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Allow specifying an access method for partitioned tables

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It's now possible to specify a table access method via
CREATE TABLE ... USING for a partitioned table, as well change it with
ALTER TABLE ... SET ACCESS METHOD.  Specifying an AM for a partitioned
table lets the value be used for all future partitions created under it,
closely mirroring the behavior of the TABLESPACE option for partitioned
tables.  Existing partitions are not modified.

For a partitioned table with no AM specified, any new partitions are
created with the default_table_access_method.

Also add ALTER TABLE ... SET ACCESS METHOD DEFAULT, which reverts to the
original state of using the default for new partitions.

The relcache of partitioned tables is not changed: rd_tableam is not
set, even if a partitioned table has a relam set.

Author: Justin Pryzby <pryzby@telsasoft.com>
Author: Soumyadeep Chakraborty <soumyadeep2007@gmail.com>
Author: Michaël Paquier <michael@paquier.xyz>
Reviewed-by: The authors themselves
Discussion: https://postgr.es/m/CAE-ML+9zM4wJCGCBGv01k96qQ3gFv4WFcFy=zqPHKeaEFwwv6A@mail.gmail.com
Discussion: https://postgr.es/m/20210308010707.GA29832%40telsasoft.com
This commit is contained in:
Alvaro Herrera
2024-03-25 16:30:36 +01:00
parent b8528fe026
commit 374c7a2290
12 changed files with 469 additions and 49 deletions
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10
doc/src/sgml/catalogs.sgml
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@ -1988,9 +1988,13 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
(references <link linkend="catalog-pg-am"><structname>pg_am</structname></link>.<structfield>oid</structfield>)
</para>
<para>
If this is a table or an index, the access method used (heap,
B-tree, hash, etc.); otherwise zero (zero occurs for sequences,
as well as relations without storage, such as views)
The access method used to access this table or index.
Not meaningful if the relation is a sequence or
has no on-disk file,
except for partitioned tables, where, if set, it takes
precedence over <varname>default_table_access_method</varname>
when determining the access method to use for partitions created
when one is not specified in the creation command.
</para></entry>
</row>

18
doc/src/sgml/ref/alter_table.sgml
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@ -732,10 +732,20 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
<term><literal>SET ACCESS METHOD</literal></term>
<listitem>
<para>
This form changes the access method of the table by rewriting it. See
<xref linkend="tableam"/> for more information. Writing
<literal>DEFAULT</literal> changes the access method of the table
to <xref linkend="guc-default-table-access-method"/>.
This form changes the access method of the table by rewriting it
using the indicated access method; specifying
<literal>DEFAULT</literal> selects the access method set as the
<xref linkend="guc-default-table-access-method"/> configuration
parameter.
See <xref linkend="tableam"/> for more information.
</para>
<para>
When applied to a partitioned table, there is no data to rewrite,
but partitions created afterwards will default to the given access
method unless overridden by a <literal>USING</literal> clause.
Specifying <varname>DEFAULT</varname> removes a previous value,
causing future partitions to default to
<varname>default_table_access_method</varname>.
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/create_table.sgml
View File

@ -1365,6 +1365,10 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
method is chosen for the new table. See <xref
linkend="guc-default-table-access-method"/> for more information.
</para>
<para>
When creating a partition, the table access method is the access method
of its partitioned table, if set.
</para>
</listitem>
</varlistentry>