Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit355d399

Browse files
committed
Add a Gather Merge executor node.
Like Gather, we spawn multiple workers and run the same plan in eachone; however, Gather Merge is used when each worker produces the sameoutput ordering and we want to preserve that output ordering whilemerging together the streams of tuples from various workers. (In away, Gather Merge is like a hybrid of Gather and MergeAppend.)This works out to a win if it saves us from having to perform anexpensive Sort. In cases where only a small amount of data would needto be sorted, it may actually be faster to use a regular Gather nodeand then sort the results afterward, because Gather Merge sometimesneeds to wait synchronously for tuples whereas a pure Gather generallydoesn't. But if this avoids an expensive sort then it's a win.Rushabh Lathia, reviewed and tested by Amit Kapila, Thomas Munro,and Neha Sharma, and reviewed and revised by me.Discussion:http://postgr.es/m/CAGPqQf09oPX-cQRpBKS0Gq49Z+m6KBxgxd_p9gX8CKk_d75HoQ@mail.gmail.com
1 parenta72f036 commit355d399

File tree

27 files changed

+1355
-16
lines changed

27 files changed

+1355
-16
lines changed

‎doc/src/sgml/config.sgml

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3497,6 +3497,20 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
34973497
</listitem>
34983498
</varlistentry>
34993499

3500+
<varlistentry id="guc-enable-gathermerge" xreflabel="enable_gathermerge">
3501+
<term><varname>enable_gathermerge</varname> (<type>boolean</type>)
3502+
<indexterm>
3503+
<primary><varname>enable_gathermerge</> configuration parameter</primary>
3504+
</indexterm>
3505+
</term>
3506+
<listitem>
3507+
<para>
3508+
Enables or disables the query planner's use of gather
3509+
merge plan types. The default is <literal>on</>.
3510+
</para>
3511+
</listitem>
3512+
</varlistentry>
3513+
35003514
<varlistentry id="guc-enable-hashagg" xreflabel="enable_hashagg">
35013515
<term><varname>enable_hashagg</varname> (<type>boolean</type>)
35023516
<indexterm>

‎src/backend/commands/explain.c

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -918,6 +918,9 @@ ExplainNode(PlanState *planstate, List *ancestors,
918918
caseT_Gather:
919919
pname=sname="Gather";
920920
break;
921+
caseT_GatherMerge:
922+
pname=sname="Gather Merge";
923+
break;
921924
caseT_IndexScan:
922925
pname=sname="Index Scan";
923926
break;
@@ -1411,6 +1414,26 @@ ExplainNode(PlanState *planstate, List *ancestors,
14111414
ExplainPropertyBool("Single Copy",gather->single_copy,es);
14121415
}
14131416
break;
1417+
caseT_GatherMerge:
1418+
{
1419+
GatherMerge*gm= (GatherMerge*)plan;
1420+
1421+
show_scan_qual(plan->qual,"Filter",planstate,ancestors,es);
1422+
if (plan->qual)
1423+
show_instrumentation_count("Rows Removed by Filter",1,
1424+
planstate,es);
1425+
ExplainPropertyInteger("Workers Planned",
1426+
gm->num_workers,es);
1427+
if (es->analyze)
1428+
{
1429+
intnworkers;
1430+
1431+
nworkers= ((GatherMergeState*)planstate)->nworkers_launched;
1432+
ExplainPropertyInteger("Workers Launched",
1433+
nworkers,es);
1434+
}
1435+
}
1436+
break;
14141437
caseT_FunctionScan:
14151438
if (es->verbose)
14161439
{

‎src/backend/executor/Makefile

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -20,7 +20,7 @@ OBJS = execAmi.o execCurrent.o execGrouping.o execIndexing.o execJunk.o \
2020
nodeBitmapHeapscan.o nodeBitmapIndexscan.o\
2121
nodeCustom.o nodeFunctionscan.o nodeGather.o\
2222
nodeHash.o nodeHashjoin.o nodeIndexscan.o nodeIndexonlyscan.o\
23-
nodeLimit.o nodeLockRows.o\
23+
nodeLimit.o nodeLockRows.onodeGatherMerge.o\
2424
nodeMaterial.o nodeMergeAppend.o nodeMergejoin.o nodeModifyTable.o\
2525
nodeNestloop.o nodeProjectSet.o nodeRecursiveunion.o nodeResult.o\
2626
nodeSamplescan.o nodeSeqscan.o nodeSetOp.o nodeSort.o nodeUnique.o\

‎src/backend/executor/execProcnode.c

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -89,6 +89,7 @@
8989
#include"executor/nodeForeignscan.h"
9090
#include"executor/nodeFunctionscan.h"
9191
#include"executor/nodeGather.h"
92+
#include"executor/nodeGatherMerge.h"
9293
#include"executor/nodeGroup.h"
9394
#include"executor/nodeHash.h"
9495
#include"executor/nodeHashjoin.h"
@@ -326,6 +327,11 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
326327
estate,eflags);
327328
break;
328329

330+
caseT_GatherMerge:
331+
result= (PlanState*)ExecInitGatherMerge((GatherMerge*)node,
332+
estate,eflags);
333+
break;
334+
329335
caseT_Hash:
330336
result= (PlanState*)ExecInitHash((Hash*)node,
331337
estate,eflags);
@@ -535,6 +541,10 @@ ExecProcNode(PlanState *node)
535541
result=ExecGather((GatherState*)node);
536542
break;
537543

544+
caseT_GatherMergeState:
545+
result=ExecGatherMerge((GatherMergeState*)node);
546+
break;
547+
538548
caseT_HashState:
539549
result=ExecHash((HashState*)node);
540550
break;
@@ -697,6 +707,10 @@ ExecEndNode(PlanState *node)
697707
ExecEndGather((GatherState*)node);
698708
break;
699709

710+
caseT_GatherMergeState:
711+
ExecEndGatherMerge((GatherMergeState*)node);
712+
break;
713+
700714
caseT_IndexScanState:
701715
ExecEndIndexScan((IndexScanState*)node);
702716
break;
@@ -842,6 +856,9 @@ ExecShutdownNode(PlanState *node)
842856
caseT_CustomScanState:
843857
ExecShutdownCustomScan((CustomScanState*)node);
844858
break;
859+
caseT_GatherMergeState:
860+
ExecShutdownGatherMerge((GatherMergeState*)node);
861+
break;
845862
default:
846863
break;
847864
}

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp