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Add a materialized view relations.

Browse Source 
A materialized view has a rule just like a view and a heap and
other physical properties like a table.  The rule is only used to
populate the table, references in queries refer to the
materialized data.

This is a minimal implementation, but should still be useful in
many cases.  Currently data is only populated "on demand" by the
CREATE MATERIALIZED VIEW and REFRESH MATERIALIZED VIEW statements.
It is expected that future releases will add incremental updates
with various timings, and that a more refined concept of defining
what is "fresh" data will be developed.  At some point it may even
be possible to have queries use a materialized in place of
references to underlying tables, but that requires the other
above-mentioned features to be working first.

Much of the documentation work by Robert Haas.
Review by Noah Misch, Thom Brown, Robert Haas, Marko Tiikkaja
Security review by KaiGai Kohei, with a decision on how best to
implement sepgsql still pending.
This commit is contained in:
Kevin Grittner
2013-03-03 18:23:31 -06:00
parent b15a6da292
commit 3bf3ab8c56
103 changed files with 4238 additions and 436 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
doc/src/sgml/catalogs.sgml
View File

@@ -1597,8 +1597,8 @@
The catalog <structname>pg_class</structname> catalogs tables and most
everything else that has columns or is otherwise similar to a
table. This includes indexes (but see also
<structname>pg_index</structname>), sequences, views, composite types,
and TOAST tables; see <structfield>relkind</>.
<structname>pg_index</structname>), sequences, views, materialized
views, composite types, and TOAST tables; see <structfield>relkind</>.
Below, when we mean all of these
kinds of objects we speak of <quote>relations</quote>. Not all
columns are meaningful for all relation types.
@@ -1789,8 +1789,9 @@
<entry></entry>
<entry>
<literal>r</> = ordinary table, <literal>i</> = index,
<literal>S</> = sequence, <literal>v</> = view, <literal>c</> =
composite type, <literal>t</> = TOAST table,
<literal>S</> = sequence, <literal>v</> = view,
<literal>m</> = materialized view,
<literal>c</> = composite type, <literal>t</> = TOAST table,
<literal>f</> = foreign table
</entry>
</row>

23
doc/src/sgml/func.sgml
View File

@@ -13743,6 +13743,10 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<primary>pg_tablespace_location</primary>
</indexterm>
<indexterm>
<primary>pg_relation_is_scannable</primary>
</indexterm>
<indexterm>
<primary>pg_typeof</primary>
</indexterm>
@@ -13867,29 +13871,29 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<row>
<entry><literal><function>pg_get_viewdef(<parameter>view_name</parameter>)</function></literal></entry>
<entry><type>text</type></entry>
<entry>get underlying <command>SELECT</command> command for view (<emphasis>deprecated</emphasis>)</entry>
<entry>get underlying <command>SELECT</command> command for view or materialized view (<emphasis>deprecated</emphasis>)</entry>
</row>
<row>
<entry><literal><function>pg_get_viewdef(<parameter>view_name</parameter>, <parameter>pretty_bool</>)</function></literal></entry>
<entry><type>text</type></entry>
<entry>get underlying <command>SELECT</command> command for view (<emphasis>deprecated</emphasis>)</entry>
<entry>get underlying <command>SELECT</command> command for view or materialized view (<emphasis>deprecated</emphasis>)</entry>
</row>
<row>
<entry><literal><function>pg_get_viewdef(<parameter>view_oid</parameter>)</function></literal></entry>
<entry><type>text</type></entry>
<entry>get underlying <command>SELECT</command> command for view</entry>
<entry>get underlying <command>SELECT</command> command for view or materialized view</entry>
</row>
<row>
<entry><literal><function>pg_get_viewdef(<parameter>view_oid</parameter>, <parameter>pretty_bool</>)</function></literal></entry>
<entry><type>text</type></entry>
<entry>get underlying <command>SELECT</command> command for view</entry>
<entry>get underlying <command>SELECT</command> command for view or materialized view</entry>
</row>
<row>
<entry><literal><function>pg_get_viewdef(<parameter>view_oid</parameter>, <parameter>wrap_column_int</>)</function></literal></entry>
<entry><type>text</type></entry>
<entry>get underlying <command>SELECT</command> command for view;
lines with fields are wrapped to specified number of columns,
pretty-printing is implied</entry>
<entry>get underlying <command>SELECT</command> command for view or
materialized view; lines with fields are wrapped to specified
number of columns, pretty-printing is implied</entry>
</row>
<row>
<entry><literal><function>pg_options_to_table(<parameter>reloptions</parameter>)</function></literal></entry>
@@ -13906,6 +13910,11 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
<entry><type>text</type></entry>
<entry>get the path in the file system that this tablespace is located in</entry>
</row>
<row>
<entry><literal><function>pg_relation_is_scannable(<parameter>relation_oid</parameter>)</function></literal></entry>
<entry><type>boolean</type></entry>
<entry>is the relation scannable; a materialized view which has not been loaded will not be scannable</entry>
</row>
<row>
<entry><literal><function>pg_typeof(<parameter>any</parameter>)</function></literal></entry>
<entry><type>regtype</type></entry>

