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Remove useless entries for aggregate functions from fmgrtab.c.

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Gen_fmgrtab.pl treated aggregate functions the same as other built-in
functions, which is wasteful because there is no real need to have
entries for them in the fmgr_builtins[] table.  Suppressing those
entries saves about 3KB in the compiled table on my machine; which
is not a lot but it's not nothing either, considering that that
table is pretty "hot".  The only outside code change needed is
that ExecInitWindowAgg() can't be allowed to call fmgr_info_cxt()
on a plain aggregate function.  But that saves a few cycles anyway.

Having done that, the aggregate_dummy() function is unreferenced
and might as well be dropped.  Using "aggregate_dummy" as the prosrc
value for an aggregate is now just a documentation convention not
something that matters.  There was some discussion of using NULL
instead to save a few bytes in pg_proc, but we'd have to remove
prosrc's BKI_FORCE_NOT_NULL marking which doesn't seem a great idea.
Anyway, it's possible there's client-side code that expects to
see "aggregate_dummy" there, so I'm loath to change it without a
strong reason.

Discussion: https://postgr.es/m/533989.1604263665@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2020-11-04 11:25:56 -05:00
parent 113d3591b8
commit f21636e5d5
4 changed files with 13 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/backend/catalog/pg_aggregate.c
View File

@ -620,7 +620,7 @@ AggregateCreate(const char *aggName,
GetUserId(), /* proowner */
INTERNALlanguageId, /* languageObjectId */
InvalidOid, /* no validator */
"aggregate_dummy", /* placeholder proc */
"aggregate_dummy", /* placeholder (no such proc) */
NULL, /* probin */
PROKIND_AGGREGATE,
false, /* security invoker (currently not

18
src/backend/executor/nodeAgg.c
View File

@ -4935,24 +4935,6 @@ AggRegisterCallback(FunctionCallInfo fcinfo,
}
/*
* aggregate_dummy - dummy execution routine for aggregate functions
*
* This function is listed as the implementation (prosrc field) of pg_proc
* entries for aggregate functions. Its only purpose is to throw an error
* if someone mistakenly executes such a function in the normal way.
*
* Perhaps someday we could assign real meaning to the prosrc field of
* an aggregate?
*/
Datum
aggregate_dummy(PG_FUNCTION_ARGS)
{
elog(ERROR, "aggregate function %u called as normal function",
fcinfo->flinfo->fn_oid);
return (Datum) 0; /* keep compiler quiet */
}
/* ----------------------------------------------------------------
* Parallel Query Support
* ----------------------------------------------------------------

10
src/backend/executor/nodeWindowAgg.c
View File

@ -2446,11 +2446,6 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
perfuncstate->wfuncstate = wfuncstate;
perfuncstate->wfunc = wfunc;
perfuncstate->numArguments = list_length(wfuncstate->args);
fmgr_info_cxt(wfunc->winfnoid, &perfuncstate->flinfo,
econtext->ecxt_per_query_memory);
fmgr_info_set_expr((Node *) wfunc, &perfuncstate->flinfo);
perfuncstate->winCollation = wfunc->inputcollid;
get_typlenbyval(wfunc->wintype,
@ -2479,6 +2474,11 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
winobj->argstates = wfuncstate->args;
winobj->localmem = NULL;
perfuncstate->winobj = winobj;
/* It's a real window function, so set up to call it. */
fmgr_info_cxt(wfunc->winfnoid, &perfuncstate->flinfo,
econtext->ecxt_per_query_memory);
fmgr_info_set_expr((Node *) wfunc, &perfuncstate->flinfo);
}
}

9
src/backend/utils/Gen_fmgrtab.pl
View File

@ -75,6 +75,7 @@ foreach my $row (@{ $catalog_data{pg_proc} })
oid => $bki_values{oid},
name => $bki_values{proname},
lang => $bki_values{prolang},
kind => $bki_values{prokind},
strict => $bki_values{proisstrict},
retset => $bki_values{proretset},
nargs => $bki_values{pronargs},
@ -195,8 +196,10 @@ foreach my $s (sort { $a->{oid} <=> $b->{oid} } @fmgr)
$sqlname .= "_" . $s->{args} if ($proname_counts{ $s->{name} } > 1);
$sqlname =~ s/\s+/_/g;
print $ofh "#define F_" . uc $sqlname . " $s->{oid}\n";
# We want only one extern per internal-language function
if ($s->{lang} eq 'internal' && !$seenit{ $s->{prosrc} })
# We want only one extern per internal-language, non-aggregate function
if ( $s->{lang} eq 'internal'
&& $s->{kind} ne 'a'
&& !$seenit{ $s->{prosrc} })
{
$seenit{ $s->{prosrc} } = 1;
print $pfh "extern Datum $s->{prosrc}(PG_FUNCTION_ARGS);\n";
@ -214,6 +217,8 @@ my $fmgr_count = 0;
foreach my $s (sort { $a->{oid} <=> $b->{oid} } @fmgr)
{
next if $s->{lang} ne 'internal';
# We do not need entries for aggregate functions
next if $s->{kind} eq 'a';
print $tfh ",\n" if ($fmgr_count > 0);
print $tfh