :
119 : /*
120 : * Increment or decrement ordinal counter before checking for end-of-data,
121 : * so that we can move off either end of the result by 1 (and no more than
122 : * 1) without losing correct count. See PortalRunSelect for why we can
123 : * assume that we won't be called repeatedly in the end-of-data state.
124 : */
125 14569 : oldpos = node->ordinal;
126 14569 : if (ScanDirectionIsForward(direction))
127 14529 : node->ordinal++;
128 : else
129 40 : node->ordinal--;
130 :
131 : /*
132 : * Main loop over functions.
133 : *
134 : * We fetch the function results into func_slots (which match the function
135 : * return types), and then copy the values to scanslot (which matches the
136 : * scan result type), setting the ordinal column (if any) as well.
137 : */
138 14569 : ExecClearTuple(scanslot);
139 14569 : att = 0;
140 14569 : alldone = true;
141 34714 : for (funcno = 0; funcno < node->nfuncs; funcno++)
142 : {
143 20145 : FunctionScanPerFuncState *fs = &node->funcstates[funcno];
144 : int i;
145 :
146 : /*
147 : * If first time through, read all tuples from function and put them
148 : * in a tuplestore. Subsequent calls just fetch tuples from
149 : * tuplestore.
150 : */
151 20145 : if (fs->tstore == NULL)
152 : {
153 1514 : fs->tstore =
154 1514 : ExecMakeTableFunctionResult(fs->setexpr,
155 : node->ss.ps.ps_ExprContext,
156 : node->argcontext,
157 : fs->tupdesc,
158 1514 : node->eflags & EXEC_FLAG_BACKWARD);
159 :
160 : /*
161 : * paranoia - cope if the function, which may have constructed the
162 : * tuplestore itself, didn't leave it pointing at the start. This
163 : * call is fast, so the overhead shouldn't be an issue.
164 : */
165 1514 : tuplestore_rescan(fs->tstore);
166 : }
167 :
168 : /*
169 : * Get the next tuple from tuplestore.
170 : *
171 : * If we have a rowcount for the function, and we know the previous
172 : * read position was out of bounds, don't try the read. This allows
173 : * backward scan to work when there are mixed row counts present.
174 : */
175 20145 : if (fs->rowcount != -1 && fs->rowcount < oldpos)
176 50 : ExecClearTuple(fs->func_slot);
177 : else
178 20095 : (void) tuplestore_gettupleslot(fs->tstore,
179 : ScanDirectionIsForward(direction),
180 : false,
181 : fs->func_slot);
182 :
183 20145 : if (TupIsNull(fs->func_slot))
184 : {
185 : /*
186 : * If we ran out of data for this function in the forward
187 : * direction then we now know how many rows it returned. We need
188 : * to know this in order to handle backwards scans. The row count
189 : * we store is actually 1+ the actual number, because we have to
190 : * position the tuplestore 1 off its end sometimes.
191 : */
192 1733 : if (ScanDirectionIsForward(direction) && fs->rowcount == -1)
193 1482 : fs->rowcount = node->ordinal;
194 :
195 : /*
196 : * populate the result cols with nulls
197 : */
198 4124 : for (i = 0; i < fs->colcount; i++)
199 : {
200 2391 : scanslot->tts_values[att] = (Datum) 0;
201 2391 : scanslot->tts_isnull[att] = true;
202 2391 : att++;
203 : }
204 : }
205 : else
206 : {
207 : /*
208 : * we have a result, so just copy it to the result cols.
209 : */
210 18412 : slot_getallattrs(fs->func_slot);
211 :
212 45922 : for (i = 0; i < fs->colcount; i++)
213 : {
214 27510 : scanslot->tts_values[att] = fs->func_slot->tts_values[i];
215 27510 : scanslot->tts_isnull[att] = fs->func_slot->tts_isnull[i];
216 27510 : att++;
217 : }
218 :
219 : /*
220 : * We're not done until every function result is exhausted; we pad
221 : * the shorter results with nulls until then.
222 : */
223 18412 : alldone = false;
224 : }
225 : }
226 :
227 : /*
228 : * ordinal col is always last, per spec.
229 : */
230 14569 : if (node->ordinality)
231 : {
232 11932 : scanslot->tts_values[att] = Int64GetDatumFast(node->ordinal);
233 11932 : scanslot->tts_isnull[att] = false;
234 : }
235 :
236 : /*
237 : * If alldone, we just return the previously-cleared scanslot. Otherwise,
238 : * finish creating the virtual tuple.
