Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeFunctionscan.c
4 : * Support routines for scanning RangeFunctions (functions in rangetable).
5 : *
6 : * Portions Copyright (c) 1996-2024, 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 :
31 :
32 : /*
33 : * Runtime data for each function being scanned.
34 : */
35 : typedef struct FunctionScanPerFuncState
36 : {
37 : SetExprState *setexpr; /* state of the expression being evaluated */
38 : TupleDesc tupdesc; /* desc of the function result type */
39 : int colcount; /* expected number of result columns */
40 : Tuplestorestate *tstore; /* holds the function result set */
41 : int64 rowcount; /* # of rows in result set, -1 if not known */
42 : TupleTableSlot *func_slot; /* function result slot (or NULL) */
43 : } FunctionScanPerFuncState;
44 :
45 : static TupleTableSlot *FunctionNext(FunctionScanState *node);
46 :
47 :
48 : /* ----------------------------------------------------------------
49 : * Scan Support
50 : * ----------------------------------------------------------------
51 : */
52 : /* ----------------------------------------------------------------
53 : * FunctionNext
54 : *
55 : * This is a workhorse for ExecFunctionScan
56 : * ----------------------------------------------------------------
57 : */
58 : static TupleTableSlot *
59 15720694 : FunctionNext(FunctionScanState *node)
60 : {
61 : EState *estate;
62 : ScanDirection direction;
63 : TupleTableSlot *scanslot;
64 : bool alldone;
65 : int64 oldpos;
66 : int funcno;
67 : int att;
68 :
69 : /*
70 : * get information from the estate and scan state
71 : */
72 15720694 : estate = node->ss.ps.state;
73 15720694 : direction = estate->es_direction;
74 15720694 : scanslot = node->ss.ss_ScanTupleSlot;
75 :
76 15720694 : if (node->simple)
77 : {
78 : /*
79 : * Fast path for the trivial case: the function return type and scan
80 : * result type are the same, so we fetch the function result straight
81 : * into the scan result slot. No need to update ordinality or
82 : * rowcounts either.
83 : */
84 15701584 : Tuplestorestate *tstore = node->funcstates[0].tstore;
85 :
86 : /*
87 : * If first time through, read all tuples from function and put them
88 : * in a tuplestore. Subsequent calls just fetch tuples from
89 : * tuplestore.
90 : */
91 15701584 : if (tstore == NULL)
92 : {
93 140948 : node->funcstates[0].tstore = tstore =
94 146108 : ExecMakeTableFunctionResult(node->funcstates[0].setexpr,
95 : node->ss.ps.ps_ExprContext,
96 : node->argcontext,
97 146108 : node->funcstates[0].tupdesc,
98 146108 : node->eflags & EXEC_FLAG_BACKWARD);
99 :
100 : /*
101 : * paranoia - cope if the function, which may have constructed the
102 : * tuplestore itself, didn't leave it pointing at the start. This
103 : * call is fast, so the overhead shouldn't be an issue.
104 : */
105 140948 : tuplestore_rescan(tstore);
106 : }
107 :
108 : /*
109 : * Get the next tuple from tuplestore.
110 : */
111 15696424 : (void) tuplestore_gettupleslot(tstore,
112 : ScanDirectionIsForward(direction),
113 : false,
114 : scanslot);
115 15696424 : return scanslot;
116 : }
117 :
118 : /*
119 : * Increment or decrement ordinal counter before checking for end-of-data,
120 : * so that we can move off either end of the result by 1 (and no more than
121 : * 1) without losing correct count. See PortalRunSelect for why we can
122 : * assume that we won't be called repeatedly in the end-of-data state.
123 : */
124 19110 : oldpos = node->ordinal;
125 19110 : if (ScanDirectionIsForward(direction))
126 19050 : node->ordinal++;
127 : else
128 60 : node->ordinal--;
129 :
130 : /*
131 : * Main loop over functions.
132 : *
133 : * We fetch the function results into func_slots (which match the function
134 : * return types), and then copy the values to scanslot (which matches the
135 : * scan result type), setting the ordinal column (if any) as well.
