From: Tom Lane Date: Wed, 27 Mar 2024 17:39:03 +0000 (-0400) Subject: Fix unnecessary use of moving-aggregate mode with non-moving frame. X-Git-Tag: REL_16_3~57 X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=a94f51a7bfc9e65ce3799d8cb12945bd596c5ba8;p=postgresql.git 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 --- diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c index 310ac23e3a1..7b5707996c1 100644 --- a/src/backend/executor/nodeWindowAgg.c +++ b/src/backend/executor/nodeWindowAgg.c @@ -2399,6 +2399,9 @@ 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 @@ -2649,9 +2652,6 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags) /* Set the status to running */ winstate->status = WINDOWAGG_RUN; - /* 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); @@ -2802,7 +2802,7 @@ 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