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Repair error noticed by Roberto Cornacchia: selectivity code

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was rejecting negative attnums as bogus, which of course they are not.
Add code to get_attdisbursion to produce a useful value for OID attribute,
since VACUUM does not store stats for system attributes.
Also, repair bug that's been in eqjoinsel for a long time: it was taking
the max of the two columns' disbursions, whereas it should use the min.
This commit is contained in:
Tom Lane
1999-09-09 02:36:04 +00:00
parent 45500964f6
commit 51db6455ea
5 changed files with 67 additions and 38 deletions
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10
src/backend/utils/cache/lsyscache.c vendored
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@ -6,7 +6,7 @@
* Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.33 1999/08/16 02:06:25 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.34 1999/09/09 02:36:04 tgl Exp $
*
* NOTES
* Eventually, the index information should go through here, too.
@ -223,6 +223,14 @@ get_attdisbursion(Oid relid, AttrNumber attnum, double min_estimate)
if (disbursion < 0.0) /* VACUUM thinks there are no duplicates */
return 1.0 / (double) ntuples;
/*
* VACUUM ANALYZE does not compute disbursion for system attributes,
* but some of them can reasonably be assumed unique anyway.
*/
if (attnum == ObjectIdAttributeNumber ||
attnum == SelfItemPointerAttributeNumber)
return 1.0 / (double) ntuples;
/*
* VACUUM ANALYZE has not been run for this table.
* Produce an estimate = 1/numtuples. This may produce