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Further work on making use of new statistics in planner. Adjust APIs

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of costsize.c routines to pass Query root, so that costsize can figure
more things out by itself and not be so dependent on its callers to tell
it everything it needs to know.  Use selectivity of hash or merge clause
to estimate number of tuples processed internally in these joins
(this is more useful than it would've been before, since eqjoinsel is
somewhat more accurate than before).
This commit is contained in:
Tom Lane
2001-06-05 05:26:05 +00:00
parent 28d2420eef
commit 7c579fa12d
20 changed files with 337 additions and 195 deletions
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10
src/backend/utils/adt/selfuncs.c
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@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.91 2001/05/27 17:37:48 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.92 2001/06/05 05:26:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1132,10 +1132,12 @@ eqjoinsel(PG_FUNCTION_ARGS)
totalsel2 += otherfreq2 * (otherfreq1 + unmatchfreq1) /
(nd1 - nmatches);
/*
* For robustness, we average the two estimates. (Can a case
* be made for taking the min or max instead?)
* Use the smaller of the two estimates. This can be justified
* in essentially the same terms as given below for the no-stats
* case: to a first approximation, we are estimating from the
* point of view of the relation with smaller nd.
*/
selec = (totalsel1 + totalsel2) * 0.5;
selec = (totalsel1 < totalsel2) ? totalsel1 : totalsel2;
}
else
{