136 : */
137 19110 : ExecClearTuple(scanslot);
138 19110 : att = 0;
139 19110 : alldone = true;
140 49190 : for (funcno = 0; funcno < node->nfuncs; funcno++)
141 : {
142 30080 : FunctionScanPerFuncState *fs = &node->funcstates[funcno];
143 : int i;
144 :
145 : /*
146 : * If first time through, read all tuples from function and put them
147 : * in a tuplestore. Subsequent calls just fetch tuples from
148 : * tuplestore.
149 : */
150 30080 : if (fs->tstore == NULL)
151 : {
152 1764 : fs->tstore =
153 1764 : ExecMakeTableFunctionResult(fs->setexpr,
154 : node->ss.ps.ps_ExprContext,
155 : node->argcontext,
156 : fs->tupdesc,
157 1764 : node->eflags & EXEC_FLAG_BACKWARD);
158 :
159 : /*
160 : * paranoia - cope if the function, which may have constructed the
161 : * tuplestore itself, didn't leave it pointing at the start. This
162 : * call is fast, so the overhead shouldn't be an issue.
163 : */
164 1764 : tuplestore_rescan(fs->tstore);
165 : }
166 :
167 : /*
168 : * Get the next tuple from tuplestore.
169 : *
170 : * If we have a rowcount for the function, and we know the previous
171 : * read position was out of bounds, don't try the read. This allows
172 : * backward scan to work when there are mixed row counts present.
173 : */
174 30080 : if (fs->rowcount != -1 && fs->rowcount < oldpos)
175 72 : ExecClearTuple(fs->func_slot);
176 : else
177 30008 : (void) tuplestore_gettupleslot(fs->tstore,
178 : ScanDirectionIsForward(direction),
179 : false,
180 : fs->func_slot);
181 :
182 30080 : if (TupIsNull(fs->func_slot))
183 : {
184 : /*
185 : * If we ran out of data for this function in the forward
186 : * direction then we now know how many rows it returned. We need
187 : * to know this in order to handle backwards scans. The row count
188 : * we store is actually 1+ the actual number, because we have to
189 : * position the tuplestore 1 off its end sometimes.
190 : */
191 2112 : if (ScanDirectionIsForward(direction) && fs->rowcount == -1)
192 1740 : fs->rowcount = node->ordinal;
193 :
194 : /*
195 : * populate the result cols with nulls
196 : */
197 5212 : for (i = 0; i < fs->colcount; i++)
198 : {
199 3100 : scanslot->tts_values[att] = (Datum) 0;
200 3100 : scanslot->tts_isnull[att] = true;
201 3100 : att++;
202 : }
203 : }
204 : else
205 : {
206 : /*
207 : * we have a result, so just copy it to the result cols.
208 : */
209 27968 : slot_getallattrs(fs->func_slot);
210 :
211 73586 : for (i = 0; i < fs->colcount; i++)
212 : {
213 45618 : scanslot->tts_values[att] = fs->func_slot->tts_values[i];
214 45618 : scanslot->tts_isnull[att] = fs->func_slot->tts_isnull[i];
215 45618 : att++;
216 : }
217 :
218 : /*
219 : * We're not done until every function result is exhausted; we pad
220 : * the shorter results with nulls until then.
221 : */
222 27968 : alldone = false;
223 : }
224 : }
225 :
226 : /*
227 : * ordinal col is always last, per spec.
228 : */
229 19110 : if (node->ordinality)
230 : {
231 13862 : scanslot->tts_values[att] = Int64GetDatumFast(node->ordinal);
232 13862 : scanslot->tts_isnull[att] = false;
233 : }
234 :
235 : /*
236 : * If alldone, we just return the previously-cleared scanslot. Otherwise,
237 : * finish creating the virtual tuple.
238 : */
239 19110 : if (!alldone)
240 17634 : ExecStoreVirtualTuple(scanslot);
241 :
242 19110 : return scanslot;
243 : }
244 :
245 : /*
246 : * FunctionRecheck -- access method routine to recheck a tuple in EvalPlanQual
247 : */
248 : static bool
249 0 : FunctionRecheck(FunctionScanState *node, TupleTableSlot *slot)
250 : {
251 : /* nothing to check */
252 0 : return true;
253 : }
254 :
255 : /* ----------------------------------------------------------------
256 : * ExecFunctionScan(node)
257 : *
258 : * Scans the function sequentially and returns the next qualifying
259 : * tuple.
260 : * We call the ExecScan() routine and pass it the appropriate
261 : * access method functions.
