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| author | Simon Riggs <simon@2ndQuadrant.com> | 2017-04-05 18:00:42 -0400 |
|---|---|---|
| committer | Simon Riggs <simon@2ndQuadrant.com> | 2017-04-05 18:00:42 -0400 |
| commit | 2686ee1b7ccfb9214064d4d2a98ea77382880306 (patch) | |
| tree | 32095d935e240b93ed30b1e86c2efa161cffa4dd /src/backend/tcop/postgres.c | |
| parent | 00b6b6feb12cef53737287b67ecef6aff1f1d8ab (diff) | |
| download | postgresql-2686ee1b7ccfb9214064d4d2a98ea77382880306.tar.gz postgresql-2686ee1b7ccfb9214064d4d2a98ea77382880306.zip | |
Collect and use multi-column dependency stats
Follow on patch in the multi-variate statistics patch series.
CREATE STATISTICS s1 WITH (dependencies) ON (a, b) FROM t;
ANALYZE;
will collect dependency stats on (a, b) and then use the measured
dependency in subsequent query planning.
Commit 7b504eb282ca2f5104b5c00b4f05a3ef6bb1385b added
CREATE STATISTICS with n-distinct coefficients. These are now
specified using the mutually exclusive option WITH (ndistinct).
Author: Tomas Vondra, David Rowley
Reviewed-by: Kyotaro HORIGUCHI, Álvaro Herrera, Dean Rasheed, Robert Haas
and many other comments and contributions
Discussion: https://postgr.es/m/56f40b20-c464-fad2-ff39-06b668fac47c@2ndquadrant.com
Diffstat (limited to 'src/backend/tcop/postgres.c')
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