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

Commitc442722

Browse files
committed
Fix handling of REWIND/MARK/BACKWARD in incremental sort
The executor flags were not handled entirely correctly, although thebugs were mostly harmless and it was mostly comment inaccuracy. We don'tneed to strip any of the flags for child nodes.Incremental sort does not support backward scans of mark/restore, soMARK/BACKWARDS flags should not be possible. So we simply ensure thisusing an assert, and we don't bother removing them when initializingthe child node.With REWIND it's a bit less clear - incremental sort does not supportREWIND, but there is no way to signal this - it's legal to just ignorethe flag. We however continue passing the flag to child nodes, becausethey might be useful to leverage that.Reported-by: Michael PaquierAuthor: James ColemanReviewed-by: Tomas VondraDiscussion:https://postgr.es/m/20200414065336.GI1492@paquier.xyz
1 parent6c29888 commitc442722

File tree

1 file changed

+10
-10
lines changed

1 file changed

+10
-10
lines changed

‎src/backend/executor/nodeIncrementalSort.c

Lines changed: 10 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -986,12 +986,11 @@ ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags)
986986
SO_printf("ExecInitIncrementalSort: initializing sort node\n");
987987

988988
/*
989-
* Incremental sort can't be used witheither EXEC_FLAG_REWIND,
990-
*EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK, because weonly oneof many sort
991-
*batches inthecurrent sort state.
989+
* Incremental sort can't be used withEXEC_FLAG_BACKWARD or EXEC_FLAG_MARK,
990+
*because the current sort state containsonly onesort batch rather than
991+
* thefull result set.
992992
*/
993-
Assert((eflags& (EXEC_FLAG_BACKWARD |
994-
EXEC_FLAG_MARK))==0);
993+
Assert((eflags& (EXEC_FLAG_BACKWARD |EXEC_FLAG_MARK))==0);
995994

996995
/* Initialize state structure. */
997996
incrsortstate=makeNode(IncrementalSortState);
@@ -1041,11 +1040,11 @@ ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags)
10411040
/*
10421041
* Initialize child nodes.
10431042
*
1044-
* We shield the child node from the need to support REWIND, BACKWARD, or
1045-
* MARK/RESTORE.
1043+
* Incremental sort does not support backwards scans and mark/restore, so
1044+
* we don't bother removing the flags from eflags here. We allow passing
1045+
* a REWIND flag, because although incremental sort can't use it, the child
1046+
* nodes may be able to do something more useful.
10461047
*/
1047-
eflags &= ~(EXEC_FLAG_REWIND |EXEC_FLAG_BACKWARD |EXEC_FLAG_MARK);
1048-
10491048
outerPlanState(incrsortstate)=ExecInitNode(outerPlan(node),estate,eflags);
10501049

10511050
/*
@@ -1126,7 +1125,8 @@ ExecReScanIncrementalSort(IncrementalSortState *node)
11261125
* store all tuples at once for the full sort.
11271126
*
11281127
* So even if EXEC_FLAG_REWIND is set we just reset all of our state and
1129-
* reexecute the sort along with the child node below us.
1128+
* re-execute the sort along with the child node. Incremental sort itself
1129+
* can't do anything smarter, but maybe the child nodes can.
11301130
*
11311131
* In theory if we've only filled the full sort with one batch (and haven't
11321132
* reset it for a new batch yet) then we could efficiently rewind, but

0 commit comments

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