262 : * ----------------------------------------------------------------
263 : */
264 : static TupleTableSlot *
265 14093064 : ExecFunctionScan(PlanState *pstate)
266 : {
267 14093064 : FunctionScanState *node = castNode(FunctionScanState, pstate);
268 :
269 14093064 : return ExecScan(&node->ss,
270 : (ExecScanAccessMtd) FunctionNext,
271 : (ExecScanRecheckMtd) FunctionRecheck);
272 : }
273 :
274 : /* ----------------------------------------------------------------
275 : * ExecInitFunctionScan
276 : * ----------------------------------------------------------------
277 : */
278 : FunctionScanState *
279 63954 : ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
280 : {
281 : FunctionScanState *scanstate;
282 63954 : int nfuncs = list_length(node->functions);
283 : TupleDesc scan_tupdesc;
284 : int i,
285 : natts;
286 : ListCell *lc;
287 :
288 : /* check for unsupported flags */
289 : Assert(!(eflags & EXEC_FLAG_MARK));
290 :
291 : /*
292 : * FunctionScan should not have any children.
293 : */
294 : Assert(outerPlan(node) == NULL);
295 : Assert(innerPlan(node) == NULL);
296 :
297 : /*
298 : * create new ScanState for node
299 : */
300 63954 : scanstate = makeNode(FunctionScanState);
301 63954 : scanstate->ss.ps.plan = (Plan *) node;
302 63954 : scanstate->ss.ps.state = estate;
303 63954 : scanstate->ss.ps.ExecProcNode = ExecFunctionScan;
304 63954 : scanstate->eflags = eflags;
305 :
306 : /*
307 : * are we adding an ordinality column?
308 : */
309 63954 : scanstate->ordinality = node->funcordinality;
310 :
311 63954 : scanstate->nfuncs = nfuncs;
312 63954 : if (nfuncs == 1 && !node->funcordinality)
313 63034 : scanstate->simple = true;
314 : else
315 920 : scanstate->simple = false;
316 :
317 : /*
318 : * Ordinal 0 represents the "before the first row" position.
319 : *
320 : * We need to track ordinal position even when not adding an ordinality
321 : * column to the result, in order to handle backwards scanning properly
322 : * with multiple functions with different result sizes. (We can't position
323 : * any individual function's tuplestore any more than 1 place beyond its
324 : * end, so when scanning backwards, we need to know when to start
325 : * including the function in the scan again.)
326 : */
327 63954 : scanstate->ordinal = 0;
328 :
329 : /*
330 : * Miscellaneous initialization
331 : *
332 : * create expression context for node
333 : */
334 63954 : ExecAssignExprContext(estate, &scanstate->ss.ps);
335 :
336 63954 : scanstate->funcstates = palloc(nfuncs * sizeof(FunctionScanPerFuncState));
337 :
338 63954 : natts = 0;
339 63954 : i = 0;
340 128212 : foreach(lc, node->functions)
341 : {
342 64266 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
343 64266 : Node *funcexpr = rtfunc->funcexpr;
344 64266 : int colcount = rtfunc->funccolcount;
345 64266 : FunctionScanPerFuncState *fs = &scanstate->funcstates[i];
346 : TupleDesc tupdesc;
347 :
348 64258 : fs->setexpr =
349 64266 : ExecInitTableFunctionResult((Expr *) funcexpr,
350 : scanstate->ss.ps.ps_ExprContext,
351 : &scanstate->ss.ps);
352 :
353 : /*
354 : * Don't allocate the tuplestores; the actual calls to the functions
355 : * do that. NULL means that we have not called the function yet (or
356 : * need to call it again after a rescan).
357 : */
358 64258 : fs->tstore = NULL;
359 64258 : fs->rowcount = -1;
360 :
361 : /*
362 : * Now build a tupdesc showing the result type we expect from the
363 : * function. If we have a coldeflist then that takes priority (note
364 : * the parser enforces that there is one if the function's nominal
365 : * output type is RECORD). Otherwise use get_expr_result_type.
366 : *
367 : * Note that if the function returns a named composite type, that may
368 : * now contain more or different columns than it did when the plan was
369 : * made. For both that and the RECORD case, we need to check tuple
370 : * compatibility. ExecMakeTableFunctionResult handles some of this,
371 : * and CheckVarSlotCompatibility provides a backstop.