4
doc/src/sgml/ref/allfiles.sgml
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@@ -21,6 +21,7 @@ Complete list of usable sgml source files in this directory.
<!ENTITY alterIndex SYSTEM "alter_index.sgml">
<!ENTITY alterLanguage SYSTEM "alter_language.sgml">
<!ENTITY alterLargeObject SYSTEM "alter_large_object.sgml">
<!ENTITY alterMaterializedView SYSTEM "alter_materialized_view.sgml">
<!ENTITY alterOperator SYSTEM "alter_operator.sgml">
<!ENTITY alterOperatorClass SYSTEM "alter_opclass.sgml">
<!ENTITY alterOperatorFamily SYSTEM "alter_opfamily.sgml">
@@ -63,6 +64,7 @@ Complete list of usable sgml source files in this directory.
<!ENTITY createGroup SYSTEM "create_group.sgml">
<!ENTITY createIndex SYSTEM "create_index.sgml">
<!ENTITY createLanguage SYSTEM "create_language.sgml">
<!ENTITY createMaterializedView SYSTEM "create_materialized_view.sgml">
<!ENTITY createOperator SYSTEM "create_operator.sgml">
<!ENTITY createOperatorClass SYSTEM "create_opclass.sgml">
<!ENTITY createOperatorFamily SYSTEM "create_opfamily.sgml">
@@ -102,6 +104,7 @@ Complete list of usable sgml source files in this directory.
<!ENTITY dropGroup SYSTEM "drop_group.sgml">
<!ENTITY dropIndex SYSTEM "drop_index.sgml">
<!ENTITY dropLanguage SYSTEM "drop_language.sgml">
<!ENTITY dropMaterializedView SYSTEM "drop_materialized_view.sgml">
<!ENTITY dropOperator SYSTEM "drop_operator.sgml">
<!ENTITY dropOperatorClass SYSTEM "drop_opclass.sgml">
<!ENTITY dropOperatorFamily SYSTEM "drop_opfamily.sgml">
@@ -136,6 +139,7 @@ Complete list of usable sgml source files in this directory.
<!ENTITY prepare SYSTEM "prepare.sgml">
<!ENTITY prepareTransaction SYSTEM "prepare_transaction.sgml">
<!ENTITY reassignOwned SYSTEM "reassign_owned.sgml">
<!ENTITY refreshMaterializedView SYSTEM "refresh_materialized_view.sgml">
<!ENTITY reindex SYSTEM "reindex.sgml">
<!ENTITY releaseSavepoint SYSTEM "release_savepoint.sgml">
<!ENTITY reset SYSTEM "reset.sgml">

1
doc/src/sgml/ref/alter_extension.sgml
View File

@@ -39,6 +39,7 @@ ALTER EXTENSION <replaceable class="PARAMETER">name</replaceable> DROP <replacea
FOREIGN DATA WRAPPER <replaceable class="PARAMETER">object_name</replaceable> |
FOREIGN TABLE <replaceable class="PARAMETER">object_name</replaceable> |
FUNCTION <replaceable class="PARAMETER">function_name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) |
MATERIALIZED VIEW <replaceable class="PARAMETER">object_name</replaceable> |
OPERATOR <replaceable class="PARAMETER">operator_name</replaceable> (<replaceable class="PARAMETER">left_type</replaceable>, <replaceable class="PARAMETER">right_type</replaceable>) |
OPERATOR CLASS <replaceable class="PARAMETER">object_name</replaceable> USING <replaceable class="parameter">index_method</replaceable> |
OPERATOR FAMILY <replaceable class="PARAMETER">object_name</replaceable> USING <replaceable class="parameter">index_method</replaceable> |

