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Add support for multivariate MCV lists

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Introduce a third extended statistic type, supported by the CREATE
STATISTICS command - MCV lists, a generalization of the statistic
already built and used for individual columns.

Compared to the already supported types (n-distinct coefficients and
functional dependencies), MCV lists are more complex, include column
values and allow estimation of much wider range of common clauses
(equality and inequality conditions, IS NULL, IS NOT NULL etc.).
Similarly to the other types, a new pseudo-type (pg_mcv_list) is used.

Author: Tomas Vondra
Reviewed-by: Dean Rasheed, David Rowley, Mark Dilger, Alvaro Herrera
Discussion: https://postgr.es/m/dfdac334-9cf2-2597-fb27-f0fb3753f435@2ndquadrant.com
This commit is contained in:
Tomas Vondra
2019-03-27 18:32:18 +01:00
parent 333ed246c6
commit 7300a69950
32 changed files with 3597 additions and 134 deletions
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2
src/backend/parser/parse_utilcmd.c
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@ -1652,6 +1652,8 @@ generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
stat_types = lappend(stat_types, makeString("ndistinct"));
else if (enabled[i] == STATS_EXT_DEPENDENCIES)
stat_types = lappend(stat_types, makeString("dependencies"));
else if (enabled[i] == STATS_EXT_MCV)
stat_types = lappend(stat_types, makeString("mcv"));
else
elog(ERROR, "unrecognized statistics kind %c", enabled[i]);
}