Tom Lane 0e5e167aae Collect and use element-frequency statistics for arrays. ... This patch improves selectivity estimation for the array <@, &&, and @> (containment and overlaps) operators. It enables collection of statistics about individual array element values by ANALYZE, and introduces operator-specific estimators that use these stats. In addition, ScalarArrayOpExpr constructs of the forms "const = ANY/ALL (array_column)" and "const <> ANY/ALL (array_column)" are estimated by treating them as variants of the containment operators. Since we still collect scalar-style stats about the array values as a whole, the pg_stats view is expanded to show both these stats and the array-style stats in separate columns. This creates an incompatible change in how stats for tsvector columns are displayed in pg_stats: the stats about lexemes are now displayed in the array-related columns instead of the original scalar-related columns. There are a few loose ends here, notably that it'd be nice to be able to suppress either the scalar-style stats or the array-element stats for columns for which they're not useful. But the patch is in good enough shape to commit for wider testing. Alexander Korotkov, reviewed by Noah Misch and Nathan Boley		2012-03-03 20:20:57 -05:00
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src	Collect and use element-frequency statistics for arrays.	2012-03-03 20:20:57 -05:00
bug.template	Stamp HEAD as 9.2devel.	2011-06-11 17:46:49 -04:00
KNOWN_BUGS	Remove extra newlines at end and beginning of files, add missing newlines	2010-08-19 05:57:36 +00:00
Makefile	Add maintainer-check target	2011-03-28 22:56:52 +03:00
MISSING_FEATURES	Remove extra newlines at end and beginning of files, add missing newlines	2010-08-19 05:57:36 +00:00
TODO