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Add COST and ROWS options to CREATE/ALTER FUNCTION, plus underlying pg_proc

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columns procost and prorows, to allow simple user adjustment of the estimated
cost of a function call, as well as control of the estimated number of rows
returned by a set-returning function.  We might eventually wish to extend this
to allow function-specific estimation routines, but there seems to be
consensus that we should try a simple constant estimate first.  In particular
this provides a relatively simple way to control the order in which different
WHERE clauses are applied in a plan node, which is a Good Thing in view of the
fact that the recent EquivalenceClass planner rewrite made that much less
predictable than before.
This commit is contained in:
Tom Lane
2007-01-22 01:35:23 +00:00
parent a85e9c61e5
commit 5a7471c307
27 changed files with 2550 additions and 2090 deletions
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44
src/backend/utils/cache/lsyscache.c vendored
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.145 2007/01/21 00:57:15 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.146 2007/01/22 01:35:21 tgl Exp $
*
* NOTES
* Eventually, the index information should go through here, too.
@ -1295,6 +1295,48 @@ func_volatile(Oid funcid)
return result;
}
/*
* get_func_cost
* Given procedure id, return the function's procost field.
*/
float4
get_func_cost(Oid funcid)
{
HeapTuple tp;
float4 result;
tp = SearchSysCache(PROCOID,
ObjectIdGetDatum(funcid),
0, 0, 0);
if (!HeapTupleIsValid(tp))
elog(ERROR, "cache lookup failed for function %u", funcid);
result = ((Form_pg_proc) GETSTRUCT(tp))->procost;
ReleaseSysCache(tp);
return result;
}
/*
* get_func_rows
* Given procedure id, return the function's prorows field.
*/
float4
get_func_rows(Oid funcid)
{
HeapTuple tp;
float4 result;
tp = SearchSysCache(PROCOID,
ObjectIdGetDatum(funcid),
0, 0, 0);
if (!HeapTupleIsValid(tp))
elog(ERROR, "cache lookup failed for function %u", funcid);
result = ((Form_pg_proc) GETSTRUCT(tp))->prorows;
ReleaseSysCache(tp);
return result;
}
/* ---------- RELATION CACHE ---------- */
/*