372 : */
373 64258 : if (rtfunc->funccolnames != NIL)
374 : {
375 1520 : tupdesc = BuildDescFromLists(rtfunc->funccolnames,
376 760 : rtfunc->funccoltypes,
377 760 : rtfunc->funccoltypmods,
378 760 : rtfunc->funccolcollations);
379 :
380 : /*
381 : * For RECORD results, make sure a typmod has been assigned. (The
382 : * function should do this for itself, but let's cover things in
383 : * case it doesn't.)
384 : */
385 760 : BlessTupleDesc(tupdesc);
386 : }
387 : else
388 : {
389 : TypeFuncClass functypclass;
390 : Oid funcrettype;
391 :
392 63498 : functypclass = get_expr_result_type(funcexpr,
393 : &funcrettype,
394 : &tupdesc);
395 :
396 63498 : if (functypclass == TYPEFUNC_COMPOSITE ||
397 : functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
398 : {
399 : /* Composite data type, e.g. a table's row type */
400 : Assert(tupdesc);
401 : /* Must copy it out of typcache for safety */
402 37352 : tupdesc = CreateTupleDescCopy(tupdesc);
403 : }
404 26146 : else if (functypclass == TYPEFUNC_SCALAR)
405 : {
406 : /* Base data type, i.e. scalar */
407 26146 : tupdesc = CreateTemplateTupleDesc(1);
408 26146 : TupleDescInitEntry(tupdesc,
409 : (AttrNumber) 1,
410 : NULL, /* don't care about the name here */
411 : funcrettype,
412 : -1,
413 : 0);
414 26146 : TupleDescInitEntryCollation(tupdesc,
415 : (AttrNumber) 1,
416 : exprCollation(funcexpr));
417 : }
418 : else
419 : {
420 : /* crummy error message, but parser should have caught this */
421 0 : elog(ERROR, "function in FROM has unsupported return type");
422 : }
423 : }
424 :
425 64258 : fs->tupdesc = tupdesc;
426 64258 : fs->colcount = colcount;
427 :
428 : /*
429 : * We only need separate slots for the function results if we are
430 : * doing ordinality or multiple functions; otherwise, we'll fetch
431 : * function results directly into the scan slot.
432 : */
433 64258 : if (!scanstate->simple)
434 : {
435 1232 : fs->func_slot = ExecInitExtraTupleSlot(estate, fs->tupdesc,
436 : &TTSOpsMinimalTuple);
437 : }
438 : else
439 63026 : fs->func_slot = NULL;
440 :
441 64258 : natts += colcount;
442 64258 : i++;
443 : }
444 :
445 : /*
446 : * Create the combined TupleDesc
447 : *
448 : * If there is just one function without ordinality, the scan result
449 : * tupdesc is the same as the function result tupdesc --- except that we
450 : * may stuff new names into it below, so drop any rowtype label.
451 : */
452 63946 : if (scanstate->simple)
453 : {
454 63026 : scan_tupdesc = CreateTupleDescCopy(scanstate->funcstates[0].tupdesc);
455 63026 : scan_tupdesc->tdtypeid = RECORDOID;
456 63026 : scan_tupdesc->tdtypmod = -1;
457 : }
458 : else
459 : {
460 920 : AttrNumber attno = 0;
461 :
462 920 : if (node->funcordinality)
463 848 : natts++;
464 :
465 920 : scan_tupdesc = CreateTemplateTupleDesc(natts);
466 :
467 2152 : for (i = 0; i < nfuncs; i++)
468 : {
469 1232 : TupleDesc tupdesc = scanstate->funcstates[i].tupdesc;
470 1232 : int colcount = scanstate->funcstates[i].colcount;
471 : int j;
472 :
473 3104 : for (j = 1; j <= colcount; j++)
474 1872 : TupleDescCopyEntry(scan_tupdesc, ++attno, tupdesc, j);
475 : }
476 :
477 : /* If doing ordinality, add a column of type "bigint" at the end */
478 920 : if (node->funcordinality)
479 : {
480 848 : TupleDescInitEntry(scan_tupdesc,
481 : ++attno,
482 : NULL, /* don't care about the name here */
483 : INT8OID,
484 : -1,
485 : 0);
486 : }
487 :
488 : Assert(attno == natts);
489 : }
490 :
491 : /*
492 : * Initialize scan slot and type.
