TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeFunctionscan.c
4 : * Support routines for scanning RangeFunctions (functions in rangetable).
5 : *
6 : * Portions Copyright (c) 1996-2023, 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/builtins.h"
30 : #include "utils/memutils.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 CBC 7482234 : 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 7482234 : estate = node->ss.ps.state;
74 7482234 : direction = estate->es_direction;
75 7482234 : scanslot = node->ss.ss_ScanTupleSlot;
76 :
77 7482234 : 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 7472856 : 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 7472856 : if (tstore == NULL)
93 : {
94 53135 : node->funcstates[0].tstore = tstore =
95 55665 : ExecMakeTableFunctionResult(node->funcstates[0].setexpr,
96 : node->ss.ps.ps_ExprContext,
97 : node->argcontext,
98 55665 : node->funcstates[0].tupdesc,
99 55665 : 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 53135 : tuplestore_rescan(tstore);
107 : }
108 :
109 : /*
110 : * Get the next tuple from tuplestore.
111 : */
112 7470326 : (void) tuplestore_gettupleslot(tstore,
113 : ScanDirectionIsForward(direction),
114 : false,
115 : scanslot);
116 7470326 : 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 9378 : oldpos = node->ordinal;
126 9378 : if (ScanDirectionIsForward(direction))
127 9348 : node->ordinal++;
128 : else
129 30 : 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 9378 : ExecClearTuple(scanslot);
139 9378 : att = 0;
140 9378 : alldone = true;
141 24225 : for (funcno = 0; funcno < node->nfuncs; funcno++)
142 : {
143 14847 : 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 14847 : if (fs->tstore == NULL)
152 : {
153 803 : fs->tstore =
154 803 : ExecMakeTableFunctionResult(fs->setexpr,
155 : node->ss.ps.ps_ExprContext,
156 : node->argcontext,
157 : fs->tupdesc,
158 803 : 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 : */
165 803 : 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 14847 : if (fs->rowcount != -1 && fs->rowcount < oldpos)
176 36 : ExecClearTuple(fs->func_slot);
177 : else
178 14811 : (void) tuplestore_gettupleslot(fs->tstore,
179 : ScanDirectionIsForward(direction),
180 : false,
181 : fs->func_slot);
182 :
183 14847 : 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 : */
192 977 : if (ScanDirectionIsForward(direction) && fs->rowcount == -1)
193 791 : fs->rowcount = node->ordinal;
194 :
195 : /*
196 : * populate the result cols with nulls
197 : */
198 2448 : for (i = 0; i < fs->colcount; i++)
199 : {
200 1471 : scanslot->tts_values[att] = (Datum) 0;
201 1471 : scanslot->tts_isnull[att] = true;
202 1471 : att++;
203 : }
204 : }
205 : else
206 : {
207 : /*
208 : * we have a result, so just copy it to the result cols.
209 : */
210 13870 : slot_getallattrs(fs->func_slot);
211 :
212 36565 : for (i = 0; i < fs->colcount; i++)
213 : {
214 22695 : scanslot->tts_values[att] = fs->func_slot->tts_values[i];
215 22695 : scanslot->tts_isnull[att] = fs->func_slot->tts_isnull[i];
216 22695 : 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 13870 : alldone = false;
224 : }
225 : }
226 :
227 : /*
228 : * ordinal col is always last, per spec.
229 : */
230 9378 : if (node->ordinality)
231 : {
232 6762 : scanslot->tts_values[att] = Int64GetDatumFast(node->ordinal);
233 6762 : 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 9378 : if (!alldone)
241 8719 : ExecStoreVirtualTuple(scanslot);
242 :
243 9378 : return scanslot;
244 : }
245 :
246 : /*
247 : * FunctionRecheck -- access method routine to recheck a tuple in EvalPlanQual
248 : */
249 : static bool
250 UBC 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 CBC 6962048 : ExecFunctionScan(PlanState *pstate)
267 : {
268 6962048 : FunctionScanState *node = castNode(FunctionScanState, pstate);
269 :
270 6962048 : return ExecScan(&node->ss,
271 : (ExecScanAccessMtd) FunctionNext,
272 : (ExecScanRecheckMtd) FunctionRecheck);
273 : }
274 :
275 : /* ----------------------------------------------------------------
276 : * ExecInitFunctionScan
277 : * ----------------------------------------------------------------
278 : */
279 : FunctionScanState *
280 26789 : ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
281 : {
282 : FunctionScanState *scanstate;
283 26789 : 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 26789 : Assert(!(eflags & EXEC_FLAG_MARK));
291 :
292 : /*
293 : * FunctionScan should not have any children.