167
doc/src/sgml/ref/alter_materialized_view.sgml Normal file
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@@ -0,0 +1,167 @@
<!--
doc/src/sgml/ref/alter_materialized_view.sgml
PostgreSQL documentation
-->
<refentry id="SQL-ALTERMATERIALIZEDVIEW">
<refmeta>
<refentrytitle>ALTER MATERIALIZED VIEW</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>ALTER MATERIALIZED VIEW</refname>
<refpurpose>change the definition of a materialized view</refpurpose>
</refnamediv>
<indexterm zone="sql-alterview">
<primary>ALTER MATERIALIZED VIEW</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
ALTER MATERIALIZED VIEW [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
<replaceable class="PARAMETER">action</replaceable> [, ... ]
ALTER MATERIALIZED VIEW [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
RENAME [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> TO <replaceable class="PARAMETER">new_column_name</replaceable>
ALTER MATERIALIZED VIEW [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
RENAME TO <replaceable class="parameter">new_name</replaceable>
ALTER MATERIALIZED VIEW [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
SET SCHEMA <replaceable class="parameter">new_schema</replaceable>
<phrase>where <replaceable class="PARAMETER">action</replaceable> is one of:</phrase>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
CLUSTER ON <replaceable class="PARAMETER">index_name</replaceable>
SET WITHOUT CLUSTER
SET ( <replaceable class="PARAMETER">storage_parameter</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
RESET ( <replaceable class="PARAMETER">storage_parameter</replaceable> [, ... ] )
OWNER TO <replaceable class="PARAMETER">new_owner</replaceable>
SET TABLESPACE <replaceable class="PARAMETER">new_tablespace</replaceable>
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>ALTER MATERIALIZED VIEW</command> changes various auxiliary
properties of an existing materialized view.
</para>
<para>
You must own the materialized view to use <command>ALTER MATERIALIZED
VIEW</>. To change a materialized view's schema, you must also have
<literal>CREATE</> privilege on the new schema.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <literal>CREATE</literal> privilege on
the materialized view's schema. (These restrictions enforce that altering
the owner doesn't do anything you couldn't do by dropping and recreating the
materialized view. However, a superuser can alter ownership of any view
anyway.)
</para>
<para>
The statement subforms and actions available for
<command>ALTER MATERIALIZED VIEW</command> are a subset of those available
for <command>ALTER TABLE</command>, and have the same meaning when used for
materialized views. See the descriptions for <xref linkend="sql-altertable">
for details.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing materialized view.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column_name</replaceable></term>
<listitem>
<para>
Name of a new or existing column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_column_name</replaceable></term>
<listitem>
<para>
New name for an existing column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_owner</replaceable></term>
<listitem>
<para>
The user name of the new owner of the materialized view.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_name</replaceable></term>
<listitem>
<para>
The new name for the materialized view.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_schema</replaceable></term>
<listitem>
<para>
The new schema for the materialized view.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
To rename the materialized view <literal>foo</literal> to
<literal>bar</literal>:
<programlisting>
ALTER MATERIALIZED VIEW foo RENAME TO bar;
</programlisting></para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>ALTER MATERIALIZED VIEW</command> is a
<productname>PostgreSQL</productname> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-creatematerializedview"></member>
<member><xref linkend="sql-dropmaterializedview"></member>
<member><xref linkend="sql-refreshmaterializedview"></member>
</simplelist>
</refsect1>
</refentry>

