Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeIndexonlyscan.c
4 : * Routines to support index-only scans
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/nodeIndexonlyscan.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : /*
16 : * INTERFACE ROUTINES
17 : * ExecIndexOnlyScan scans an index
18 : * IndexOnlyNext retrieve next tuple
19 : * ExecInitIndexOnlyScan creates and initializes state info.
20 : * ExecReScanIndexOnlyScan rescans the indexed relation.
21 : * ExecEndIndexOnlyScan releases all storage.
22 : * ExecIndexOnlyMarkPos marks scan position.
23 : * ExecIndexOnlyRestrPos restores scan position.
24 : * ExecIndexOnlyScanEstimate estimates DSM space needed for
25 : * parallel index-only scan
26 : * ExecIndexOnlyScanInitializeDSM initialize DSM for parallel
27 : * index-only scan
28 : * ExecIndexOnlyScanReInitializeDSM reinitialize DSM for fresh scan
29 : * ExecIndexOnlyScanInitializeWorker attach to DSM info in parallel worker
30 : */
31 : #include "postgres.h"
32 :
33 : #include "access/genam.h"
34 : #include "access/relscan.h"
35 : #include "access/tableam.h"
36 : #include "access/tupdesc.h"
37 : #include "access/visibilitymap.h"
38 : #include "executor/execdebug.h"
39 : #include "executor/nodeIndexonlyscan.h"
40 : #include "executor/nodeIndexscan.h"
41 : #include "miscadmin.h"
42 : #include "storage/bufmgr.h"
43 : #include "storage/predicate.h"
44 : #include "utils/memutils.h"
45 : #include "utils/rel.h"
46 :
47 :
48 : static TupleTableSlot *IndexOnlyNext(IndexOnlyScanState *node);
49 : static void StoreIndexTuple(TupleTableSlot *slot, IndexTuple itup,
50 : TupleDesc itupdesc);
51 :
52 :
53 : /* ----------------------------------------------------------------
54 : * IndexOnlyNext
55 : *
56 : * Retrieve a tuple from the IndexOnlyScan node's index.
57 : * ----------------------------------------------------------------
58 : */
59 : static TupleTableSlot *
60 5098968 : IndexOnlyNext(IndexOnlyScanState *node)
61 : {
62 : EState *estate;
63 : ExprContext *econtext;
64 : ScanDirection direction;
65 : IndexScanDesc scandesc;
66 : TupleTableSlot *slot;
67 : ItemPointer tid;
68 :
69 : /*
70 : * extract necessary information from index scan node
71 : */
72 5098968 : estate = node->ss.ps.state;
73 :
74 : /*
75 : * Determine which direction to scan the index in based on the plan's scan
76 : * direction and the current direction of execution.
77 : */
78 5098968 : direction = ScanDirectionCombine(estate->es_direction,
79 : ((IndexOnlyScan *) node->ss.ps.plan)->indexorderdir);
80 5098968 : scandesc = node->ioss_ScanDesc;
81 5098968 : econtext = node->ss.ps.ps_ExprContext;
82 5098968 : slot = node->ss.ss_ScanTupleSlot;
83 :
84 5098968 : if (scandesc == NULL)
85 : {
86 : /*
87 : * We reach here if the index only scan is not parallel, or if we're
88 : * serially executing an index only scan that was planned to be
89 : * parallel.
90 : */
91 9512 : scandesc = index_beginscan(node->ss.ss_currentRelation,
92 : node->ioss_RelationDesc,
93 : estate->es_snapshot,
94 : node->ioss_NumScanKeys,
95 : node->ioss_NumOrderByKeys);
96 :
97 9512 : node->ioss_ScanDesc = scandesc;
98 :
99 :
100 : /* Set it up for index-only scan */
101 9512 : node->ioss_ScanDesc->xs_want_itup = true;
102 9512 : node->ioss_VMBuffer = InvalidBuffer;
103 :
104 : /*
105 : * If no run-time keys to calculate or they are ready, go ahead and
106 : * pass the scankeys to the index AM.