239 : */
240 14569 : if (!alldone)
241 13260 : ExecStoreVirtualTuple(scanslot);
242 :
243 14569 : return scanslot;
244 : }
245 :
246 : /*
247 : * FunctionRecheck -- access method routine to recheck a tuple in EvalPlanQual
248 : */
249 : static bool
250 0 : FunctionRecheck(FunctionScanState *node, TupleTableSlot *slot)
251 : {
252 : /* nothing to check */
253 0 : return true;
254 : }
255 :
256 : /* ----------------------------------------------------------------
257 : * ExecFunctionScan(node)
258 : *
259 : * Scans the function sequentially and returns the next qualifying
260 : * tuple.
261 : * We call the ExecScan() routine and pass it the appropriate
262 : * access method functions.
263 : * ----------------------------------------------------------------
264 : */
265 : static TupleTableSlot *
266 9466263 : ExecFunctionScan(PlanState *pstate)
267 : {
268 9466263 : FunctionScanState *node = castNode(FunctionScanState, pstate);
269 :
270 9466263 : return ExecScan(&node->ss,
271 : (ExecScanAccessMtd) FunctionNext,
272 : (ExecScanRecheckMtd) FunctionRecheck);
273 : }
274 :
275 : /* ----------------------------------------------------------------
276 : * ExecInitFunctionScan
277 : * ----------------------------------------------------------------
278 : */
279 : FunctionScanState *
280 44374 : ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
281 : {
282 : FunctionScanState *scanstate;
283 44374 : int nfuncs = list_length(node->functions);
284 : TupleDesc scan_tupdesc;
285 : int i,
286 : natts;
287 : ListCell *lc;
288 :
289 : /* check for unsupported flags */
290 : Assert(!(eflags & EXEC_FLAG_MARK));
291 :
292 : /*
293 : * FunctionScan should not have any children.
294 : */
295 : Assert(outerPlan(node) == NULL);
296 : Assert(innerPlan(node) == NULL);
297 :
298 : /*
299 : * create new ScanState for node
300 : */
301 44374 : scanstate = makeNode(FunctionScanState);
302 44374 : scanstate->ss.ps.plan = (Plan *) node;
303 44374 : scanstate->ss.ps.state = estate;
304 44374 : scanstate->ss.ps.ExecProcNode = ExecFunctionScan;
305 44374 : scanstate->eflags = eflags;
306 :
307 : /*
308 : * are we adding an ordinality column?
309 : */
310 44374 : scanstate->ordinality = node->funcordinality;
311 :
312 44374 : scanstate->nfuncs = nfuncs;
313 44374 : if (nfuncs == 1 && !node->funcordinality)
314 43412 : scanstate->simple = true;
315 : else
316 962 : scanstate->simple = false;
317 :
318 : /*
319 : * Ordinal 0 represents the "before the first row" position.
320 : *
321 : * We need to track ordinal position even when not adding an ordinality
322 : * column to the result, in order to handle backwards scanning properly
323 : * with multiple functions with different result sizes. (We can't position
324 : * any individual function's tuplestore any more than 1 place beyond its
325 : * end, so when scanning backwards, we need to know when to start
326 : * including the function in the scan again.)
327 : */
328 44374 : scanstate->ordinal = 0;
329 :
330 : /*
331 : * Miscellaneous initialization
332 : *
333 : * create expression context for node
334 : */
335 44374 : ExecAssignExprContext(estate, &scanstate->ss.ps);
336 :
337 44374 : scanstate->funcstates = palloc_array(FunctionScanPerFuncState, nfuncs);
338 :
339 44374 : natts = 0;
340 44374 : i = 0;
341 88949 : foreach(lc, node->functions)
342 : {
343 44579 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
344 44579 : Node *funcexpr = rtfunc->funcexpr;
345 44579 : int colcount = rtfunc->funccolcount;
346 44579 : FunctionScanPerFuncState *fs = &scanstate->funcstates[i];
347 : TupleDesc tupdesc;
348 :
349 44575 : fs->setexpr =
350 44579 : ExecInitTableFunctionResult((Expr *) funcexpr,
351 : scanstate->ss.ps.ps_ExprContext,
352 : &scanstate->ss.ps);
353 :
354 : /*
355 : * Don't allocate the tuplestores; the actual calls to the functions
356 : * do that. NULL means that we have not called the function yet (or
357 : * need to call it again after a rescan).
358 : */
359 44575 : fs->tstore = NULL;
360 44575 : fs->rowcount = -1;
361 :
362 : /*
363 : * Now build a tupdesc showing the result type we expect from the
364 : * function. If we have a coldeflist then that takes priority (note
365 : * the parser enforces that there is one if the function's nominal
366 : * output type is RECORD). Otherwise use get_expr_result_type.
