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Commit0414b26

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Add optimizer and executor support for parallel index-only scans.
Commit5262f7a added similar supportfor parallel index scans; this extends that work to index-only scans.As with parallel index scans, this requires support from the index AM,so currently parallel index-only scans will only be possible for btreeindexes.Rafia Sabih, reviewed and tested by Rahila Syed, Tushar Ahuja,and Amit KapilaDiscussion:http://postgr.es/m/CAOGQiiPEAs4C=TBp0XShxBvnWXuzGL2u++Hm1=qnCpd6_Mf8Fw@mail.gmail.com
1 parent16be2fd commit0414b26

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7 files changed

+191
-26
lines changed

7 files changed

+191
-26
lines changed

‎src/backend/executor/execParallel.c‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,7 @@
2929
#include"executor/nodeForeignscan.h"
3030
#include"executor/nodeSeqscan.h"
3131
#include"executor/nodeIndexscan.h"
32+
#include"executor/nodeIndexonlyscan.h"
3233
#include"executor/tqueue.h"
3334
#include"nodes/nodeFuncs.h"
3435
#include"optimizer/planmain.h"
@@ -202,6 +203,10 @@ ExecParallelEstimate(PlanState *planstate, ExecParallelEstimateContext *e)
202203
ExecIndexScanEstimate((IndexScanState*)planstate,
203204
e->pcxt);
204205
break;
206+
caseT_IndexOnlyScanState:
207+
ExecIndexOnlyScanEstimate((IndexOnlyScanState*)planstate,
208+
e->pcxt);
209+
break;
205210
caseT_ForeignScanState:
206211
ExecForeignScanEstimate((ForeignScanState*)planstate,
207212
e->pcxt);
@@ -258,6 +263,10 @@ ExecParallelInitializeDSM(PlanState *planstate,
258263
ExecIndexScanInitializeDSM((IndexScanState*)planstate,
259264
d->pcxt);
260265
break;
266+
caseT_IndexOnlyScanState:
267+
ExecIndexOnlyScanInitializeDSM((IndexOnlyScanState*)planstate,
268+
d->pcxt);
269+
break;
261270
caseT_ForeignScanState:
262271
ExecForeignScanInitializeDSM((ForeignScanState*)planstate,
263272
d->pcxt);
@@ -737,6 +746,9 @@ ExecParallelInitializeWorker(PlanState *planstate, shm_toc *toc)
737746
caseT_IndexScanState:
738747
ExecIndexScanInitializeWorker((IndexScanState*)planstate,toc);
739748
break;
749+
caseT_IndexOnlyScanState:
750+
ExecIndexOnlyScanInitializeWorker((IndexOnlyScanState*)planstate,toc);
751+
break;
740752
caseT_ForeignScanState:
741753
ExecForeignScanInitializeWorker((ForeignScanState*)planstate,
742754
toc);

‎src/backend/executor/nodeIndexonlyscan.c‎

Lines changed: 135 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,11 @@
2121
*ExecEndIndexOnlyScanreleases all storage.
2222
*ExecIndexOnlyMarkPosmarks scan position.
2323
*ExecIndexOnlyRestrPosrestores scan position.
24+
*ExecIndexOnlyScanEstimateestimates DSM space needed for
25+
*parallel index-only scan
26+
*ExecIndexOnlyScanInitializeDSMinitialize DSM for parallel
27+
*index-only scan
28+
*ExecIndexOnlyScanInitializeWorker attach to DSM info in parallel worker
2429
*/
2530
#include"postgres.h"
2631

@@ -277,6 +282,16 @@ ExecIndexOnlyScan(IndexOnlyScanState *node)
277282
void
278283
ExecReScanIndexOnlyScan(IndexOnlyScanState*node)
279284
{
285+
boolreset_parallel_scan= true;
286+
287+
/*
288+
* If we are here to just update the scan keys, then don't reset parallel
289+
* scan. For detailed reason behind this look in the comments for
290+
* ExecReScanIndexScan.
291+
*/
292+
if (node->ioss_NumRuntimeKeys!=0&& !node->ioss_RuntimeKeysReady)
293+
reset_parallel_scan= false;
294+
280295
/*
281296
* If we are doing runtime key calculations (ie, any of the index key
282297
* values weren't simple Consts), compute the new key values. But first,
@@ -296,10 +311,16 @@ ExecReScanIndexOnlyScan(IndexOnlyScanState *node)
296311
node->ioss_RuntimeKeysReady= true;
297312