107 : */
108 9512 : if (node->ioss_NumRuntimeKeys == 0 || node->ioss_RuntimeKeysReady)
109 9512 : index_rescan(scandesc,
110 9512 : node->ioss_ScanKeys,
111 : node->ioss_NumScanKeys,
112 9512 : node->ioss_OrderByKeys,
113 : node->ioss_NumOrderByKeys);
114 : }
115 :
116 : /*
117 : * OK, now that we have what we need, fetch the next tuple.
118 : */
119 5231846 : while ((tid = index_getnext_tid(scandesc, direction)) != NULL)
120 : {
121 5151714 : bool tuple_from_heap = false;
122 :
123 5151714 : CHECK_FOR_INTERRUPTS();
124 :
125 : /*
126 : * We can skip the heap fetch if the TID references a heap page on
127 : * which all tuples are known visible to everybody. In any case,
128 : * we'll use the index tuple not the heap tuple as the data source.
129 : *
130 : * Note on Memory Ordering Effects: visibilitymap_get_status does not
131 : * lock the visibility map buffer, and therefore the result we read
132 : * here could be slightly stale. However, it can't be stale enough to
133 : * matter.
134 : *
135 : * We need to detect clearing a VM bit due to an insert right away,
136 : * because the tuple is present in the index page but not visible. The
137 : * reading of the TID by this scan (using a shared lock on the index
138 : * buffer) is serialized with the insert of the TID into the index
139 : * (using an exclusive lock on the index buffer). Because the VM bit
140 : * is cleared before updating the index, and locking/unlocking of the
141 : * index page acts as a full memory barrier, we are sure to see the
142 : * cleared bit if we see a recently-inserted TID.
143 : *
144 : * Deletes do not update the index page (only VACUUM will clear out
145 : * the TID), so the clearing of the VM bit by a delete is not
146 : * serialized with this test below, and we may see a value that is
147 : * significantly stale. However, we don't care about the delete right
148 : * away, because the tuple is still visible until the deleting
149 : * transaction commits or the statement ends (if it's our
150 : * transaction). In either case, the lock on the VM buffer will have
151 : * been released (acting as a write barrier) after clearing the bit.
152 : * And for us to have a snapshot that includes the deleting
153 : * transaction (making the tuple invisible), we must have acquired
154 : * ProcArrayLock after that time, acting as a read barrier.
155 : *
156 : * It's worth going through this complexity to avoid needing to lock
157 : * the VM buffer, which could cause significant contention.
158 : */
159 5151714 : if (!VM_ALL_VISIBLE(scandesc->heapRelation,
160 : ItemPointerGetBlockNumber(tid),
161 : &node->ioss_VMBuffer))
162 : {
163 : /*
164 : * Rats, we have to visit the heap to check visibility.
165 : */
166 1991120 : InstrCountTuples2(node, 1);
167 1991120 : if (!index_fetch_heap(scandesc, node->ioss_TableSlot))
168 132872 : continue; /* no visible tuple, try next index entry */
169 :
170 1858248 : ExecClearTuple(node->ioss_TableSlot);
171 :
172 : /*
173 : * Only MVCC snapshots are supported here, so there should be no
174 : * need to keep following the HOT chain once a visible entry has
175 : * been found. If we did want to allow that, we'd need to keep
176 : * more state to remember not to call index_getnext_tid next time.
177 : */
178 1858248 : if (scandesc->xs_heap_continue)
179 0 : elog(ERROR, "non-MVCC snapshots are not supported in index-only scans");
180 :
181 : /*
182 : * Note: at this point we are holding a pin on the heap page, as
183 : * recorded in scandesc->xs_cbuf. We could release that pin now,
184 : * but it's not clear whether it's a win to do so. The next index
185 : * entry might require a visit to the same heap page.
186 : */
187 :
188 1858248 : tuple_from_heap = true;
189 : }
190 :
191 : /*
192 : * Fill the scan tuple slot with data from the index. This might be
193 : * provided in either HeapTuple or IndexTuple format. Conceivably an
194 : * index AM might fill both fields, in which case we prefer the heap
195 : * format, since it's probably a bit cheaper to fill a slot from.
196 : */
197 5018842 : if (scandesc->xs_hitup)
198 : {
199 : /*
200 : * We don't take the trouble to verify that the provided tuple has
201 : * exactly the slot's format, but it seems worth doing a quick
202 : * check on the number of fields.