294 : */
295 26789 : Assert(outerPlan(node) == NULL);
296 26789 : Assert(innerPlan(node) == NULL);
297 :
298 : /*
299 : * create new ScanState for node
300 : */
301 26789 : scanstate = makeNode(FunctionScanState);
302 26789 : scanstate->ss.ps.plan = (Plan *) node;
303 26789 : scanstate->ss.ps.state = estate;
304 26789 : scanstate->ss.ps.ExecProcNode = ExecFunctionScan;
305 26789 : scanstate->eflags = eflags;
306 :
307 : /*
308 : * are we adding an ordinality column?
309 : */
310 26789 : scanstate->ordinality = node->funcordinality;
311 :
312 26789 : scanstate->nfuncs = nfuncs;
313 26789 : if (nfuncs == 1 && !node->funcordinality)
314 26445 : scanstate->simple = true;
315 : else
316 344 : 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 26789 : scanstate->ordinal = 0;
329 :
330 : /*
331 : * Miscellaneous initialization
332 : *
333 : * create expression context for node
334 : */
335 26789 : ExecAssignExprContext(estate, &scanstate->ss.ps);
336 :
337 26789 : scanstate->funcstates = palloc(nfuncs * sizeof(FunctionScanPerFuncState));
338 :
339 26789 : natts = 0;
340 26789 : i = 0;
341 53730 : foreach(lc, node->functions)
342 : {
343 26945 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
344 26945 : Node *funcexpr = rtfunc->funcexpr;
345 26945 : int colcount = rtfunc->funccolcount;
346 26945 : FunctionScanPerFuncState *fs = &scanstate->funcstates[i];
347 : TypeFuncClass functypclass;
348 : Oid funcrettype;
349 : TupleDesc tupdesc;
350 :
351 26941 : fs->setexpr =
352 26945 : ExecInitTableFunctionResult((Expr *) funcexpr,
353 : scanstate->ss.ps.ps_ExprContext,
354 : &scanstate->ss.ps);
355 :
356 : /*
357 : * Don't allocate the tuplestores; the actual calls to the functions
358 : * do that. NULL means that we have not called the function yet (or
359 : * need to call it again after a rescan).
360 : */
361 26941 : fs->tstore = NULL;
362 26941 : fs->rowcount = -1;
363 :
364 : /*
365 : * Now determine if the function returns a simple or composite type,
366 : * and build an appropriate tupdesc. Note that in the composite case,
367 : * the function may now return more columns than it did when the plan
368 : * was made; we have to ignore any columns beyond "colcount".
369 : */
370 26941 : functypclass = get_expr_result_type(funcexpr,
371 : &funcrettype,
372 : &tupdesc);
373 :
374 26941 : if (functypclass == TYPEFUNC_COMPOSITE ||
375 : functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
376 : {
377 : /* Composite data type, e.g. a table's row type */
378 15948 : Assert(tupdesc);
379 15948 : Assert(tupdesc->natts >= colcount);
380 : /* Must copy it out of typcache for safety */
381 15948 : tupdesc = CreateTupleDescCopy(tupdesc);
382 : }
383 10993 : else if (functypclass == TYPEFUNC_SCALAR)
384 : {
385 : /* Base data type, i.e. scalar */
386 10643 : tupdesc = CreateTemplateTupleDesc(1);
387 10643 : TupleDescInitEntry(tupdesc,
388 : (AttrNumber) 1,
389 : NULL, /* don't care about the name here */
390 : funcrettype,
391 : -1,
392 : 0);
393 10643 : TupleDescInitEntryCollation(tupdesc,
394 : (AttrNumber) 1,
395 : exprCollation(funcexpr));
396 : }
397 350 : else if (functypclass == TYPEFUNC_RECORD)
398 : {
399 350 : tupdesc = BuildDescFromLists(rtfunc->funccolnames,
400 : rtfunc->funccoltypes,
401 : rtfunc->funccoltypmods,
402 : rtfunc->funccolcollations);
403 :
404 : /*
405 : * For RECORD results, make sure a typmod has been assigned. (The
406 : * function should do this for itself, but let's cover things in
407 : * case it doesn't.)
