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Collect and use multi-column dependency stats

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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 7b504eb282 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
This commit is contained in:
Simon Riggs
2017-04-05 18:00:42 -04:00
parent 00b6b6feb1
commit 2686ee1b7c
31 changed files with 2035 additions and 79 deletions
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42
doc/src/sgml/ref/create_statistics.sgml
View File

@@ -21,8 +21,9 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
CREATE STATISTICS [ IF NOT EXISTS ] <replaceable class="PARAMETER">statistics_name</replaceable> ON (
<replaceable class="PARAMETER">column_name</replaceable>, <replaceable class="PARAMETER">column_name</replaceable> [, ...])
CREATE STATISTICS [ IF NOT EXISTS ] <replaceable class="PARAMETER">statistics_name</replaceable>
WITH ( <replaceable class="PARAMETER">option</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] )
ON ( <replaceable class="PARAMETER">column_name</replaceable>, <replaceable class="PARAMETER">column_name</replaceable> [, ...])
FROM <replaceable class="PARAMETER">table_name</replaceable>
</synopsis>
@@ -94,6 +95,41 @@ CREATE STATISTICS [ IF NOT EXISTS ] <replaceable class="PARAMETER">statistics_na
</variablelist>
<refsect2 id="SQL-CREATESTATISTICS-parameters">
<title id="SQL-CREATESTATISTICS-parameters-title">Parameters</title>
<indexterm zone="sql-createstatistics-parameters">
<primary>statistics parameters</primary>
</indexterm>
<para>
The <literal>WITH</> clause can specify <firstterm>options</>
for the statistics. Available options are listed below.
</para>
<variablelist>
<varlistentry>
<term><literal>dependencies</> (<type>boolean</>)</term>
<listitem>
<para>
Enables functional dependencies for the statistics.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ndistinct</> (<type>boolean</>)</term>
<listitem>
<para>
Enables ndistinct coefficients for the statistics.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<refsect1>
@@ -122,7 +158,7 @@ CREATE TABLE t1 (
INSERT INTO t1 SELECT i/100, i/500
FROM generate_series(1,1000000) s(i);
CREATE STATISTICS s1 ON (a, b) FROM t1;
CREATE STATISTICS s1 WITH (dependencies) ON (a, b) FROM t1;
ANALYZE t1;