203 : */
204 : Assert(slot->tts_tupleDescriptor->natts ==
205 : scandesc->xs_hitupdesc->natts);
206 1437684 : ExecForceStoreHeapTuple(scandesc->xs_hitup, slot, false);
207 : }
208 3581158 : else if (scandesc->xs_itup)
209 3581158 : StoreIndexTuple(slot, scandesc->xs_itup, scandesc->xs_itupdesc);
210 : else
211 0 : elog(ERROR, "no data returned for index-only scan");
212 :
213 : /*
214 : * If the index was lossy, we have to recheck the index quals.
215 : */
216 5018842 : if (scandesc->xs_recheck)
217 : {
218 14 : econtext->ecxt_scantuple = slot;
219 14 : if (!ExecQualAndReset(node->recheckqual, econtext))
220 : {
221 : /* Fails recheck, so drop it and loop back for another */
222 6 : InstrCountFiltered2(node, 1);
223 6 : continue;
224 : }
225 : }
226 :
227 : /*
228 : * We don't currently support rechecking ORDER BY distances. (In
229 : * principle, if the index can support retrieval of the originally
230 : * indexed value, it should be able to produce an exact distance
231 : * calculation too. So it's not clear that adding code here for
232 : * recheck/re-sort would be worth the trouble. But we should at least
233 : * throw an error if someone tries it.)
234 : */
235 5018836 : if (scandesc->numberOfOrderBys > 0 && scandesc->xs_recheckorderby)
236 6 : ereport(ERROR,
237 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
238 : errmsg("lossy distance functions are not supported in index-only scans")));
239 :
240 : /*
241 : * If we didn't access the heap, then we'll need to take a predicate
242 : * lock explicitly, as if we had. For now we do that at page level.
243 : */
244 5018830 : if (!tuple_from_heap)
245 3160594 : PredicateLockPage(scandesc->heapRelation,
246 : ItemPointerGetBlockNumber(tid),
247 : estate->es_snapshot);
248 :
249 5018830 : return slot;
250 : }
251 :
252 : /*
253 : * if we get here it means the index scan failed so we are at the end of
254 : * the scan..
255 : */
256 80132 : return ExecClearTuple(slot);
257 : }
258 :
259 : /*
260 : * StoreIndexTuple
261 : * Fill the slot with data from the index tuple.
262 : *
263 : * At some point this might be generally-useful functionality, but
264 : * right now we don't need it elsewhere.
265 : */
266 : static void
267 3581158 : StoreIndexTuple(TupleTableSlot *slot, IndexTuple itup, TupleDesc itupdesc)
268 : {
269 : /*
270 : * Note: we must use the tupdesc supplied by the AM in index_deform_tuple,
271 : * not the slot's tupdesc, in case the latter has different datatypes
272 : * (this happens for btree name_ops in particular). They'd better have
273 : * the same number of columns though, as well as being datatype-compatible
274 : * which is something we can't so easily check.
275 : */
276 : Assert(slot->tts_tupleDescriptor->natts == itupdesc->natts);
277 :
278 3581158 : ExecClearTuple(slot);
279 3581158 : index_deform_tuple(itup, itupdesc, slot->tts_values, slot->tts_isnull);
280 3581158 : ExecStoreVirtualTuple(slot);
281 3581158 : }
282 :
283 : /*
284 : * IndexOnlyRecheck -- access method routine to recheck a tuple in EvalPlanQual
285 : *
286 : * This can't really happen, since an index can't supply CTID which would
287 : * be necessary data for any potential EvalPlanQual target relation. If it
288 : * did happen, the EPQ code would pass us the wrong data, namely a heap
289 : * tuple not an index tuple. So throw an error.
290 : */
291 : static bool
292 0 : IndexOnlyRecheck(IndexOnlyScanState *node, TupleTableSlot *slot)
293 : {
294 0 : elog(ERROR, "EvalPlanQual recheck is not supported in index-only scans");
295 : return false; /* keep compiler quiet */
296 : }
297 :
298 : /* ----------------------------------------------------------------
299 : * ExecIndexOnlyScan(node)
300 : * ----------------------------------------------------------------
301 : */
302 : static TupleTableSlot *
303 5098620 : ExecIndexOnlyScan(PlanState *pstate)
304 : {
305 5098620 : IndexOnlyScanState *node = castNode(IndexOnlyScanState, pstate);
306 :
307 : /*
308 : * If we have runtime keys and they've not already been set up, do it now.