367 : *
368 : * Note that if the function returns a named composite type, that may
369 : * now contain more or different columns than it did when the plan was
370 : * made. For both that and the RECORD case, we need to check tuple
371 : * compatibility. ExecMakeTableFunctionResult handles some of this,
372 : * and CheckVarSlotCompatibility provides a backstop.
373 : */
374 44575 : if (rtfunc->funccolnames != NIL)
375 : {
376 936 : tupdesc = BuildDescFromLists(rtfunc->funccolnames,
377 468 : rtfunc->funccoltypes,
378 468 : rtfunc->funccoltypmods,
379 468 : rtfunc->funccolcollations);
380 :
381 : /*
382 : * For RECORD results, make sure a typmod has been assigned. (The
383 : * function should do this for itself, but let's cover things in
384 : * case it doesn't.)
385 : */
386 468 : BlessTupleDesc(tupdesc);
387 : }
388 : else
389 : {
390 : TypeFuncClass functypclass;
391 : Oid funcrettype;
392 :
393 44107 : functypclass = get_expr_result_type(funcexpr,
394 : &funcrettype,
395 : &tupdesc);
396 :
397 44107 : if (functypclass == TYPEFUNC_COMPOSITE ||
398 : functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
399 : {
400 : /* Composite data type, e.g. a table's row type */
401 : Assert(tupdesc);
402 : /* Must copy it out of typcache for safety */
403 24233 : tupdesc = CreateTupleDescCopy(tupdesc);
404 : }
405 19874 : else if (functypclass == TYPEFUNC_SCALAR)
406 : {
407 : /* Base data type, i.e. scalar */
408 19874 : tupdesc = CreateTemplateTupleDesc(1);
409 19874 : TupleDescInitEntry(tupdesc,
410 : (AttrNumber) 1,
411 : NULL, /* don't care about the name here */
412 : funcrettype,
413 : -1,
414 : 0);
415 19874 : TupleDescInitEntryCollation(tupdesc,
416 : (AttrNumber) 1,
417 : exprCollation(funcexpr));
418 19874 : TupleDescFinalize(tupdesc);
419 : }
420 : else
421 : {
422 : /* crummy error message, but parser should have caught this */
423 0 : elog(ERROR, "function in FROM has unsupported return type");
424 : }
425 : }
426 :
427 44575 : fs->tupdesc = tupdesc;
428 44575 : fs->colcount = colcount;
429 :
430 : /*
431 : * We only need separate slots for the function results if we are
432 : * doing ordinality or multiple functions; otherwise, we'll fetch
433 : * function results directly into the scan slot.
434 : */
435 44575 : if (!scanstate->simple)
436 : {
437 1167 : fs->func_slot = ExecInitExtraTupleSlot(estate, fs->tupdesc,
438 : &TTSOpsMinimalTuple);
439 : }
440 : else
441 43408 : fs->func_slot = NULL;
442 :
443 44575 : natts += colcount;
444 44575 : i++;
445 : }
446 :
447 : /*
448 : * Create the combined TupleDesc
449 : *
450 : * If there is just one function without ordinality, the scan result
451 : * tupdesc is the same as the function result tupdesc --- except that we
452 : * may stuff new names into it below, so drop any rowtype label.
453 : */
454 44370 : if (scanstate->simple)
455 : {
456 43408 : scan_tupdesc = CreateTupleDescCopy(scanstate->funcstates[0].tupdesc);
457 43408 : scan_tupdesc->tdtypeid = RECORDOID;
458 43408 : scan_tupdesc->tdtypmod = -1;
459 : }
460 : else
461 : {
462 962 : AttrNumber attno = 0;
463 :
464 962 : if (node->funcordinality)
465 915 : natts++;
466 :
467 962 : scan_tupdesc = CreateTemplateTupleDesc(natts);
468 :
469 2129 : for (i = 0; i < nfuncs; i++)
470 : {
471 1167 : TupleDesc tupdesc = scanstate->funcstates[i].tupdesc;
472 1167 : int colcount = scanstate->funcstates[i].colcount;
473 : int j;
474 :
475 2760 : for (j = 1; j <= colcount; j++)
476 1593 : TupleDescCopyEntry(scan_tupdesc, ++attno, tupdesc, j);
477 : }
478 :
479 : /* If doing ordinality, add a column of type "bigint" at the end */
480 962 : if (node->funcordinality)
481 : {
482 915 : TupleDescInitEntry(scan_tupdesc,
483 : ++attno,
484 : NULL, /* don't care about the name here */
485 : INT8OID,
486 : -1,
487 : 0);
488 : }
489 :
490 962 : TupleDescFinalize(scan_tupdesc);
491 : Assert(attno == natts);
492 : }
493 :
494 : /*
495 : * Initialize scan slot and type.
