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Cherry-pick preparational patches for stat transfer #55

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74849e7
pg_dump: Add dumpSchema and dumpData derivative flags.
nathan-bossart Nov 25, 2024
cad405c
Add --no-sync to pg_upgrade's uses of pg_dump and pg_dumpall.
nathan-bossart Jul 1, 2024
ffbc5c9
Create functions pg_set_relation_stats, pg_clear_relation_stats.
jeff-davis Oct 11, 2024
0d55f8c
Create functions pg_set_relation_stats, pg_clear_relation_stats.
jeff-davis Oct 11, 2024
676fdc0
Allow pg_set_relation_stats() to set relpages to -1.
jeff-davis Oct 18, 2024
f85dd46
Disable autovacuum for tables in stats import tests.
jeff-davis Oct 18, 2024
0e39dc6
Change pg_*_relation_stats() functions to return type to void.
jeff-davis Oct 22, 2024
df14860
Add functions pg_set_attribute_stats() and pg_clear_attribute_stats().
jeff-davis Oct 22, 2024
9e5bf6e
Improve pg_set_attribute_stats() error message.
jeff-davis Oct 23, 2024
21d4d23
Add functions pg_restore_relation_stats(), pg_restore_attribute_stats().
jeff-davis Oct 24, 2024
9f7ece7
Disallow modifying statistics on system columns.
jeff-davis Nov 22, 2024
e496467
Use in-place updates for pg_restore_relation_stats().
jeff-davis Dec 11, 2024
032d2dc
Compat fix
reshke Nov 19, 2025
ff41cac
Fix pgproc
reshke Nov 19, 2025
cf021fd
fix pg_set_relation_stats
reshke Nov 19, 2025
8ae03cf
fix include
reshke Nov 19, 2025
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271 changes: 271 additions & 0 deletions doc/src/sgml/func.sgml
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Expand Up @@ -28025,6 +28025,277 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
</tgroup>
</table>

<para>
<xref linkend="functions-admin-statsmod"/> lists functions used to
manipulate statistics.
<warning>
<para>
Changes made by these statistics manipulation functions are likely to be
overwritten by <link linkend="autovacuum">autovacuum</link> (or manual
<command>VACUUM</command> or <command>ANALYZE</command>) and should be
considered temporary.
</para>
</warning>
</para>

<table id="functions-admin-statsmod">
<title>Database Object Statistics Manipulation Functions</title>
<tgroup cols="1">
<thead>
<row>
<entry role="func_table_entry"><para role="func_signature">
Function
</para>
<para>
Description
</para></entry>
</row>
</thead>

<tbody>
<row>
<entry role="func_table_entry">
<para role="func_signature">
<indexterm>
<primary>pg_set_relation_stats</primary>
</indexterm>
<function>pg_set_relation_stats</function> (
<parameter>relation</parameter> <type>regclass</type>
<optional>, <parameter>relpages</parameter> <type>integer</type></optional>
<optional>, <parameter>reltuples</parameter> <type>real</type></optional>
<optional>, <parameter>relallvisible</parameter> <type>integer</type></optional> )
<returnvalue>void</returnvalue>
</para>
<para>
Updates relation-level statistics for the given relation to the
specified values. The parameters correspond to columns in <link
linkend="catalog-pg-class"><structname>pg_class</structname></link>. Unspecified
or <literal>NULL</literal> values leave the setting unchanged.
</para>
<para>
Ordinarily, these statistics are collected automatically or updated
as a part of <xref linkend="sql-vacuum"/> or <xref
linkend="sql-analyze"/>, so it's not necessary to call this
function. However, it may be useful when testing the effects of
statistics on the planner to understand or anticipate plan changes.
</para>
<para>
The caller must have the <literal>MAINTAIN</literal> privilege on
the table or be the owner of the database.
</para>
<para>
The value of <structfield>relpages</structfield> must be greater than
or equal to <literal>-1</literal>,
<structfield>reltuples</structfield> must be greater than or equal to
<literal>-1.0</literal>, and <structfield>relallvisible</structfield>
must be greater than or equal to <literal>0</literal>.
</para>
</entry>
</row>

<row>
<entry role="func_table_entry">
<para role="func_signature">
<indexterm>
<primary>pg_clear_relation_stats</primary>
</indexterm>
<function>pg_clear_relation_stats</function> ( <parameter>relation</parameter> <type>regclass</type> )
<returnvalue>void</returnvalue>
</para>
<para>
Clears table-level statistics for the given relation, as though the
table was newly created.
</para>
<para>
The caller must have the <literal>MAINTAIN</literal> privilege on
the table or be the owner of the database.
</para>
</entry>
</row>

