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VCI module - documentation
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‎doc/src/sgml/contrib.sgml‎

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@@ -176,6 +176,7 @@ CREATE EXTENSION <replaceable>extension_name</replaceable>;
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&tsm-system-time;
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&unaccent;
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&uuid-ossp;
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&vci;
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&xml2;
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</appendix>

‎doc/src/sgml/filelist.sgml‎

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<!ENTITY unaccent SYSTEM "unaccent.sgml">
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<!ENTITY uuid-ossp SYSTEM "uuid-ossp.sgml">
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<!ENTITY vacuumlo SYSTEM "vacuumlo.sgml">
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<!ENTITY vci SYSTEM "vci.sgml">
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<!ENTITY xml2 SYSTEM "xml2.sgml">
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<!-- appendixes -->

‎doc/src/sgml/vci.sgml‎

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<!-- doc/src/sgml/vci.sgml -->
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<sect1 id="vci" xreflabel="vci">
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<title>vci &mdash; Vertical Clustered Index</title>
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<indexterm zone="vci">
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<primary>vci</primary>
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</indexterm>
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<para>
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<literal>vci</literal> provides a columnar store that is implemented using
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<productname>PostgreSQL</productname> index access methods (see <xref linkend="indexam"/>).
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All data can be stored in memory.
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</para>
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<para>
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This module must be loaded by adding <literal>vci</literal> to both
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<xref linkend="guc-shared-preload-libraries"/> and <xref linkend="guc-session-preload-libraries"/>
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in <filename>postgresql.conf</filename>, as it requires additional shared memory.
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A server restart is required to add or remove the module.
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</para>
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<sect2 id="vci-functions">
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<title>Functions</title>
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<variablelist>
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<varlistentry>
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<term>
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<function>vci_runs_in_query() returns bool</function>
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<indexterm>
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<primary>vci_runs_in_query</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
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Returns <literal>true</literal> if a VCI index and custom scan are used
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in the current query execution. This function is typically used to verify
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whether a query is processed using VCI. For example:
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<programlisting>
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SELECT vci_runs_in_query() AS vci_runs_in_query, key, count(*) FROM test_table;
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</programlisting>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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<sect2 id="vci-parameters">
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<title>Parameters</title>
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<variablelist>
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<varlistentry id="guc-vci-cost-threshold" xreflabel="vci.cost_threshold">
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<term>
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<varname>vci.cost_threshold</varname> (<type>integer</type>)
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<indexterm>
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<primary><varname>vci.cost_threshold</varname> configuration parameter</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
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Specifies the CPU cost threshold beyond which the VCI control worker will
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stop running.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-vci-log-query" xreflabel="vci.log_query">
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<term>
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<varname>vci.log_query</varname> (<type>boolean</type>)
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<indexterm>
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<primary><varname>vci.log_query</varname> configuration parameter</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
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Logs a message when a query cannot be executed using VCI.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-vci-maintenance-work-mem" xreflabel="vci.maintenance_work_mem">
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<term>
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<varname>vci.maintenance_work_mem</varname> (<type>integer</type>)
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<indexterm>
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<primary><varname>vci.maintenance_work_mem</varname> configuration parameter</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
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Specifies the maximum amount of memory that can be used by each VCI control
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worker during maintenance operations.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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TBD. There are many more parameters which are not yet documented.
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</para>
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</sect2>
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<sect2 id="vci-examples">
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<title>Examples</title>
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<para>
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TBD. Add examples here.
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</para>
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</sect2>
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<sect2 id="vci-limitations">
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<title>Limitations</title>
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<para>
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<itemizedlist>
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<listitem>
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<para>
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Currently, only a limited set of data types is supported for indexing with VCI.
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</para>
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</listitem>
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<listitem>
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<para>
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This extension does not support the <command>ALTER EXTENSION UPDATE</command> command.
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</para>
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</listitem>
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<listitem>
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<para>
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The command <command>ALTER INDEX</command> cannot be used for VCI indexes.
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</para>
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</listitem>
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<listitem>
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<para>
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VCI indexes cannot be used with the <command>CLUSTER</command> command.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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</sect2>
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<sect2 id="vci-authors">
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<title>Authors</title>
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<para>
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Aya Iwata <email>[email protected]</email>,
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Fujitsu Limited, Kanagawa, Japan
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</para>
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</sect2>
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</sect1>

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