Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeFunctionscan.c
4 : * Support routines for scanning RangeFunctions (functions in rangetable).
5 : *
6 : * Portions Copyright (c) 1996-2017, 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 682958 : 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 682958 : estate = node->ss.ps.state;
74 682958 : direction = estate->es_direction;
75 682958 : scanslot = node->ss.ss_ScanTupleSlot;
76 :
77 682958 : 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 682242 : 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 682242 : if (tstore == NULL)
93 : {
94 24774 : node->funcstates[0].tstore = tstore =
95 24774 : ExecMakeTableFunctionResult(node->funcstates[0].setexpr,
96 : node->ss.ps.ps_ExprContext,
97 : node->argcontext,
98 12387 : node->funcstates[0].tupdesc,
99 12387 : 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 12313 : tuplestore_rescan(tstore);
107 : }
108 :
109 : /*
110 : * Get the next tuple from tuplestore.
111 : */
112 682168 : (void) tuplestore_gettupleslot(tstore,
113 : ScanDirectionIsForward(direction),
114 : false,
115 : scanslot);
116 682168 : 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 : */
125 716 : oldpos = node->ordinal;
126 716 : if (ScanDirectionIsForward(direction))
127 706 : node->ordinal++;
128 : else
129 10 : 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 : */
138 716 : ExecClearTuple(scanslot);
139 716 : att = 0;
140 716 : alldone = true;
141 1631 : for (funcno = 0; funcno < node->nfuncs; funcno++)
142 : {
143 915 : 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 : */
151 915 : if (fs->tstore == NULL)
152 : {
153 196 : fs->tstore =
154 196 : ExecMakeTableFunctionResult(fs->setexpr,
155 : node->ss.ps.ps_ExprContext,
156 : node->argcontext,
157 : fs->tupdesc,
158 196 : 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 : */
165 196 : 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 : */
175 915 : if (fs->rowcount != -1 && fs->rowcount < oldpos)
176 12 : ExecClearTuple(fs->func_slot);
177 : else
178 903 : (void) tuplestore_gettupleslot(fs->tstore,
179 : ScanDirectionIsForward(direction),
180 : false,
181 : fs->func_slot);
182 :
183 1169 : 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 : */
192 254 : if (ScanDirectionIsForward(direction) && fs->rowcount == -1)
193 192 : fs->rowcount = node->ordinal;
194 :
195 : /*
196 : * populate the result cols with nulls
197 : */
198 672 : for (i = 0; i < fs->colcount; i++)
199 : {
200 418 : scanslot->tts_values[att] = (Datum) 0;
201 418 : scanslot->tts_isnull[att] = true;
202 418 : att++;
203 : }
204 : }
205 : else
206 : {
207 : /*
208 : * we have a result, so just copy it to the result cols.
209 : */
210 661 : slot_getallattrs(fs->func_slot);
211 :
212 1595 : for (i = 0; i < fs->colcount; i++)
213 : {
214 934 : scanslot->tts_values[att] = fs->func_slot->tts_values[i];
215 934 : scanslot->tts_isnull[att] = fs->func_slot->tts_isnull[i];
216 934 : 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 : */
223 661 : alldone = false;
224 : }
225 : }
226 :
227 : /*
228 : * ordinal col is always last, per spec.
229 : */
230 716 : if (node->ordinality)
231 : {
232 659 : scanslot->tts_values[att] = Int64GetDatumFast(node->ordinal);
233 659 : 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 : */
240 716 : if (!alldone)
241 562 : ExecStoreVirtualTuple(scanslot);
242 :
243 716 : 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 680669 : ExecFunctionScan(PlanState *pstate)
267 : {
268 680669 : FunctionScanState *node = castNode(FunctionScanState, pstate);
269 :
270 680669 : return ExecScan(&node->ss,
271 : (ExecScanAccessMtd) FunctionNext,
272 : (ExecScanRecheckMtd) FunctionRecheck);
273 : }
274 :
275 : /* ----------------------------------------------------------------
276 : * ExecInitFunctionScan
277 : * ----------------------------------------------------------------
278 : */
279 : FunctionScanState *
280 1468 : ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
281 : {
282 : FunctionScanState *scanstate;
283 1468 : 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 1468 : Assert(!(eflags & EXEC_FLAG_MARK));
291 :
292 : /*
293 : * FunctionScan should not have any children.