309 : */
310 5098620 : if (node->ioss_NumRuntimeKeys != 0 && !node->ioss_RuntimeKeysReady)
311 552 : ExecReScan((PlanState *) node);
312 :
313 5098620 : return ExecScan(&node->ss,
314 : (ExecScanAccessMtd) IndexOnlyNext,
315 : (ExecScanRecheckMtd) IndexOnlyRecheck);
316 : }
317 :
318 : /* ----------------------------------------------------------------
319 : * ExecReScanIndexOnlyScan(node)
320 : *
321 : * Recalculates the values of any scan keys whose value depends on
322 : * information known at runtime, then rescans the indexed relation.
323 : *
324 : * Updating the scan key was formerly done separately in
325 : * ExecUpdateIndexScanKeys. Integrating it into ReScan makes
326 : * rescans of indices and relations/general streams more uniform.
327 : * ----------------------------------------------------------------
328 : */
329 : void
330 83522 : ExecReScanIndexOnlyScan(IndexOnlyScanState *node)
331 : {
332 : /*
333 : * If we are doing runtime key calculations (ie, any of the index key
334 : * values weren't simple Consts), compute the new key values. But first,
335 : * reset the context so we don't leak memory as each outer tuple is
336 : * scanned. Note this assumes that we will recalculate *all* runtime keys
337 : * on each call.
338 : */
339 83522 : if (node->ioss_NumRuntimeKeys != 0)
340 : {
341 83354 : ExprContext *econtext = node->ioss_RuntimeContext;
342 :
343 83354 : ResetExprContext(econtext);
344 83354 : ExecIndexEvalRuntimeKeys(econtext,
345 : node->ioss_RuntimeKeys,
346 : node->ioss_NumRuntimeKeys);
347 : }
348 83522 : node->ioss_RuntimeKeysReady = true;
349 :
350 : /* reset index scan */
351 83522 : if (node->ioss_ScanDesc)
352 81910 : index_rescan(node->ioss_ScanDesc,
353 81910 : node->ioss_ScanKeys, node->ioss_NumScanKeys,
354 81910 : node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
355 :
356 83522 : ExecScanReScan(&node->ss);
357 83522 : }
358 :
359 :
360 : /* ----------------------------------------------------------------
361 : * ExecEndIndexOnlyScan
362 : * ----------------------------------------------------------------
363 : */
364 : void
365 14664 : ExecEndIndexOnlyScan(IndexOnlyScanState *node)
366 : {
367 : Relation indexRelationDesc;
368 : IndexScanDesc indexScanDesc;
369 :
370 : /*
371 : * extract information from the node
372 : */
373 14664 : indexRelationDesc = node->ioss_RelationDesc;
374 14664 : indexScanDesc = node->ioss_ScanDesc;
375 :
376 : /* Release VM buffer pin, if any. */
377 14664 : if (node->ioss_VMBuffer != InvalidBuffer)
378 : {
379 5842 : ReleaseBuffer(node->ioss_VMBuffer);
380 5842 : node->ioss_VMBuffer = InvalidBuffer;
381 : }
382 :
383 : /*
384 : * close the index relation (no-op if we didn't open it)
385 : */
386 14664 : if (indexScanDesc)
387 9628 : index_endscan(indexScanDesc);
388 14664 : if (indexRelationDesc)
389 12566 : index_close(indexRelationDesc, NoLock);
390 14664 : }
391 :
392 : /* ----------------------------------------------------------------
393 : * ExecIndexOnlyMarkPos
394 : *
395 : * Note: we assume that no caller attempts to set a mark before having read
396 : * at least one tuple. Otherwise, ioss_ScanDesc might still be NULL.
397 : * ----------------------------------------------------------------
398 : */
399 : void
400 124010 : ExecIndexOnlyMarkPos(IndexOnlyScanState *node)
401 : {
402 124010 : EState *estate = node->ss.ps.state;
403 124010 : EPQState *epqstate = estate->es_epq_active;
404 :
405 124010 : if (epqstate != NULL)
406 : {
407 : /*
408 : * We are inside an EvalPlanQual recheck. If a test tuple exists for
409 : * this relation, then we shouldn't access the index at all. We would
410 : * instead need to save, and later restore, the state of the
411 : * relsubs_done flag, so that re-fetching the test tuple is possible.