2
doc/src/sgml/ref/comment.sgml
View File

@@ -38,6 +38,7 @@ COMMENT ON
FUNCTION <replaceable class="PARAMETER">function_name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) |
INDEX <replaceable class="PARAMETER">object_name</replaceable> |
LARGE OBJECT <replaceable class="PARAMETER">large_object_oid</replaceable> |
MATERIALIZED VIEW <replaceable class="PARAMETER">object_name</replaceable> |
OPERATOR <replaceable class="PARAMETER">operator_name</replaceable> (<replaceable class="PARAMETER">left_type</replaceable>, <replaceable class="PARAMETER">right_type</replaceable>) |
OPERATOR CLASS <replaceable class="PARAMETER">object_name</replaceable> USING <replaceable class="parameter">index_method</replaceable> |
OPERATOR FAMILY <replaceable class="PARAMETER">object_name</replaceable> USING <replaceable class="parameter">index_method</replaceable> |
@@ -279,6 +280,7 @@ COMMENT ON FUNCTION my_function (timestamp) IS 'Returns Roman Numeral';
COMMENT ON INDEX my_index IS 'Enforces uniqueness on employee ID';
COMMENT ON LANGUAGE plpython IS 'Python support for stored procedures';
COMMENT ON LARGE OBJECT 346344 IS 'Planning document';
COMMENT ON MATERIALIZED VIEW my_matview IS 'Summary of order history';
COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two texts';
COMMENT ON OPERATOR - (NONE, integer) IS 'Unary minus';
COMMENT ON OPERATOR CLASS int4ops USING btree IS '4 byte integer operators for btrees';

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

@@ -33,8 +33,8 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ <replaceable class="parameter">name</
<title>Description</title>
<para>
<command>CREATE INDEX</command> constructs an index
on the specified column(s) of the specified table.
<command>CREATE INDEX</command> constructs an index on the specified column(s)
of the specified relation, which can be a table or a materialized view.
Indexes are primarily used to enhance database performance (though
inappropriate use can result in slower performance).
</para>

154
doc/src/sgml/ref/create_materialized_view.sgml Normal file
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@@ -0,0 +1,154 @@
<!--
doc/src/sgml/ref/create_materialized_view.sgml
PostgreSQL documentation
-->
<refentry id="SQL-CREATEMATERIALIZEDVIEW">
<refmeta>
<refentrytitle>CREATE MATERIALIZED VIEW</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>CREATE MATERIALIZED VIEW</refname>
<refpurpose>define a new materialized view</refpurpose>
</refnamediv>
<indexterm zone="sql-creatematerializedview">
<primary>CREATE MATERIALIZED VIEW</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
CREATE [ UNLOGGED ] MATERIALIZED VIEW <replaceable>table_name</replaceable>
[ (<replaceable>column_name</replaceable> [, ...] ) ]
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) ]
[ TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
AS <replaceable>query</replaceable>
[ WITH [ NO ] DATA ]
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>CREATE MATERIALIZED VIEW</command> defines a materialized view of
a query. The query is executed and used to populate the view at the time
the command is issued (unless <command>WITH NO DATA</> is used) and may be
refreshed later using <command>REFRESH MATERIALIZED VIEW</command>.
</para>
<para>
<command>CREATE MATERIALIZED VIEW</command> is similar to
<command>CREATE TABLE AS</>, except that it also remembers the query used
to initialize the view, so that it can be refreshed later upon demand.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>UNLOGGED</></term>
<listitem>
<para>
If specified, the materialized view will be unlogged.
Refer to <xref linkend="sql-createtable"> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>table_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the materialized view to be
created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>column_name</replaceable></term>
<listitem>
<para>
The name of a column in the new materialized view. If column names are
not provided, they are taken from the output column names of the query.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] )</literal></term>
<listitem>
<para>
This clause specifies optional storage parameters for the new
materialized view; see <xref linkend="sql-createtable-storage-parameters"
endterm="sql-createtable-storage-parameters-title"> for more
information.
See <xref linkend="sql-createtable"> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable></literal></term>
<listitem>
<para>
The <replaceable class="PARAMETER">tablespace_name</replaceable> is the name
of the tablespace in which the new materialized view is to be created.
If not specified, <xref linkend="guc-default-tablespace"> is consulted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>query</replaceable></term>
<listitem>
<para>
A <xref linkend="sql-select">, <link linkend="sql-table">TABLE</link>,
or <xref linkend="sql-values"> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>WITH [ NO ] DATA</></term>
<listitem>
<para>
This clause specifies whether or not the materialized view should be
populated at creation time. If not, the materialized view will be
flagged as unscannable and cannot be queried until <command>REFRESH
MATERIALIZED VIEW</> is used.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>CREATE MATERIALIZED VIEW</command> is a
<productname>PostgreSQL</productname> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-altermaterializedview"></member>
<member><xref linkend="sql-createtableas"></member>
<member><xref linkend="sql-createview"></member>
<member><xref linkend="sql-dropmaterializedview"></member>
<member><xref linkend="sql-refreshmaterializedview"></member>
</simplelist>
</refsect1>
</refentry>

