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Support CREATE ACCESS METHOD

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This enables external code to create access methods.  This is useful so
that extensions can add their own access methods which can be formally
tracked for dependencies, so that DROP operates correctly.  Also, having
explicit support makes pg_dump work correctly.

Currently only index AMs are supported, but we expect different types to
be added in the future.

Authors: Alexander Korotkov, Petr Jelínek
Reviewed-By: Teodor Sigaev, Petr Jelínek, Jim Nasby
Commitfest-URL: https://commitfest.postgresql.org/9/353/
Discussion: https://www.postgresql.org/message-id/CAPpHfdsXwZmojm6Dx+TJnpYk27kT4o7Ri6X_4OSWcByu1Rm+VA@mail.gmail.com
This commit is contained in:
Alvaro Herrera
2016-03-23 23:01:35 -03:00
parent 2c6af4f442
commit 473b932870
37 changed files with 1150 additions and 101 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
doc/src/sgml/indexam.sgml
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@ -57,6 +57,12 @@
to insert an appropriate row for themselves.
</para>
<para>
Index access access methods can be defined and dropped using
<xref linkend="sql-create-access-method"> and
<xref linkend="sql-drop-access-method"> SQL commands respectively.
</para>
<para>
An index access method handler function must be declared to accept a
single argument of type <type>internal</> and to return the

2
doc/src/sgml/ref/allfiles.sgml
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@ -52,6 +52,7 @@ Complete list of usable sgml source files in this directory.
<!ENTITY commit SYSTEM "commit.sgml">
<!ENTITY commitPrepared SYSTEM "commit_prepared.sgml">
<!ENTITY copyTable SYSTEM "copy.sgml">
<!ENTITY createAccessMethod SYSTEM "create_access_method.sgml">
<!ENTITY createAggregate SYSTEM "create_aggregate.sgml">
<!ENTITY createCast SYSTEM "create_cast.sgml">
<!ENTITY createCollation SYSTEM "create_collation.sgml">
@ -94,6 +95,7 @@ Complete list of usable sgml source files in this directory.
<!ENTITY delete SYSTEM "delete.sgml">
<!ENTITY discard SYSTEM "discard.sgml">
<!ENTITY do SYSTEM "do.sgml">
<!ENTITY dropAccessMethod SYSTEM "drop_access_method.sgml">
<!ENTITY dropAggregate SYSTEM "drop_aggregate.sgml">
<!ENTITY dropCast SYSTEM "drop_cast.sgml">
<!ENTITY dropCollation SYSTEM "drop_collation.sgml">

120
doc/src/sgml/ref/create_access_method.sgml Normal file
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@ -0,0 +1,120 @@
<!--
doc/src/sgml/ref/create_access_method.sgml
PostgreSQL documentation
-->
<refentry id="sql-create-access-method">
<indexterm zone="sql-create-access-method">
<primary>CREATE ACCESS METHOD</primary>
</indexterm>
<refmeta>
<refentrytitle>CREATE ACCESS METHOD</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>CREATE ACCESS METHOD</refname>
<refpurpose>define a new access method</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
CREATE ACCESS METHOD <replaceable class="parameter">name</replaceable>
TYPE <replaceable class="parameter">access_method_type</replaceable>
HANDLER <replaceable class="parameter">handler_function</replaceable>
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>CREATE ACCESS METHOD</command> creates a new access method.
</para>
<para>
The access method name must be unique within the database.
</para>
<para>
Only superusers can define new access methods.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name of the access method to be created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>access_method_type</literal></term>
<listitem>
<para>
This clause specifies type of access method to define.
Only <literal>INDEX</literal> is supported at present.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>HANDLER <replaceable class="parameter">handler_function</replaceable></literal></term>
<listitem>
<para><replaceable class="parameter">handler_function</replaceable> is the
name of a previously registered function that will be called to
retrieve the struct which contains required parameters and functions
of access method to the core. The handler function must take single
argument of type <type>internal</>, and its return type depends on the
type of access method; for <literal>INDEX</literal> access methods, it
must be <type>index_am_handler</type>.
</para>
<para>
See <xref linkend="index-api"> for index access methods API.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Create an access method <literal>heptree</> with
handler function <literal>heptree_handler</>:
<programlisting>
CREATE ACCESS METHOD heptree TYPE INDEX HANDLER heptree_handler;
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>CREATE ACCESS METHOD</command> is a
<productname>PostgreSQL</> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-drop-access-method"></member>
<member><xref linkend="sql-createopclass"></member>
<member><xref linkend="sql-createopfamily"></member>
</simplelist>
</refsect1>
</refentry>

112
doc/src/sgml/ref/drop_access_method.sgml Normal file
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@ -0,0 +1,112 @@
<!--
doc/src/sgml/ref/drop_access_method.sgml
PostgreSQL documentation
-->
<refentry id="sql-drop-access-method">
<indexterm zone="sql-drop-access-method">
<primary>DROP ACCESS METHOD</primary>
</indexterm>
<refmeta>
<refentrytitle>DROP ACCESS METHOD</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>DROP ACCESS METHOD</refname>
<refpurpose>remove an access method</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
DROP ACCESS METHOD [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>DROP ACCESS METHOD</command> removes an existing access method.
Only superusers can drop access methods.
</para>
<para>
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF EXISTS</literal></term>
<listitem>
<para>
Do not throw an error if the access method does not exist.
A notice is issued in this case.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name of an existing access method.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the access method
(such as operator classes, operator families, indexes).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Refuse to drop the access method if any objects depend on it.
This is the default.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Drop the access method <literal>heptree</>:
<programlisting>
DROP ACCESS METHOD heptree;
</programlisting></para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>DROP ACCESS METHOD</command> is a
<productname>PostgreSQL</> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-create-access-method"></member>
</simplelist>
</refsect1>
</refentry>

2
doc/src/sgml/reference.sgml
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@ -80,6 +80,7 @@
&commit;
&commitPrepared;
&copyTable;
&createAccessMethod;
&createAggregate;
&createCast;
&createCollation;
@ -122,6 +123,7 @@
&delete;
&discard;
&do;
&dropAccessMethod;
&dropAggregate;
&dropCast;
&dropCollation;