298313
/* reset index scan */
299-
index_rescan(node->ioss_ScanDesc,
300-
node->ioss_ScanKeys,node->ioss_NumScanKeys,
301-
node->ioss_OrderByKeys,node->ioss_NumOrderByKeys);
314+
if (node->ioss_ScanDesc)
315+
{
316+
317+
index_rescan(node->ioss_ScanDesc,
318+
node->ioss_ScanKeys,node->ioss_NumScanKeys,
319+
node->ioss_OrderByKeys,node->ioss_NumOrderByKeys);
302320

321+
if (reset_parallel_scan&&node->ioss_ScanDesc->parallel_scan)
322+
index_parallelrescan(node->ioss_ScanDesc);
323+
}
303324
ExecScanReScan(&node->ss);
304325
}
305326

@@ -536,29 +557,124 @@ ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
536557
/*
537558
* Initialize scan descriptor.
538559
*/
539-
indexstate->ioss_ScanDesc=index_beginscan(currentRelation,
540-
indexstate->ioss_RelationDesc,
541-
estate->es_snapshot,
560+
if (!node->scan.plan.parallel_aware)
561+
{
562+
indexstate->ioss_ScanDesc=index_beginscan(currentRelation,
563+
indexstate->ioss_RelationDesc,
564+
estate->es_snapshot,
542565
indexstate->ioss_NumScanKeys,
543566
indexstate->ioss_NumOrderByKeys);
544567

545-
/* Set it up for index-only scan */
546-
indexstate->ioss_ScanDesc->xs_want_itup= true;
547-
indexstate->ioss_VMBuffer=InvalidBuffer;
548568

549-
/*
550-
* If no run-time keys to calculate, go ahead and pass the scankeys to the
551-
* index AM.
552-
*/
553-
if (indexstate->ioss_NumRuntimeKeys==0)
554-
index_rescan(indexstate->ioss_ScanDesc,
555-
indexstate->ioss_ScanKeys,
556-
indexstate->ioss_NumScanKeys,
557-
indexstate->ioss_OrderByKeys,
558-
indexstate->ioss_NumOrderByKeys);
569+
/* Set it up for index-only scan */
570+
indexstate->ioss_ScanDesc->xs_want_itup= true;
571+
indexstate->ioss_VMBuffer=InvalidBuffer;
572+
573+
/*
574+
* If no run-time keys to calculate, go ahead and pass the scankeys to
575+
* the index AM.
576+
*/
577+
if (indexstate->ioss_NumRuntimeKeys==0)
578+
index_rescan(indexstate->ioss_ScanDesc,
579+
indexstate->ioss_ScanKeys,
580+
indexstate->ioss_NumScanKeys,
581+
indexstate->ioss_OrderByKeys,
582+
indexstate->ioss_NumOrderByKeys);
583+
}
559584