408 : */
409 350 : BlessTupleDesc(tupdesc);
410 : }
411 : else
412 : {
413 : /* crummy error message, but parser should have caught this */
414 UBC 0 : elog(ERROR, "function in FROM has unsupported return type");
415 : }
416 :
417 CBC 26941 : fs->tupdesc = tupdesc;
418 26941 : fs->colcount = colcount;
419 :
420 : /*
421 : * We only need separate slots for the function results if we are
422 : * doing ordinality or multiple functions; otherwise, we'll fetch
423 : * function results directly into the scan slot.
424 : */
425 26941 : if (!scanstate->simple)
426 : {
427 500 : fs->func_slot = ExecInitExtraTupleSlot(estate, fs->tupdesc,
428 : &TTSOpsMinimalTuple);
429 : }
430 : else
431 26441 : fs->func_slot = NULL;
432 :
433 26941 : natts += colcount;
434 26941 : i++;
435 : }
436 :
437 : /*
438 : * Create the combined TupleDesc
439 : *
440 : * If there is just one function without ordinality, the scan result
441 : * tupdesc is the same as the function result tupdesc --- except that we
442 : * may stuff new names into it below, so drop any rowtype label.
443 : */
444 26785 : if (scanstate->simple)
445 : {
446 26441 : scan_tupdesc = CreateTupleDescCopy(scanstate->funcstates[0].tupdesc);
447 26441 : scan_tupdesc->tdtypeid = RECORDOID;
448 26441 : scan_tupdesc->tdtypmod = -1;
449 : }
450 : else
451 : {
452 344 : AttrNumber attno = 0;
453 :
454 344 : if (node->funcordinality)
455 308 : natts++;
456 :
457 344 : scan_tupdesc = CreateTemplateTupleDesc(natts);
458 :
459 844 : for (i = 0; i < nfuncs; i++)
460 : {
461 500 : TupleDesc tupdesc = scanstate->funcstates[i].tupdesc;
462 500 : int colcount = scanstate->funcstates[i].colcount;
463 : int j;
464 :
465 1320 : for (j = 1; j <= colcount; j++)
466 820 : TupleDescCopyEntry(scan_tupdesc, ++attno, tupdesc, j);
467 : }
468 :
469 : /* If doing ordinality, add a column of type "bigint" at the end */
470 344 : if (node->funcordinality)
471 : {
472 308 : TupleDescInitEntry(scan_tupdesc,
473 : ++attno,
474 : NULL, /* don't care about the name here */
475 : INT8OID,
476 : -1,
477 : 0);
478 : }
479 :
480 344 : Assert(attno == natts);
481 : }
482 :
483 : /*
484 : * Initialize scan slot and type.
485 : */
486 26785 : ExecInitScanTupleSlot(estate, &scanstate->ss, scan_tupdesc,
487 : &TTSOpsMinimalTuple);
488 :
489 : /*
490 : * Initialize result slot, type and projection.
491 : */
492 26785 : ExecInitResultTypeTL(&scanstate->ss.ps);
493 26785 : ExecAssignScanProjectionInfo(&scanstate->ss);
494 :
495 : /*
496 : * initialize child expressions
497 : */
498 26785 : scanstate->ss.ps.qual =
499 26785 : ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
500 :
501 : /*
502 : * Create a memory context that ExecMakeTableFunctionResult can use to
503 : * evaluate function arguments in. We can't use the per-tuple context for
504 : * this because it gets reset too often; but we don't want to leak
505 : * evaluation results into the query-lifespan context either. We just
506 : * need one context, because we evaluate each function separately.