294 : */
295 1468 : Assert(outerPlan(node) == NULL);
296 1468 : Assert(innerPlan(node) == NULL);
297 :
298 : /*
299 : * create new ScanState for node
300 : */
301 1468 : scanstate = makeNode(FunctionScanState);
302 1468 : scanstate->ss.ps.plan = (Plan *) node;
303 1468 : scanstate->ss.ps.state = estate;
304 1468 : scanstate->ss.ps.ExecProcNode = ExecFunctionScan;
305 1468 : scanstate->eflags = eflags;
306 :
307 : /*
308 : * are we adding an ordinality column?
309 : */
310 1468 : scanstate->ordinality = node->funcordinality;
311 :
312 1468 : scanstate->nfuncs = nfuncs;
313 1468 : if (nfuncs == 1 && !node->funcordinality)
314 1397 : scanstate->simple = true;
315 : else
316 71 : 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 1468 : scanstate->ordinal = 0;
329 :
330 : /*
331 : * Miscellaneous initialization
332 : *
333 : * create expression context for node
334 : */
335 1468 : ExecAssignExprContext(estate, &scanstate->ss.ps);
336 :
337 : /*
338 : * tuple table initialization
339 : */
340 1468 : ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
341 1468 : ExecInitScanTupleSlot(estate, &scanstate->ss);
342 :
343 : /*
344 : * initialize child expressions
345 : */
346 1468 : scanstate->ss.ps.qual =
347 1468 : ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
348 :
349 1468 : scanstate->funcstates = palloc(nfuncs * sizeof(FunctionScanPerFuncState));
350 :
351 1468 : natts = 0;
352 1468 : i = 0;
353 2982 : foreach(lc, node->functions)
354 : {
355 1514 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
356 1514 : Node *funcexpr = rtfunc->funcexpr;
357 1514 : int colcount = rtfunc->funccolcount;
358 1514 : FunctionScanPerFuncState *fs = &scanstate->funcstates[i];
359 : TypeFuncClass functypclass;
360 : Oid funcrettype;
361 : TupleDesc tupdesc;
362 :
363 1514 : fs->setexpr =
364 1514 : ExecInitTableFunctionResult((Expr *) funcexpr,
365 : scanstate->ss.ps.ps_ExprContext,
366 : &scanstate->ss.ps);
367 :
368 : /*
369 : * Don't allocate the tuplestores; the actual calls to the functions
370 : * do that. NULL means that we have not called the function yet (or
371 : * need to call it again after a rescan).
372 : */
373 1514 : fs->tstore = NULL;
374 1514 : fs->rowcount = -1;
375 :
376 : /*
377 : * Now determine if the function returns a simple or composite type,
378 : * and build an appropriate tupdesc. Note that in the composite case,
379 : * the function may now return more columns than it did when the plan
380 : * was made; we have to ignore any columns beyond "colcount".