560585
/*
561586
* all done.
562587
*/
563588
returnindexstate;
564589
}
590+
591+
/* ----------------------------------------------------------------
592+
*Parallel Index-only Scan Support
593+
* ----------------------------------------------------------------
594+
*/
595+
596+
/* ----------------------------------------------------------------
597+
*ExecIndexOnlyScanEstimate
598+
*
599+
*estimates the space required to serialize index-only scan node.
600+
* ----------------------------------------------------------------
601+
*/
602+
void
603+
ExecIndexOnlyScanEstimate(IndexOnlyScanState*node,
604+
ParallelContext*pcxt)
605+
{
606+
EState*estate=node->ss.ps.state;
607+
608+
node->ioss_PscanLen=index_parallelscan_estimate(node->ioss_RelationDesc,
609+
estate->es_snapshot);
610+
shm_toc_estimate_chunk(&pcxt->estimator,node->ioss_PscanLen);
611+
shm_toc_estimate_keys(&pcxt->estimator,1);
612+
}
613+
614+
/* ----------------------------------------------------------------
615+
*ExecIndexOnlyScanInitializeDSM
616+
*
617+
*Set up a parallel index-only scan descriptor.
618+
* ----------------------------------------------------------------
619+
*/
620+
void
621+
ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState*node,
622+
ParallelContext*pcxt)
623+
{
624+
EState*estate=node->ss.ps.state;
625+
ParallelIndexScanDescpiscan;
626+
627+
piscan=shm_toc_allocate(pcxt->toc,node->ioss_PscanLen);
628+
index_parallelscan_initialize(node->ss.ss_currentRelation,
629+
node->ioss_RelationDesc,
630+
estate->es_snapshot,
631+
piscan);
632+
shm_toc_insert(pcxt->toc,node->ss.ps.plan->plan_node_id,piscan);
633+
node->ioss_ScanDesc=
634+
index_beginscan_parallel(node->ss.ss_currentRelation,
635+
node->ioss_RelationDesc,
636+
node->ioss_NumScanKeys,
637+
node->ioss_NumOrderByKeys,
638+
piscan);
639+
node->ioss_ScanDesc->xs_want_itup= true;
640+
node->ioss_VMBuffer=InvalidBuffer;
641+
642+
/*
643+
* If no run-time keys to calculate, go ahead and pass the scankeys to
644+
* the index AM.
645+
*/
646+
if (node->ioss_NumRuntimeKeys==0)
647+
index_rescan(node->ioss_ScanDesc,
648+
node->ioss_ScanKeys,node->ioss_NumScanKeys,
649+
node->ioss_OrderByKeys,node->ioss_NumOrderByKeys);
650+
}
651+
652+
/* ----------------------------------------------------------------
653+
*ExecIndexOnlyScanInitializeWorker
654+
*
655+
*Copy relevant information from TOC into planstate.
656+
* ----------------------------------------------------------------
657+
*/
658+
void
659+
ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState*node,shm_toc*toc)
660+
{
661+
ParallelIndexScanDescpiscan;
662+
663+
piscan=shm_toc_lookup(toc,node->ss.ps.plan->plan_node_id);
664+
node->ioss_ScanDesc=
665+
index_beginscan_parallel(node->ss.ss_currentRelation,
666+
node->ioss_RelationDesc,
667+
node->ioss_NumScanKeys,
668+
node->ioss_NumOrderByKeys,
669+
piscan);
670+
node->ioss_ScanDesc->xs_want_itup= true;
671+
672+
/*
673+
* If no run-time keys to calculate, go ahead and pass the scankeys to the
674+
* index AM.
675+
*/
676+
if (node->ioss_NumRuntimeKeys==0)
677+
index_rescan(node->ioss_ScanDesc,
678+
node->ioss_ScanKeys,node->ioss_NumScanKeys,
679+
node->ioss_OrderByKeys,node->ioss_NumOrderByKeys);
680+
}

‎src/backend/optimizer/path/indxpath.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1048,9 +1048,9 @@ build_index_paths(PlannerInfo *root, RelOptInfo *rel,
10481048

10491049
/*
10501050
* If appropriate, consider parallel index scan. We don't allow
1051-
* parallel index scan for bitmaporindex only scans.
1051+
* parallel index scan for bitmap index scans.
10521052
*/
1053-
if (index->amcanparallel&& !index_only_scan&&
1053+
if (index->amcanparallel&&
10541054
rel->consider_parallel&&outer_relids==NULL&&
10551055
scantype!=ST_BITMAPSCAN)
10561056
{
@@ -1104,7 +1104,7 @@ build_index_paths(PlannerInfo *root, RelOptInfo *rel,
11041104
result=lappend(result,ipath);
11051105

11061106
/* If appropriate, consider parallel index scan */
1107-
if (index->amcanparallel&& !index_only_scan&&
1107+
if (index->amcanparallel&&
11081108
rel->consider_parallel&&outer_relids==NULL&&
11091109
scantype!=ST_BITMAPSCAN)
11101110
{

‎src/include/executor/nodeIndexonlyscan.h‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@
1515
#defineNODEINDEXONLYSCAN_H
1616