507 : */
508 26785 : scanstate->argcontext = AllocSetContextCreate(CurrentMemoryContext,
509 : "Table function arguments",
510 : ALLOCSET_DEFAULT_SIZES);
511 :
512 26785 : return scanstate;
513 : }
514 :
515 : /* ----------------------------------------------------------------
516 : * ExecEndFunctionScan
517 : *
518 : * frees any storage allocated through C routines.
519 : * ----------------------------------------------------------------
520 : */
521 : void
522 24172 : ExecEndFunctionScan(FunctionScanState *node)
523 : {
524 : int i;
525 :
526 : /*
527 : * Free the exprcontext
528 : */
529 24172 : ExecFreeExprContext(&node->ss.ps);
530 :
531 : /*
532 : * clean out the tuple table
533 : */
534 24172 : if (node->ss.ps.ps_ResultTupleSlot)
535 8523 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
536 24172 : ExecClearTuple(node->ss.ss_ScanTupleSlot);
537 :
538 : /*
539 : * Release slots and tuplestore resources
540 : */
541 48494 : for (i = 0; i < node->nfuncs; i++)
542 : {
543 24322 : FunctionScanPerFuncState *fs = &node->funcstates[i];
544 :
545 24322 : if (fs->func_slot)
546 488 : ExecClearTuple(fs->func_slot);
547 :
548 24322 : if (fs->tstore != NULL)
549 : {
550 22233 : tuplestore_end(node->funcstates[i].tstore);
551 22233 : fs->tstore = NULL;
552 : }
553 : }
554 24172 : }
555 :
556 : /* ----------------------------------------------------------------
557 : * ExecReScanFunctionScan
558 : *
559 : * Rescans the relation.
560 : * ----------------------------------------------------------------
561 : */
562 : void
563 38925 : ExecReScanFunctionScan(FunctionScanState *node)
564 : {
565 38925 : FunctionScan *scan = (FunctionScan *) node->ss.ps.plan;
566 : int i;
567 38925 : Bitmapset *chgparam = node->ss.ps.chgParam;
568 :
569 38925 : if (node->ss.ps.ps_ResultTupleSlot)
570 20344 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
571 77904 : for (i = 0; i < node->nfuncs; i++)
572 : {
573 38979 : FunctionScanPerFuncState *fs = &node->funcstates[i];
574 :
575 38979 : if (fs->func_slot)
576 543 : ExecClearTuple(fs->func_slot);
577 : }
578 :
579 38925 : ExecScanReScan(&node->ss);
580 :
581 : /*
582 : * Here we have a choice whether to drop the tuplestores (and recompute
583 : * the function outputs) or just rescan them. We must recompute if an
584 : * expression contains changed parameters, else we rescan.
585 : *
586 : * XXX maybe we should recompute if the function is volatile? But in
587 : * general the executor doesn't conditionalize its actions on that.
588 : */
589 38925 : if (chgparam)
590 : {
591 : ListCell *lc;
592 :
593 37055 : i = 0;
594 74152 : foreach(lc, scan->functions)
595 : {
596 37097 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
597 :
598 37097 : if (bms_overlap(chgparam, rtfunc->funcparams))
599 : {
600 35853 : if (node->funcstates[i].tstore != NULL)
601 : {
602 31616 : tuplestore_end(node->funcstates[i].tstore);
603 31616 : node->funcstates[i].tstore = NULL;
604 : }
605 35853 : node->funcstates[i].rowcount = -1;
606 : }
607 37097 : i++;
608 : }
609 : }
610 :
611 : /* Reset ordinality counter */
612 38925 : node->ordinal = 0;
613 :
614 : /* Make sure we rewind any remaining tuplestores */
615 77904 : for (i = 0; i < node->nfuncs; i++)
616 : {
617 38979 : if (node->funcstates[i].tstore != NULL)
618 2847 : tuplestore_rescan(node->funcstates[i].tstore);
619 : }
620 38925 : }
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