1
doc/src/sgml/ref/create_table_as.sgml
View File

@@ -340,6 +340,7 @@ CREATE TEMP TABLE films_recent WITH (OIDS) ON COMMIT DROP AS
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-creatematerializedview"></member>
<member><xref linkend="sql-createtable"></member>
<member><xref linkend="sql-execute"></member>
<member><xref linkend="sql-select"></member>

1
doc/src/sgml/ref/create_view.sgml
View File

@@ -379,6 +379,7 @@ CREATE VIEW <replaceable class="parameter">name</replaceable> [ ( <replaceable c
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-creatematerializedview"></member>
<member><xref linkend="sql-alterview"></member>
<member><xref linkend="sql-dropview"></member>
</simplelist>

114
doc/src/sgml/ref/drop_materialized_view.sgml Normal file
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@@ -0,0 +1,114 @@
<!--
doc/src/sgml/ref/drop_materialized_view.sgml
PostgreSQL documentation
-->
<refentry id="SQL-DROPMATERIALIZEDVIEW">
<refmeta>
<refentrytitle>DROP MATERIALIZED VIEW</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>DROP MATERIALIZED VIEW</refname>
<refpurpose>remove a materialized view</refpurpose>
</refnamediv>
<indexterm zone="sql-dropmaterializedview">
<primary>DROP MATERIALIZED VIEW</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
DROP MATERIALIZED VIEW [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>DROP MATERIALIZED VIEW</command> drops an existing materialized
view. To execute this command you must be the owner of the materialized
view.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF EXISTS</literal></term>
<listitem>
<para>
Do not throw an error if the materialized view 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 (optionally schema-qualified) of the materialized view to
remove.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the materialized view (such as
other materialized views, or regular views).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Refuse to drop the materialized view if any objects depend on it. This
is the default.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
This command will remove the materialized view called
<literal>order_summary</literal>:
<programlisting>
DROP MATERIALIZED VIEW order_summary;
</programlisting></para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>DROP MATERIALIZED VIEW</command> is a
<productname>PostgreSQL</productname> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-creatematerializedview"></member>
<member><xref linkend="sql-altermaterializedview"></member>
<member><xref linkend="sql-refreshmaterializedview"></member>
</simplelist>
</refsect1>
</refentry>

113
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@@ -0,0 +1,113 @@
<!--
doc/src/sgml/ref/refresh_materialized_view.sgml
PostgreSQL documentation
-->
<refentry id="SQL-REFRESHMATERIALIZEDVIEW">
<refmeta>
<refentrytitle>REFRESH MATERIALIZED VIEW</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>REFRESH MATERIALIZED VIEW</refname>
<refpurpose>replace the contents of a materialized view</refpurpose>
</refnamediv>
<indexterm zone="sql-refreshmaterializedview">
<primary>REFRESH MATERIALIZED VIEW</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
REFRESH MATERIALIZED VIEW <replaceable class="PARAMETER">name</replaceable>
[ WITH [ NO ] DATA ]
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>REFRESH MATERIALIZED VIEW</command> completely replaces the
contents of a materialized view. The old contents are discarded. If
<literal>WITH DATA</literal> is specified (or defaults) the backing query
is executed to provide the new data, and the materialized view is left in a
scannable state. If <literal>WITH NO DATA</literal> is specified no new
data is generated and the materialized view is left in an unscannable
state.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the materialized view to
refresh.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
While the default index for future
<xref linkend="SQL-CLUSTER">
operations is retained, <command>REFRESH MATERIALIZED VIEW</> does not
order the generated rows based on this property. If you want the data
to be ordered upon generation, you must use an <literal>ORDER BY</>
clause in the backing query.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
This command will replace the contents of the materialized view called
<literal>order_summary</literal> using the query from the materialized
view's definition, and leave it in a scannable state:
<programlisting>
REFRESH MATERIALIZED VIEW order_summary;
</programlisting>
</para>
<para>
This command will free storage associated with the materialized view
<literal>annual_statistics_basis</literal> and leave it in an unscannable
state:
<programlisting>
REFRESH MATERIALIZED VIEW annual_statistics_basis WITH NO DATA;
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<command>REFRESH MATERIALIZED VIEW</command> is a
<productname>PostgreSQL</productname> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-creatematerializedview"></member>
<member><xref linkend="sql-altermaterializedview"></member>
<member><xref linkend="sql-dropmaterializedview"></member>
</simplelist>
</refsect1>
</refentry>