<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_restore_relation_stats</primary>
</indexterm>
<function>pg_restore_relation_stats</function> (
<literal>VARIADIC</literal> <parameter>kwargs</parameter> <type>"any"</type> )
<returnvalue>boolean</returnvalue>
</para>
<para>
Similar to <function>pg_set_relation_stats()</function>, but intended
for bulk restore of relation statistics. The tracked statistics may
change from version to version, so the primary purpose of this
function is to maintain a consistent function signature to avoid
errors when restoring statistics from previous versions.
</para>
<para>
To match the behavior of <xref linkend="sql-vacuum"/> and <xref
linkend="sql-analyze"/> when updating relation statistics,
<function>pg_restore_relation_stats()</function> does not follow MVCC
transactional semantics (see <xref linkend="mvcc"/>). New relation
statistics may be durable even if the transaction aborts, and the
changes are not isolated from other transactions.
</para>
<para>
Arguments are passed as pairs of <replaceable>argname</replaceable>
and <replaceable>argvalue</replaceable>, where
<replaceable>argname</replaceable> corresponds to a named argument in
<function>pg_set_relation_stats()</function> and
<replaceable>argvalue</replaceable> is of the corresponding type.
</para>
<para>
Additionally, this function supports argument name
<literal>version</literal> of type <type>integer</type>, which
specifies the version from which the statistics originated, improving
intepretation of older statistics.
</para>
<para>
For example, to set the <structname>relpages</structname> and
<structname>reltuples</structname> of the table
<structname>mytable</structname>:
<programlisting>
SELECT pg_restore_relation_stats(
'relation', 'mytable'::regclass,
'relpages', 173::integer,
'reltuples', 10000::float4);
</programlisting>
</para>
<para>
Minor errors are reported as a <literal>WARNING</literal> and
ignored, and remaining statistics will still be restored. If all
specified statistics are successfully restored, return
<literal>true</literal>, otherwise <literal>false</literal>.
</para>
</entry>
</row>

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

<row>
<entry role="func_table_entry">
<para role="func_signature">
<indexterm>
<primary>pg_clear_attribute_stats</primary>
</indexterm>
<function>pg_clear_attribute_stats</function> (
<parameter>relation</parameter> <type>regclass</type>,
<parameter>attname</parameter> <type>name</type>,
<parameter>inherited</parameter> <type>boolean</type> )
<returnvalue>boolean</returnvalue>
</para>
<para>
Clears table-level statistics for the given relation attribute, as
though the table was newly created.
</para>
<para>
The caller must have the <literal>MAINTAIN</literal> privilege on
the table or be the owner of the database.
</para>
</entry>
</row>

<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_restore_attribute_stats</primary>
</indexterm>
<function>pg_restore_attribute_stats</function> (
<literal>VARIADIC</literal> <parameter>kwargs</parameter> <type>"any"</type> )
<returnvalue>boolean</returnvalue>
</para>
<para>
Similar to <function>pg_set_attribute_stats()</function>, but
intended for bulk restore of attribute statistics. The tracked
statistics may change from version to version, so the primary purpose
of this function is to maintain a consistent function signature to
avoid errors when restoring statistics from previous versions.
</para>
<para>
Arguments are passed as pairs of <replaceable>argname</replaceable>
and <replaceable>argvalue</replaceable>, where
<replaceable>argname</replaceable> corresponds to a named argument in
<function>pg_set_attribute_stats()</function> and
<replaceable>argvalue</replaceable> is of the corresponding type.
</para>
<para>
Additionally, this function supports argument name
<literal>version</literal> of type <type>integer</type>, which
specifies the version from which the statistics originated, improving
intepretation of older statistics.
</para>
<para>
For example, to set the <structname>avg_width</structname> and
<structname>null_frac</structname> for the attribute
<structname>col1</structname> of the table
<structname>mytable</structname>:
<programlisting>
SELECT pg_restore_attribute_stats(
'relation', 'mytable'::regclass,
'attname', 'col1'::name,
'inherited', false,
'avg_width', 125::integer,
'null_frac', 0.5::real);
</programlisting>
</para>
<para>
Minor errors are reported as a <literal>WARNING</literal> and
ignored, and remaining statistics will still be restored. If all
specified statistics are successfully restored, return
<literal>true</literal>, otherwise <literal>false</literal>.
</para>
</entry>
</row>
</tbody>
</tgroup>
</table>

<para>
<xref linkend="functions-info-partition"/> lists functions that provide
information about the structure of partitioned tables.
Expand Down
32 changes: 32 additions & 0 deletions src/backend/catalog/system_functions.sql
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Expand Up @@ -601,6 +601,38 @@ LANGUAGE internal
STRICT IMMUTABLE PARALLEL SAFE
AS 'unicode_is_normalized';

CREATE OR REPLACE FUNCTION
pg_set_relation_stats(relation regclass,
relpages integer DEFAULT NULL,
reltuples real DEFAULT NULL,
relallvisible integer DEFAULT NULL)
RETURNS void
LANGUAGE INTERNAL
CALLED ON NULL INPUT VOLATILE
AS 'pg_set_relation_stats';

CREATE OR REPLACE FUNCTION
pg_set_attribute_stats(relation regclass,
attname name,
inherited bool,
null_frac real DEFAULT NULL,
avg_width integer DEFAULT NULL,
n_distinct real DEFAULT NULL,
most_common_vals text DEFAULT NULL,
most_common_freqs real[] DEFAULT NULL,
histogram_bounds text DEFAULT NULL,
correlation real DEFAULT NULL,
most_common_elems text DEFAULT NULL,
most_common_elem_freqs real[] DEFAULT NULL,
elem_count_histogram real[] DEFAULT NULL,
range_length_histogram text DEFAULT NULL,
range_empty_frac real DEFAULT NULL,
range_bounds_histogram text DEFAULT NULL)
RETURNS void
LANGUAGE INTERNAL
CALLED ON NULL INPUT VOLATILE
AS 'pg_set_attribute_stats';

--
-- The default permissions for functions mean that anyone can execute them.
-- A number of functions shouldn't be executable by just anyone, but rather
Expand Down
5 changes: 4 additions & 1 deletion src/backend/statistics/Makefile
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Expand Up @@ -13,9 +13,12 @@ top_builddir = ../../..
include $(top_builddir)/src/Makefile.global

OBJS = \
attribute_stats.o \
dependencies.o \
extended_stats.o \
mcv.o \
mvdistinct.o
mvdistinct.o \
relation_stats.o \
stat_utils.o

include $(top_srcdir)/src/backend/common.mk
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