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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2024-03-27 13:39:03 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2024-03-27 13:39:03 -0400 |
| commit | 25675c474292dca71470ef17ea8a53c150eb0e0a (patch) | |
| tree | 8c224acedb1bc2065ca373ab20bbfb0bd5a88639 | |
| parent | a8b7408686a5576cf3b102dcbec61d37dde04b02 (diff) | |
| download | postgresql-25675c474292dca71470ef17ea8a53c150eb0e0a.tar.gz postgresql-25675c474292dca71470ef17ea8a53c150eb0e0a.zip | |
Fix unnecessary use of moving-aggregate mode with non-moving frame.
When a plain aggregate is used as a window function, and the window
frame start is specified as UNBOUNDED PRECEDING, the frame's head
cannot move so we do not need to use moving-aggregate mode. The check
for that was put into initialize_peragg(), failing to notice that
ExecInitWindowAgg() calls that function before it's filled in
winstate->frameOptions. Since makeNode() would have zeroed the field,
this didn't provoke uninitialized-value complaints, nor would the
erroneous decision have resulted in more than a little inefficiency.
Still, it's wrong, so move the initialization of
winstate->frameOptions earlier to make it work properly.
While here, also fix a thinko in a comment. Both errors crept in in
commit a9d9acbf2 which introduced the moving-aggregate mode.
Spotted by Vallimaharajan G. Back-patch to all supported branches.
Discussion: https://postgr.es/m/18e7f2a5167.fe36253866818.977923893562469143@zohocorp.com
| -rw-r--r-- | src/backend/executor/nodeWindowAgg.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c index bf4841654f6..111293f128c 100644 --- a/src/backend/executor/nodeWindowAgg.c +++ b/src/backend/executor/nodeWindowAgg.c @@ -2273,6 +2273,9 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags) winstate->ss.ps.state = estate; winstate->ss.ps.ExecProcNode = ExecWindowAgg; + /* copy frame options to state node for easy access */ + winstate->frameOptions = frameOptions; + /* * Create expression contexts. We need two, one for per-input-tuple * processing and one for per-output-tuple processing. We cheat a little @@ -2500,9 +2503,6 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags) winstate->agg_winobj = agg_winobj; } - /* copy frame options to state node for easy access */ - winstate->frameOptions = frameOptions; - /* initialize frame bound offset expressions */ winstate->startOffset = ExecInitExpr((Expr *) node->startOffset, (PlanState *) winstate); @@ -2653,7 +2653,7 @@ initialize_peragg(WindowAggState *winstate, WindowFunc *wfunc, /* * Figure out whether we want to use the moving-aggregate implementation, - * and collect the right set of fields from the pg_attribute entry. + * and collect the right set of fields from the pg_aggregate entry. * * It's possible that an aggregate would supply a safe moving-aggregate * implementation and an unsafe normal one, in which case our hand is |