381 : */
382 1514 : functypclass = get_expr_result_type(funcexpr,
383 : &funcrettype,
384 : &tupdesc);
385 :
386 1514 : if (functypclass == TYPEFUNC_COMPOSITE)
387 : {
388 : /* Composite data type, e.g. a table's row type */
389 587 : Assert(tupdesc);
390 587 : Assert(tupdesc->natts >= colcount);
391 : /* Must copy it out of typcache for safety */
392 587 : tupdesc = CreateTupleDescCopy(tupdesc);
393 : }
394 927 : else if (functypclass == TYPEFUNC_SCALAR)
395 : {
396 : /* Base data type, i.e. scalar */
397 880 : tupdesc = CreateTemplateTupleDesc(1, false);
398 880 : TupleDescInitEntry(tupdesc,
399 : (AttrNumber) 1,
400 : NULL, /* don't care about the name here */
401 : funcrettype,
402 : -1,
403 : 0);
404 880 : TupleDescInitEntryCollation(tupdesc,
405 : (AttrNumber) 1,
406 : exprCollation(funcexpr));
407 : }
408 47 : else if (functypclass == TYPEFUNC_RECORD)
409 : {
410 47 : tupdesc = BuildDescFromLists(rtfunc->funccolnames,
411 : rtfunc->funccoltypes,
412 : rtfunc->funccoltypmods,
413 : rtfunc->funccolcollations);
414 :
415 : /*
416 : * For RECORD results, make sure a typmod has been assigned. (The
417 : * function should do this for itself, but let's cover things in
418 : * case it doesn't.)
419 : */
420 47 : BlessTupleDesc(tupdesc);
421 : }
422 : else
423 : {
424 : /* crummy error message, but parser should have caught this */
425 0 : elog(ERROR, "function in FROM has unsupported return type");
426 : }
427 :
428 1514 : fs->tupdesc = tupdesc;
429 1514 : fs->colcount = colcount;
430 :
431 : /*
432 : * We only need separate slots for the function results if we are
433 : * doing ordinality or multiple functions; otherwise, we'll fetch
434 : * function results directly into the scan slot.
435 : */
436 1514 : if (!scanstate->simple)
437 : {
438 117 : fs->func_slot = ExecInitExtraTupleSlot(estate);
439 117 : ExecSetSlotDescriptor(fs->func_slot, fs->tupdesc);
440 : }
441 : else
442 1397 : fs->func_slot = NULL;
443 :
444 1514 : natts += colcount;
445 1514 : i++;
446 : }
447 :
448 : /*
449 : * Create the combined TupleDesc
450 : *
451 : * If there is just one function without ordinality, the scan result
452 : * tupdesc is the same as the function result tupdesc --- except that we
453 : * may stuff new names into it below, so drop any rowtype label.
454 : */
455 1468 : if (scanstate->simple)
456 : {
457 1397 : scan_tupdesc = CreateTupleDescCopy(scanstate->funcstates[0].tupdesc);
458 1397 : scan_tupdesc->tdtypeid = RECORDOID;
459 1397 : scan_tupdesc->tdtypmod = -1;
460 : }
461 : else
462 : {
463 71 : AttrNumber attno = 0;
464 :
465 71 : if (node->funcordinality)
466 63 : natts++;
467 :
468 71 : scan_tupdesc = CreateTemplateTupleDesc(natts, false);
469 :
470 188 : for (i = 0; i < nfuncs; i++)
471 : {
472 117 : TupleDesc tupdesc = scanstate->funcstates[i].tupdesc;
473 117 : int colcount = scanstate->funcstates[i].colcount;
474 : int j;
475 :
476 340 : for (j = 1; j <= colcount; j++)
477 223 : TupleDescCopyEntry(scan_tupdesc, ++attno, tupdesc, j);
478 : }
479 :
480 : /* If doing ordinality, add a column of type "bigint" at the end */
481 71 : if (node->funcordinality)
482 : {
483 63 : TupleDescInitEntry(scan_tupdesc,
484 : ++attno,
485 : NULL, /* don't care about the name here */
486 : INT8OID,
487 : -1,
488 : 0);
489 : }
490 :
491 71 : Assert(attno == natts);
492 : }
493 :
494 1468 : ExecAssignScanType(&scanstate->ss, scan_tupdesc);
495 :
496 : /*
497 : * Initialize result tuple type and projection info.
498 : */
499 1468 : ExecAssignResultTypeFromTL(&scanstate->ss.ps);
500 1468 : ExecAssignScanProjectionInfo(&scanstate->ss);
501 :
502 : /*
503 : * Create a memory context that ExecMakeTableFunctionResult can use to
504 : * evaluate function arguments in. We can't use the per-tuple context for
505 : * this because it gets reset too often; but we don't want to leak
506 : * evaluation results into the query-lifespan context either. We just
507 : * need one context, because we evaluate each function separately.