412 : * However, given the assumption that no caller sets a mark at the
413 : * start of the scan, we can only get here with relsubs_done[i]
414 : * already set, and so no state need be saved.
415 : */
416 0 : Index scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
417 :
418 : Assert(scanrelid > 0);
419 0 : if (epqstate->relsubs_slot[scanrelid - 1] != NULL ||
420 0 : epqstate->relsubs_rowmark[scanrelid - 1] != NULL)
421 : {
422 : /* Verify the claim above */
423 0 : if (!epqstate->relsubs_done[scanrelid - 1])
424 0 : elog(ERROR, "unexpected ExecIndexOnlyMarkPos call in EPQ recheck");
425 0 : return;
426 : }
427 : }
428 :
429 124010 : index_markpos(node->ioss_ScanDesc);
430 : }
431 :
432 : /* ----------------------------------------------------------------
433 : * ExecIndexOnlyRestrPos
434 : * ----------------------------------------------------------------
435 : */
436 : void
437 6 : ExecIndexOnlyRestrPos(IndexOnlyScanState *node)
438 : {
439 6 : EState *estate = node->ss.ps.state;
440 6 : EPQState *epqstate = estate->es_epq_active;
441 :
442 6 : if (estate->es_epq_active != NULL)
443 : {
444 : /* See comments in ExecIndexMarkPos */
445 0 : Index scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
446 :
447 : Assert(scanrelid > 0);
448 0 : if (epqstate->relsubs_slot[scanrelid - 1] != NULL ||
449 0 : epqstate->relsubs_rowmark[scanrelid - 1] != NULL)
450 : {
451 : /* Verify the claim above */
452 0 : if (!epqstate->relsubs_done[scanrelid - 1])
453 0 : elog(ERROR, "unexpected ExecIndexOnlyRestrPos call in EPQ recheck");
454 0 : return;
455 : }
456 : }
457 :
458 6 : index_restrpos(node->ioss_ScanDesc);
459 : }
460 :
461 : /* ----------------------------------------------------------------
462 : * ExecInitIndexOnlyScan
463 : *
464 : * Initializes the index scan's state information, creates
465 : * scan keys, and opens the base and index relations.
466 : *
467 : * Note: index scans have 2 sets of state information because
468 : * we have to keep track of the base relation and the
469 : * index relation.
470 : * ----------------------------------------------------------------
471 : */
472 : IndexOnlyScanState *
473 14788 : ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
474 : {
475 : IndexOnlyScanState *indexstate;
476 : Relation currentRelation;
477 : LOCKMODE lockmode;
478 : TupleDesc tupDesc;
479 :
480 : /*
481 : * create state structure
482 : */
483 14788 : indexstate = makeNode(IndexOnlyScanState);
484 14788 : indexstate->ss.ps.plan = (Plan *) node;
485 14788 : indexstate->ss.ps.state = estate;
486 14788 : indexstate->ss.ps.ExecProcNode = ExecIndexOnlyScan;
487 :
488 : /*
489 : * Miscellaneous initialization
490 : *
491 : * create expression context for node
492 : */
493 14788 : ExecAssignExprContext(estate, &indexstate->ss.ps);
494 :
495 : /*
496 : * open the scan relation
497 : */
498 14788 : currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
499 :
500 14788 : indexstate->ss.ss_currentRelation = currentRelation;
501 14788 : indexstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
502 :
503 : /*
504 : * Build the scan tuple type using the indextlist generated by the
505 : * planner. We use this, rather than the index's physical tuple
506 : * descriptor, because the latter contains storage column types not the
507 : * types of the original datums. (It's the AM's responsibility to return
508 : * suitable data anyway.)
509 : */
510 14788 : tupDesc = ExecTypeFromTL(node->indextlist);
511 14788 : ExecInitScanTupleSlot(estate, &indexstate->ss, tupDesc,
512 : &TTSOpsVirtual);
513 :
514 : /*
515 : * We need another slot, in a format that's suitable for the table AM, for
516 : * when we need to fetch a tuple from the table for rechecking visibility.