1
doc/src/sgml/ref/security_label.sgml
View File

@@ -32,6 +32,7 @@ SECURITY LABEL [ FOR <replaceable class="PARAMETER">provider</replaceable> ] ON
FOREIGN TABLE <replaceable class="PARAMETER">object_name</replaceable>
FUNCTION <replaceable class="PARAMETER">function_name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) |
LARGE OBJECT <replaceable class="PARAMETER">large_object_oid</replaceable> |
MATERIALIZED VIEW <replaceable class="PARAMETER">object_name</replaceable> |
[ PROCEDURAL ] LANGUAGE <replaceable class="PARAMETER">object_name</replaceable> |
ROLE <replaceable class="PARAMETER">object_name</replaceable> |
SCHEMA <replaceable class="PARAMETER">object_name</replaceable> |

4
doc/src/sgml/reference.sgml
View File

@@ -49,6 +49,7 @@
&alterIndex;
&alterLanguage;
&alterLargeObject;
&alterMaterializedView;
&alterOperator;
&alterOperatorClass;
&alterOperatorFamily;
@@ -91,6 +92,7 @@
&createGroup;
&createIndex;
&createLanguage;
&createMaterializedView;
&createOperator;
&createOperatorClass;
&createOperatorFamily;
@@ -130,6 +132,7 @@
&dropGroup;
&dropIndex;
&dropLanguage;
&dropMaterializedView;
&dropOperator;
&dropOperatorClass;
&dropOperatorFamily;
@@ -164,6 +167,7 @@
&prepare;
&prepareTransaction;
&reassignOwned;
&refreshMaterializedView;
&reindex;
&releaseSavepoint;
&reset;