493 : */
494 63946 : ExecInitScanTupleSlot(estate, &scanstate->ss, scan_tupdesc,
495 : &TTSOpsMinimalTuple);
496 :
497 : /*
498 : * Initialize result slot, type and projection.
499 : */
500 63946 : ExecInitResultTypeTL(&scanstate->ss.ps);
501 63946 : ExecAssignScanProjectionInfo(&scanstate->ss);
502 :
503 : /*
504 : * initialize child expressions
505 : */
506 63946 : scanstate->ss.ps.qual =
507 63946 : ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
508 :
509 : /*
510 : * Create a memory context that ExecMakeTableFunctionResult can use to
511 : * evaluate function arguments in. We can't use the per-tuple context for
512 : * this because it gets reset too often; but we don't want to leak
513 : * evaluation results into the query-lifespan context either. We just
514 : * need one context, because we evaluate each function separately.
515 : */
516 63946 : scanstate->argcontext = AllocSetContextCreate(CurrentMemoryContext,
517 : "Table function arguments",
518 : ALLOCSET_DEFAULT_SIZES);
519 :
520 63946 : return scanstate;
521 : }
522 :
523 : /* ----------------------------------------------------------------
524 : * ExecEndFunctionScan
525 : *
526 : * frees any storage allocated through C routines.
527 : * ----------------------------------------------------------------
528 : */
529 : void
530 58594 : ExecEndFunctionScan(FunctionScanState *node)
531 : {
532 : int i;
533 :
534 : /*
535 : * Release slots and tuplestore resources
536 : */
537 117488 : for (i = 0; i < node->nfuncs; i++)
538 : {
539 58894 : FunctionScanPerFuncState *fs = &node->funcstates[i];
540 :
541 58894 : if (fs->tstore != NULL)
542 : {
543 53634 : tuplestore_end(node->funcstates[i].tstore);
544 53634 : fs->tstore = NULL;
545 : }
546 : }
547 58594 : }
548 :
549 : /* ----------------------------------------------------------------
550 : * ExecReScanFunctionScan
551 : *
552 : * Rescans the relation.
553 : * ----------------------------------------------------------------
554 : */
555 : void
556 112808 : ExecReScanFunctionScan(FunctionScanState *node)
557 : {
558 112808 : FunctionScan *scan = (FunctionScan *) node->ss.ps.plan;
559 : int i;
560 112808 : Bitmapset *chgparam = node->ss.ps.chgParam;
561 :
562 112808 : if (node->ss.ps.ps_ResultTupleSlot)
563 54524 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
564 225724 : for (i = 0; i < node->nfuncs; i++)
565 : {
566 112916 : FunctionScanPerFuncState *fs = &node->funcstates[i];
567 :
568 112916 : if (fs->func_slot)
569 1086 : ExecClearTuple(fs->func_slot);
570 : }
571 :
572 112808 : ExecScanReScan(&node->ss);
573 :
574 : /*
575 : * Here we have a choice whether to drop the tuplestores (and recompute
576 : * the function outputs) or just rescan them. We must recompute if an
577 : * expression contains changed parameters, else we rescan.
578 : *
579 : * XXX maybe we should recompute if the function is volatile? But in
580 : * general the executor doesn't conditionalize its actions on that.
581 : */
582 112808 : if (chgparam)
583 : {
584 : ListCell *lc;
585 :
586 105830 : i = 0;
587 211744 : foreach(lc, scan->functions)
588 : {
589 105914 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
590 :
591 105914 : if (bms_overlap(chgparam, rtfunc->funcparams))
592 : {
593 100252 : if (node->funcstates[i].tstore != NULL)
594 : {
595 88874 : tuplestore_end(node->funcstates[i].tstore);
596 88874 : node->funcstates[i].tstore = NULL;
597 : }
598 100252 : node->funcstates[i].rowcount = -1;
599 : }
600 105914 : i++;
601 : }
602 : }
603 :
604 : /* Reset ordinality counter */
605 112808 : node->ordinal = 0;
606 :
607 : /* Make sure we rewind any remaining tuplestores */
608 225724 : for (i = 0; i < node->nfuncs; i++)
609 : {
610 112916 : if (node->funcstates[i].tstore != NULL)
611 11806 : tuplestore_rescan(node->funcstates[i].tstore);
612 : }
613 112808 : }
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