517 : */
518 14788 : indexstate->ioss_TableSlot =
519 14788 : ExecAllocTableSlot(&estate->es_tupleTable,
520 : RelationGetDescr(currentRelation),
521 : table_slot_callbacks(currentRelation));
522 :
523 : /*
524 : * Initialize result type and projection info. The node's targetlist will
525 : * contain Vars with varno = INDEX_VAR, referencing the scan tuple.
526 : */
527 14788 : ExecInitResultTypeTL(&indexstate->ss.ps);
528 14788 : ExecAssignScanProjectionInfoWithVarno(&indexstate->ss, INDEX_VAR);
529 :
530 : /*
531 : * initialize child expressions
532 : *
533 : * Note: we don't initialize all of the indexorderby expression, only the
534 : * sub-parts corresponding to runtime keys (see below).
535 : */
536 14788 : indexstate->ss.ps.qual =
537 14788 : ExecInitQual(node->scan.plan.qual, (PlanState *) indexstate);
538 14788 : indexstate->recheckqual =
539 14788 : ExecInitQual(node->recheckqual, (PlanState *) indexstate);
540 :
541 : /*
542 : * If we are just doing EXPLAIN (ie, aren't going to run the plan), stop
543 : * here. This allows an index-advisor plugin to EXPLAIN a plan containing
544 : * references to nonexistent indexes.
545 : */
546 14788 : if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
547 2098 : return indexstate;
548 :
549 : /* Open the index relation. */
550 12690 : lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
551 12690 : indexstate->ioss_RelationDesc = index_open(node->indexid, lockmode);
552 :
553 : /*
554 : * Initialize index-specific scan state
555 : */
556 12690 : indexstate->ioss_RuntimeKeysReady = false;
557 12690 : indexstate->ioss_RuntimeKeys = NULL;
558 12690 : indexstate->ioss_NumRuntimeKeys = 0;
559 :
560 : /*
561 : * build the index scan keys from the index qualification
562 : */
563 12690 : ExecIndexBuildScanKeys((PlanState *) indexstate,
564 : indexstate->ioss_RelationDesc,
565 : node->indexqual,
566 : false,
567 12690 : &indexstate->ioss_ScanKeys,
568 : &indexstate->ioss_NumScanKeys,
569 : &indexstate->ioss_RuntimeKeys,
570 : &indexstate->ioss_NumRuntimeKeys,
571 : NULL, /* no ArrayKeys */
572 : NULL);
573 :
574 : /*
575 : * any ORDER BY exprs have to be turned into scankeys in the same way
576 : */
577 12690 : ExecIndexBuildScanKeys((PlanState *) indexstate,
578 : indexstate->ioss_RelationDesc,
579 : node->indexorderby,
580 : true,
581 12690 : &indexstate->ioss_OrderByKeys,
582 : &indexstate->ioss_NumOrderByKeys,
583 : &indexstate->ioss_RuntimeKeys,
584 : &indexstate->ioss_NumRuntimeKeys,
585 : NULL, /* no ArrayKeys */
586 : NULL);
587 :
588 : /*
589 : * If we have runtime keys, we need an ExprContext to evaluate them. The
590 : * node's standard context won't do because we want to reset that context
591 : * for every tuple. So, build another context just like the other one...
592 : * -tgl 7/11/00
593 : */
594 12690 : if (indexstate->ioss_NumRuntimeKeys != 0)
595 : {
596 2090 : ExprContext *stdecontext = indexstate->ss.ps.ps_ExprContext;
597 :
598 2090 : ExecAssignExprContext(estate, &indexstate->ss.ps);
599 2090 : indexstate->ioss_RuntimeContext = indexstate->ss.ps.ps_ExprContext;
600 2090 : indexstate->ss.ps.ps_ExprContext = stdecontext;
601 : }
602 : else
603 : {
604 10600 : indexstate->ioss_RuntimeContext = NULL;
605 : }
606 :
607 : /*
608 : * all done.