200
doc/src/sgml/rules.sgml
View File

@@ -893,6 +893,206 @@ SELECT t1.a, t2.b, t1.ctid FROM t1, t2 WHERE t1.a = t2.a;
</sect1>
<sect1 id="rules-materializedviews">
<title>Materialized Views</title>
<indexterm zone="rules-materializedviews">
<primary>rule</primary>
<secondary>and materialized views</secondary>
</indexterm>
<indexterm zone="rules-materializedviews">
<primary>materialized view</>
<secondary>implementation through rules</>
</indexterm>
<indexterm zone="rules-materializedviews">
<primary>view</>
<secondary>materialized</>
</indexterm>
<para>
Materialized views in <productname>PostgreSQL</productname> use the
rule system like views do, but persist the results in a table-like form.
The main differences between:
<programlisting>
CREATE MATERIALIZED VIEW mymatview AS SELECT * FROM mytab;
</programlisting>
and:
<programlisting>
CREATE TABLE mymatview AS SELECT * FROM mytab;
</programlisting>
are that the materialized view cannot subsequently be directly updated
and that the query used to create the materialized view is stored in
exactly the same way that a view's query is stored, so that fresh data
can be generated for the materialized view with:
<programlisting>
REFRESH MATERIALIZED VIEW mymatview;
</programlisting>
The information about a materialized view in the
<productname>PostgreSQL</productname> system catalogs is exactly
the same as it is for a table or view. So for the parser, a
materialized view is a relation, just like a table or a view. When
a materialized view is referenced in a query, the data is returned
directly from the materialized view, like from a table; the rule is
only used for populating the materialized view.
</para>
<para>
While access to the data stored in a materialized view is often much
faster than accessing the underlying tables directly or through a view,
the data is not always current; yet sometimes current data is not needed.
Consider a table which records sales:
<programlisting>
CREATE TABLE invoice (
invoice_no integer PRIMARY KEY,
seller_no integer, -- ID of salesperson
invoice_date date, -- date of sale
invoice_amt numeric(13,2) -- amount of sale
);
</programlisting>
If people want to be able to quickly graph historical sales data, they
might want to summarize, and they may not care about the incomplete data
for the current date:
<programlisting>
CREATE MATERIALIZED VIEW sales_summary AS
SELECT
seller_no,
invoice_date,
sum(invoice_amt)::numeric(13,2) as sales_amt
FROM invoice
WHERE invoice_date < CURRENT_DATE
GROUP BY
seller_no,
invoice_date
ORDER BY
seller_no,
invoice_date;
CREATE UNIQUE INDEX sales_summary_seller
ON sales_summary (seller_no, invoice_date);
</programlisting>
This materialized view might be useful for displaying a graph in the
dashboard created for salespeople. A job could be scheduled to update
the statistics each night using this SQL statement:
<programlisting>
REFRESH MATERIALIZED VIEW sales_summary;
</programlisting>
</para>
<para>
Another use for a materialized view is to allow faster access to data
brought across from a remote system, through a foreign data wrapper.
A simple example using <literal>file_fdw</literal> is below, with timings,
but since this is using cache on the local system the performance
difference on a foreign data wrapper to a remote system could be greater.
Setup:
<programlisting>
CREATE EXTENSION file_fdw;
CREATE SERVER local_file FOREIGN DATA WRAPPER file_fdw ;
CREATE FOREIGN TABLE words (word text NOT NULL)
SERVER local_file
OPTIONS (filename '/etc/dictionaries-common/words');
CREATE MATERIALIZED VIEW wrd AS SELECT * FROM words;
CREATE UNIQUE INDEX wrd_word ON wrd (word);
CREATE EXTENSION pg_trgm ;
CREATE INDEX wrd_trgm ON wrd USING gist (word gist_trgm_ops);
VACUUM ANALYZE wrd;
</programlisting>
Now let's spell-check a word. Using <literal>file_fdw</literal> directly:
<programlisting>
SELECT count(*) FROM words WHERE word = 'caterpiler';
count
-------
0
(1 row)
</programlisting>
The plan is:
<programlisting>
Aggregate (cost=4125.19..4125.20 rows=1 width=0) (actual time=26.013..26.014 rows=1 loops=1)
-> Foreign Scan on words (cost=0.00..4124.70 rows=196 width=0) (actual time=26.011..26.011 rows=0 loops=1)
Filter: (word = 'caterpiler'::text)
Rows Removed by Filter: 99171
Foreign File: /etc/dictionaries-common/words
Foreign File Size: 938848
Total runtime: 26.081 ms
</programlisting>
If the materialized view is used instead, the query is much faster:
<programlisting>
Aggregate (cost=4.44..4.45 rows=1 width=0) (actual time=0.074..0.074 rows=1 loops=1)
-> Index Only Scan using wrd_word on wrd (cost=0.42..4.44 rows=1 width=0) (actual time=0.071..0.071 rows=0 loops=1)
Index Cond: (word = 'caterpiler'::text)
Heap Fetches: 0
Total runtime: 0.119 ms
</programlisting>
Either way, the word is spelled wrong, so let's look for what we might
have wanted. Again using <literal>file_fdw</literal>:
<programlisting>
SELECT word FROM words ORDER BY word <-> 'caterpiler' LIMIT 10;
word
---------------
cater
caterpillar
Caterpillar
caterpillars
caterpillar's
Caterpillar's
caterer
caterer's
caters
catered
(10 rows)
</programlisting>
<programlisting>
Limit (cost=2195.70..2195.72 rows=10 width=32) (actual time=218.904..218.906 rows=10 loops=1)
-> Sort (cost=2195.70..2237.61 rows=16765 width=32) (actual time=218.902..218.904 rows=10 loops=1)
Sort Key: ((word <-> 'caterpiler'::text))
Sort Method: top-N heapsort Memory: 25kB
-> Foreign Scan on words (cost=0.00..1833.41 rows=16765 width=32) (actual time=0.046..200.965 rows=99171 loops=1)
Foreign File: /etc/dictionaries-common/words
Foreign File Size: 938848
Total runtime: 218.966 ms
</programlisting>
Using the materialized view:
<programlisting>
Limit (cost=0.28..1.02 rows=10 width=9) (actual time=24.916..25.079 rows=10 loops=1)
-> Index Scan using wrd_trgm on wrd (cost=0.28..7383.70 rows=99171 width=9) (actual time=24.914..25.076 rows=10 loops=1)
Order By: (word <-> 'caterpiler'::text)
Total runtime: 25.884 ms
</programlisting>
If you can tolerate periodic update of the remote data to the local
database, the performance benefit can be substantial.
</para>
</sect1>
<sect1 id="rules-update">
<title>Rules on <command>INSERT</>, <command>UPDATE</>, and <command>DELETE</></title>