1717
#include"nodes/execnodes.h"
18+
#include"access/parallel.h"
1819

1920
externIndexOnlyScanState*ExecInitIndexOnlyScan(IndexOnlyScan*node,EState*estate,inteflags);
2021
externTupleTableSlot*ExecIndexOnlyScan(IndexOnlyScanState*node);
@@ -23,4 +24,12 @@ extern void ExecIndexOnlyMarkPos(IndexOnlyScanState *node);
2324
externvoidExecIndexOnlyRestrPos(IndexOnlyScanState*node);
2425
externvoidExecReScanIndexOnlyScan(IndexOnlyScanState*node);
2526

27+
/* Support functions for parallel index-only scans */
28+
externvoidExecIndexOnlyScanEstimate(IndexOnlyScanState*node,
29+
ParallelContext*pcxt);
30+
externvoidExecIndexOnlyScanInitializeDSM(IndexOnlyScanState*node,
31+
ParallelContext*pcxt);
32+
externvoidExecIndexOnlyScanInitializeWorker(IndexOnlyScanState*node,
33+
shm_toc*toc);
34+
2635
#endif/* NODEINDEXONLYSCAN_H */

‎src/include/nodes/execnodes.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1409,6 +1409,7 @@ typedef struct IndexScanState
14091409
*ScanDesc index scan descriptor
14101410
*VMBuffer buffer in use for visibility map testing, if any
14111411
*HeapFetches number of tuples we were forced to fetch from heap
1412+
*ioss_PscanLen Size of parallel index-only scan descriptor
14121413
* ----------------
14131414
*/
14141415
typedefstructIndexOnlyScanState
@@ -1427,6 +1428,7 @@ typedef struct IndexOnlyScanState
14271428
IndexScanDescioss_ScanDesc;
14281429
Bufferioss_VMBuffer;
14291430
longioss_HeapFetches;
1431+
Sizeioss_PscanLen;
14301432
}IndexOnlyScanState;
14311433

14321434
/* ----------------

‎src/test/regress/expected/select_parallel.out‎

Lines changed: 25 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -92,12 +92,14 @@ explain (costs off)
9292
explain (costs off)
9393
select sum(parallel_restricted(unique1)) from tenk1
9494
group by(parallel_restricted(unique1));
95-
QUERY PLAN
96-
----------------------------------------------------
95+
QUERY PLAN
96+
-------------------------------------------------------------------
9797
HashAggregate
9898
Group Key: parallel_restricted(unique1)
99-
-> Index Only Scan using tenk1_unique1 on tenk1
100-
(3 rows)
99+
-> Gather
100+
Workers Planned: 4
101+
-> Parallel Index Only Scan using tenk1_unique1 on tenk1
102+
(5 rows)
101103

102104
-- test parallel plans for queries containing un-correlated subplans.
103105
alter table tenk2 set (parallel_workers = 0);
@@ -146,6 +148,25 @@ select count((unique1)) from tenk1 where hundred > 1;
146148
9800
147149
(1 row)
148150

151+
-- test parallel index-only scans.
152+
explain (costs off)
153+
select count(*) from tenk1 where thousand > 95;
154+
QUERY PLAN
155+
--------------------------------------------------------------------------------
156+
Finalize Aggregate
157+
-> Gather
158+
Workers Planned: 4
159+
-> Partial Aggregate
160+
-> Parallel Index Only Scan using tenk1_thous_tenthous on tenk1
161+
Index Cond: (thousand > 95)
162+
(6 rows)
163+
164+
select count(*) from tenk1 where thousand > 95;
165+
count
166+
-------
167+
9040
168+
(1 row)
169+
149170
reset enable_seqscan;
150171
reset enable_bitmapscan;
151172
set force_parallel_mode=1;

‎src/test/regress/sql/select_parallel.sql‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -56,6 +56,11 @@ explain (costs off)
5656
selectcount((unique1))from tenk1where hundred>1;
5757
selectcount((unique1))from tenk1where hundred>1;
5858

59+
-- test parallel index-only scans.
60+
explain (costs off)
61+
selectcount(*)from tenk1where thousand>95;
62+
selectcount(*)from tenk1where thousand>95;
63+
5964
reset enable_seqscan;
6065
reset enable_bitmapscan;
6166

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