609 : */
610 12690 : return indexstate;
611 : }
612 :
613 : /* ----------------------------------------------------------------
614 : * Parallel Index-only Scan Support
615 : * ----------------------------------------------------------------
616 : */
617 :
618 : /* ----------------------------------------------------------------
619 : * ExecIndexOnlyScanEstimate
620 : *
621 : * Compute the amount of space we'll need in the parallel
622 : * query DSM, and inform pcxt->estimator about our needs.
623 : * ----------------------------------------------------------------
624 : */
625 : void
626 40 : ExecIndexOnlyScanEstimate(IndexOnlyScanState *node,
627 : ParallelContext *pcxt)
628 : {
629 40 : EState *estate = node->ss.ps.state;
630 :
631 40 : node->ioss_PscanLen = index_parallelscan_estimate(node->ioss_RelationDesc,
632 : estate->es_snapshot);
633 40 : shm_toc_estimate_chunk(&pcxt->estimator, node->ioss_PscanLen);
634 40 : shm_toc_estimate_keys(&pcxt->estimator, 1);
635 40 : }
636 :
637 : /* ----------------------------------------------------------------
638 : * ExecIndexOnlyScanInitializeDSM
639 : *
640 : * Set up a parallel index-only scan descriptor.
641 : * ----------------------------------------------------------------
642 : */
643 : void
644 40 : ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node,
645 : ParallelContext *pcxt)
646 : {
647 40 : EState *estate = node->ss.ps.state;
648 : ParallelIndexScanDesc piscan;
649 :
650 40 : piscan = shm_toc_allocate(pcxt->toc, node->ioss_PscanLen);
651 40 : index_parallelscan_initialize(node->ss.ss_currentRelation,
652 : node->ioss_RelationDesc,
653 : estate->es_snapshot,
654 : piscan);
655 40 : shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, piscan);
656 40 : node->ioss_ScanDesc =
657 40 : index_beginscan_parallel(node->ss.ss_currentRelation,
658 : node->ioss_RelationDesc,
659 : node->ioss_NumScanKeys,
660 : node->ioss_NumOrderByKeys,
661 : piscan);
662 40 : node->ioss_ScanDesc->xs_want_itup = true;
663 40 : node->ioss_VMBuffer = InvalidBuffer;
664 :
665 : /*
666 : * If no run-time keys to calculate or they are ready, go ahead and pass
667 : * the scankeys to the index AM.
668 : */
669 40 : if (node->ioss_NumRuntimeKeys == 0 || node->ioss_RuntimeKeysReady)
670 40 : index_rescan(node->ioss_ScanDesc,
671 40 : node->ioss_ScanKeys, node->ioss_NumScanKeys,
672 40 : node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
673 40 : }
674 :
675 : /* ----------------------------------------------------------------
676 : * ExecIndexOnlyScanReInitializeDSM
677 : *
678 : * Reset shared state before beginning a fresh scan.
679 : * ----------------------------------------------------------------
680 : */
681 : void
682 12 : ExecIndexOnlyScanReInitializeDSM(IndexOnlyScanState *node,
683 : ParallelContext *pcxt)
684 : {
685 12 : index_parallelrescan(node->ioss_ScanDesc);
686 12 : }
687 :
688 : /* ----------------------------------------------------------------
689 : * ExecIndexOnlyScanInitializeWorker
690 : *
691 : * Copy relevant information from TOC into planstate.
692 : * ----------------------------------------------------------------
693 : */
694 : void
695 200 : ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node,
696 : ParallelWorkerContext *pwcxt)
697 : {
698 : ParallelIndexScanDesc piscan;
699 :
700 200 : piscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false);
701 200 : node->ioss_ScanDesc =
702 200 : index_beginscan_parallel(node->ss.ss_currentRelation,
703 : node->ioss_RelationDesc,
704 : node->ioss_NumScanKeys,
705 : node->ioss_NumOrderByKeys,
706 : piscan);
707 200 : node->ioss_ScanDesc->xs_want_itup = true;
708 :
709 : /*
710 : * If no run-time keys to calculate or they are ready, go ahead and pass
711 : * the scankeys to the index AM.
712 : */
713 200 : if (node->ioss_NumRuntimeKeys == 0 || node->ioss_RuntimeKeysReady)
714 200 : index_rescan(node->ioss_ScanDesc,
715 200 : node->ioss_ScanKeys, node->ioss_NumScanKeys,
716 200 : node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
717 200 : }
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