496 : */
497 44370 : ExecInitScanTupleSlot(estate, &scanstate->ss, scan_tupdesc,
498 : &TTSOpsMinimalTuple, 0);
499 :
500 : /*
501 : * Initialize result slot, type and projection.
502 : */
503 44370 : ExecInitResultTypeTL(&scanstate->ss.ps);
504 44370 : ExecAssignScanProjectionInfo(&scanstate->ss);
505 :
506 : /*
507 : * initialize child expressions
508 : */
509 44370 : scanstate->ss.ps.qual =
510 44370 : ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
511 :
512 : /*
513 : * Create a memory context that ExecMakeTableFunctionResult can use to
514 : * evaluate function arguments in. We can't use the per-tuple context for
515 : * this because it gets reset too often; but we don't want to leak
516 : * evaluation results into the query-lifespan context either. We just
517 : * need one context, because we evaluate each function separately.
518 : */
519 44370 : scanstate->argcontext = AllocSetContextCreate(CurrentMemoryContext,
520 : "Table function arguments",
521 : ALLOCSET_DEFAULT_SIZES);
522 :
523 44370 : return scanstate;
524 : }
525 :
526 : /* ----------------------------------------------------------------
527 : * ExecEndFunctionScan
528 : *
529 : * frees any storage allocated through C routines.
530 : * ----------------------------------------------------------------
531 : */
532 : void
533 40871 : ExecEndFunctionScan(FunctionScanState *node)
534 : {
535 : int i;
536 :
537 : /*
538 : * Release slots and tuplestore resources
539 : */
540 81939 : for (i = 0; i < node->nfuncs; i++)
541 : {
542 41068 : FunctionScanPerFuncState *fs = &node->funcstates[i];
543 :
544 41068 : if (fs->tstore != NULL)
545 : {
546 36490 : tuplestore_end(node->funcstates[i].tstore);
547 36490 : fs->tstore = NULL;
548 : }
549 : }
550 40871 : }
551 :
552 : /* ----------------------------------------------------------------
553 : * ExecReScanFunctionScan
554 : *
555 : * Rescans the relation.
556 : * ----------------------------------------------------------------
557 : */
558 : void
559 80543 : ExecReScanFunctionScan(FunctionScanState *node)
560 : {
561 80543 : FunctionScan *scan = (FunctionScan *) node->ss.ps.plan;
562 : int i;
563 80543 : Bitmapset *chgparam = node->ss.ps.chgParam;
564 :
565 80543 : if (node->ss.ps.ps_ResultTupleSlot)
566 32008 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
567 161159 : for (i = 0; i < node->nfuncs; i++)
568 : {
569 80616 : FunctionScanPerFuncState *fs = &node->funcstates[i];
570 :
571 80616 : if (fs->func_slot)
572 742 : ExecClearTuple(fs->func_slot);
573 : }
574 :
575 80543 : ExecScanReScan(&node->ss);
576 :
577 : /*
578 : * Here we have a choice whether to drop the tuplestores (and recompute
579 : * the function outputs) or just rescan them. We must recompute if an
580 : * expression contains changed parameters, else we rescan.
581 : *
582 : * XXX maybe we should recompute if the function is volatile? But in
583 : * general the executor doesn't conditionalize its actions on that.
584 : */
585 80543 : if (chgparam)
586 : {
587 : ListCell *lc;
588 :
589 71081 : i = 0;
590 142219 : foreach(lc, scan->functions)
591 : {
592 71138 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
593 :
594 71138 : if (bms_overlap(chgparam, rtfunc->funcparams))
595 : {
596 68142 : if (node->funcstates[i].tstore != NULL)
597 : {
598 61768 : tuplestore_end(node->funcstates[i].tstore);
599 61768 : node->funcstates[i].tstore = NULL;
600 : }
601 68142 : node->funcstates[i].rowcount = -1;
602 : }
603 71138 : i++;
604 : }
605 : }
606 :
607 : /* Reset ordinality counter */
608 80543 : node->ordinal = 0;
609 :
610 : /* Make sure we rewind any remaining tuplestores */
611 161159 : for (i = 0; i < node->nfuncs; i++)
612 : {
613 80616 : if (node->funcstates[i].tstore != NULL)
614 11773 : tuplestore_rescan(node->funcstates[i].tstore);
615 : }
616 80543 : }
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