508 : */
509 1468 : scanstate->argcontext = AllocSetContextCreate(CurrentMemoryContext,
510 : "Table function arguments",
511 : ALLOCSET_DEFAULT_SIZES);
512 :
513 1468 : return scanstate;
514 : }
515 :
516 : /* ----------------------------------------------------------------
517 : * ExecEndFunctionScan
518 : *
519 : * frees any storage allocated through C routines.
520 : * ----------------------------------------------------------------
521 : */
522 : void
523 1385 : ExecEndFunctionScan(FunctionScanState *node)
524 : {
525 : int i;
526 :
527 : /*
528 : * Free the exprcontext
529 : */
530 1385 : ExecFreeExprContext(&node->ss.ps);
531 :
532 : /*
533 : * clean out the tuple table
534 : */
535 1385 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
536 1385 : ExecClearTuple(node->ss.ss_ScanTupleSlot);
537 :
538 : /*
539 : * Release slots and tuplestore resources
540 : */
541 2814 : for (i = 0; i < node->nfuncs; i++)
542 : {
543 1429 : FunctionScanPerFuncState *fs = &node->funcstates[i];
544 :
545 1429 : if (fs->func_slot)
546 113 : ExecClearTuple(fs->func_slot);
547 :
548 1429 : if (fs->tstore != NULL)
549 : {
550 1202 : tuplestore_end(node->funcstates[i].tstore);
551 1202 : fs->tstore = NULL;
552 : }
553 : }
554 1385 : }
555 :
556 : /* ----------------------------------------------------------------
557 : * ExecReScanFunctionScan
558 : *
559 : * Rescans the relation.
560 : * ----------------------------------------------------------------
561 : */
562 : void
563 11721 : ExecReScanFunctionScan(FunctionScanState *node)
564 : {
565 11721 : FunctionScan *scan = (FunctionScan *) node->ss.ps.plan;
566 : int i;
567 11721 : Bitmapset *chgparam = node->ss.ps.chgParam;
568 :
569 11721 : ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
570 23460 : for (i = 0; i < node->nfuncs; i++)
571 : {
572 11739 : FunctionScanPerFuncState *fs = &node->funcstates[i];
573 :
574 11739 : if (fs->func_slot)
575 121 : ExecClearTuple(fs->func_slot);
576 : }
577 :
578 11721 : ExecScanReScan(&node->ss);
579 :
580 : /*
581 : * Here we have a choice whether to drop the tuplestores (and recompute
582 : * the function outputs) or just rescan them. We must recompute if an
583 : * expression contains changed parameters, else we rescan.
584 : *
585 : * XXX maybe we should recompute if the function is volatile? But in
586 : * general the executor doesn't conditionalize its actions on that.
587 : */
588 11721 : if (chgparam)
589 : {
590 : ListCell *lc;
591 :
592 11540 : i = 0;
593 23094 : foreach(lc, scan->functions)
594 : {
595 11554 : RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc);
596 :
597 11554 : if (bms_overlap(chgparam, rtfunc->funcparams))
598 : {
599 11539 : if (node->funcstates[i].tstore != NULL)
600 : {
601 11296 : tuplestore_end(node->funcstates[i].tstore);
602 11296 : node->funcstates[i].tstore = NULL;
603 : }
604 11539 : node->funcstates[i].rowcount = -1;
605 : }
606 11554 : i++;
607 : }
608 : }
609 :
610 : /* Reset ordinality counter */
611 11721 : node->ordinal = 0;
612 :
613 : /* Make sure we rewind any remaining tuplestores */
614 23460 : for (i = 0; i < node->nfuncs; i++)
615 : {
616 11739 : if (node->funcstates[i].tstore != NULL)
617 175 : tuplestore_rescan(node->funcstates[i].tstore);
618 : }
619 11721 : }
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