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Commitce207d2

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Add functions pg_set_attribute_stats() and pg_clear_attribute_stats().
Enable manipulation of attribute statistics. Only superficialvalidation is performed, so it's possible to add nonsense, and it's upto the planner (or other users of statistics) to behave reasonably inthat case.Bump catalog version.Author: Corey HuinkerDiscussion:https://postgr.es/m/CADkLM=eErgzn7ECDpwFcptJKOk9SxZEk5Pot4d94eVTZsvj3gw@mail.gmail.com
1 parentdbe6bd4 commitce207d2

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‎doc/src/sgml/func.sgml

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@@ -30222,6 +30222,78 @@ DETAIL: Make sure pg_wal_replay_wait() isn't called within a transaction with a
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</para>
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</entry>
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</row>
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<row>
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<entry role="func_table_entry">
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<para role="func_signature">
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<indexterm>
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<primary>pg_set_attribute_stats</primary>
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</indexterm>
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<function>pg_set_attribute_stats</function> (
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<parameter>relation</parameter> <type>regclass</type>,
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<parameter>attname</parameter> <type>name</type>,
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<parameter>inherited</parameter> <type>boolean</type>
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<optional>, <parameter>null_frac</parameter> <type>real</type></optional>
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<optional>, <parameter>avg_width</parameter> <type>integer</type></optional>
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<optional>, <parameter>n_distinct</parameter> <type>real</type></optional>
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<optional>, <parameter>most_common_vals</parameter> <type>text</type>, <parameter>most_common_freqs</parameter> <type>real[]</type> </optional>
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<optional>, <parameter>histogram_bounds</parameter> <type>text</type> </optional>
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<optional>, <parameter>correlation</parameter> <type>real</type> </optional>
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<optional>, <parameter>most_common_elems</parameter> <type>text</type>, <parameter>most_common_elem_freqs</parameter> <type>real[]</type> </optional>
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<optional>, <parameter>elem_count_histogram</parameter> <type>real[]</type> </optional>
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<optional>, <parameter>range_length_histogram</parameter> <type>text</type> </optional>
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<optional>, <parameter>range_empty_frac</parameter> <type>real</type> </optional>
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<optional>, <parameter>range_bounds_histogram</parameter> <type>text</type> </optional> )
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<returnvalue>void</returnvalue>
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</para>
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<para>
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Creates or updates attribute-level statistics for the given relation
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and attribute name to the specified values. The parameters correspond
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to to attributes of the same name found in the <link
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linkend="view-pg-stats"><structname>pg_stats</structname></link>
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view.
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</para>
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<para>
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Optional parameters default to <literal>NULL</literal>, which leave
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the corresponding statistic unchanged.
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</para>
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<para>
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Ordinarily, these statistics are collected automatically or updated
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as a part of <xref linkend="sql-vacuum"/> or <xref
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linkend="sql-analyze"/>, so it's not necessary to call this
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function. However, it may be useful when testing the effects of
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statistics on the planner to understand or anticipate plan changes.
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</para>
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<para>
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The caller must have the <literal>MAINTAIN</literal> privilege on
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the table or be the owner of the database.
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</para>
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</entry>
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</row>
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<row>
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<entry role="func_table_entry">
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<para role="func_signature">
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<indexterm>
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<primary>pg_clear_attribute_stats</primary>
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</indexterm>
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<function>pg_clear_attribute_stats</function> (
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<parameter>relation</parameter> <type>regclass</type>,
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<parameter>attname</parameter> <type>name</type>,
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<parameter>inherited</parameter> <type>boolean</type> )
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<returnvalue>boolean</returnvalue>
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</para>
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<para>
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Clears table-level statistics for the given relation attribute, as
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though the table was newly created.
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</para>
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<para>
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The caller must have the <literal>MAINTAIN</literal> privilege on
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the table or be the owner of the database.
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</para>
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>

‎src/backend/catalog/system_functions.sql

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@@ -649,6 +649,28 @@ LANGUAGE INTERNAL
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CALLEDONNULL INPUT VOLATILE
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AS'pg_set_relation_stats';
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CREATEOR REPLACE FUNCTION
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pg_set_attribute_stats(relation regclass,
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attname name,
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inherited bool,
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null_fracreal DEFAULTNULL,
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avg_widthinteger DEFAULTNULL,
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n_distinctreal DEFAULTNULL,
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most_common_valstext DEFAULTNULL,
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most_common_freqsreal[] DEFAULTNULL,
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histogram_boundstext DEFAULTNULL,
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correlationreal DEFAULTNULL,
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most_common_elemstext DEFAULTNULL,
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most_common_elem_freqsreal[] DEFAULTNULL,
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elem_count_histogramreal[] DEFAULTNULL,
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range_length_histogramtext DEFAULTNULL,
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range_empty_fracreal DEFAULTNULL,
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range_bounds_histogramtext DEFAULTNULL)
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RETURNS void
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LANGUAGE INTERNAL
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CALLEDONNULL INPUT VOLATILE
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AS'pg_set_attribute_stats';
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--
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-- The default permissions for functions mean that anyone can execute them.
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-- A number of functions shouldn't be executable by just anyone, but rather

‎src/backend/statistics/Makefile

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@@ -13,6 +13,7 @@ top_builddir = ../../..
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include$(top_builddir)/src/Makefile.global
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OBJS =\
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attribute_stats.o\
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dependencies.o\
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extended_stats.o\
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mcv.o\

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