Support unlogged tables.

The contents of an unlogged table are WAL-logged; thus, they are not
available on standby servers and are truncated whenever the database
system enters recovery.  Indexes on unlogged tables are also unlogged.
Unlogged GiST indexes are not currently supported.

7 files changed, 86 insertions, 5 deletions

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 9fa20cfeee9..0eeb499207e 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1644,7 +1644,8 @@
       <entry><type>bool</type></entry>
       <entry></entry>
       <entry>
-       <literal>p</> = permanent table, <literal>t</> = temporary table
+       <literal>p</> = permanent table, <literal>u</> = unlogged table,
+       <literal>t</> = temporary table
       </entry>
      </row>
 
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml
index c4eb59f7be7..51e70e92006 100644
--- a/doc/src/sgml/indexam.sgml
+++ b/doc/src/sgml/indexam.sgml
@@ -167,6 +167,17 @@ ambuild (Relation heapRelation,
 
   <para>
 <programlisting>
+void
+ambuildempty (Relation indexRelation);
+</programlisting>
+   Build an empty index, and write it to the initialization fork (INIT_FORKNUM)
+   of the given relation.  This method is called only for unlogged tables; the
+   empty index written to the initialization fork will be copied over the main
+   relation fork on each server restart.
+  </para>
+
+  <para>
+<programlisting>
 bool
 aminsert (Relation indexRelation,
           Datum *values,
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index bc5dff03296..efb4b1aca18 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
+CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
   { <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
     | <replaceable>table_constraint</replaceable>
     | LIKE <replaceable>parent_table</replaceable> [ <replaceable>like_option</replaceable> ... ] }
@@ -32,7 +32,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <repl
 [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
 [ TABLESPACE <replaceable class="PARAMETER">tablespace</replaceable> ]
 
-CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable>
+CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable>
     OF <replaceable class="PARAMETER">type_name</replaceable> [ (
   { <replaceable class="PARAMETER">column_name</replaceable> WITH OPTIONS [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
     | <replaceable>table_constraint</replaceable> }
@@ -165,6 +165,23 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <repl
    </varlistentry>
 
    <varlistentry>
+    <term><literal>UNLOGGED</></term>
+    <listitem>
+     <para>
+      If specified, the table is created as an unlogged table.  Data written
+      to unlogged tables is not written to the write-ahead log (see <xref
+      linkend="wal">), which makes them considerably faster than ordinary
+      tables.  However, they are not crash-safe: an unlogged table is
+      automatically truncated after a crash or unclean shutdown.  The contents
+      of an unlogged table are also not replicated to standby servers.
+      Any indexes created on an unlogged table are automatically unlogged as
+      well; however, unlogged <link linkend="GiST">GiST indexes</link> are
+      currently not supported and cannot be created on an unlogged table.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>IF NOT EXISTS</></term>
     <listitem>
      <para>
diff --git a/doc/src/sgml/ref/create_table_as.sgml b/doc/src/sgml/ref/create_table_as.sgml
index 3a256d1aaed..ff71078d1e2 100644
--- a/doc/src/sgml/ref/create_table_as.sgml
+++ b/doc/src/sgml/ref/create_table_as.sgml
@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name</replaceable>
+CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE <replaceable>table_name</replaceable>
     [ (<replaceable>column_name</replaceable> [, ...] ) ]
     [ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
     [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
@@ -82,6 +82,16 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name
    </varlistentry>
 
    <varlistentry>
+    <term><literal>UNLOGGED</></term>
+    <listitem>
+     <para>
+      If specified, the table is created as an unlogged table.
+      Refer to <xref linkend="sql-createtable"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><replaceable>table_name</replaceable></term>
     <listitem>
      <para>
diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index fd13c0d9e75..b291a257ea7 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -670,6 +670,17 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--no-unlogged-table-data</option></term>
+      <listitem>
+       <para>
+        Do not dump the contents of unlogged tables.  This option has no
+        effect on whether or not the table definitions (schema) are dumped;
+        it only suppresses dumping the table data.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--quote-all-identifiers</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 39da0b29490..04e95e876d1 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -202,6 +202,17 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--no-unlogged-table-data</option></term>
+      <listitem>
+       <para>
+        Do not dump the contents of unlogged tables.  This option has no
+        effect on whether or not the table definitions (schema) are dumped;
+        it only suppresses dumping the table data.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>-r</option></term>
       <term><option>--roles-only</option></term>
       <listitem>
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index cda7f6452f5..430df4a8438 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -147,7 +147,9 @@ the relation.  The free space map is stored in a file named with the filenode
 number plus the suffix <literal>_fsm</>.  Tables also have a
 <firstterm>visibility map</>, stored in a fork with the suffix <literal>_vm</>,
 to track which pages are known to have no dead tuples.  The visibility map is
-described further in <xref linkend="storage-vm">.
+described further in <xref linkend="storage-vm">.  Unlogged tables and indexes
+have a third fork, known as the initialization fork, which is stored in a fork
+with the suffix <literal>_init</literal> (see <xref linkend="storage-init">).
 </para>
 
 <caution>
@@ -485,6 +487,24 @@ a bit is not set, it might or might not be true.
 
 </sect1>
 
+<sect1 id="storage-init">
+
+<title>The Initialization Fork</title>
+
+<indexterm>
+ <primary>Initialization Fork</primary>
+</indexterm>
+
+<para>
+Each unlogged table, and each index on an unlogged table, has an initialization
+fork.  The initialization fork is an empty table or index of the appropriate
+type.  When an unlogged table must be reset to empty due to a crash, the
+initialization fork is copied over the main fork, and any other forks are
+erased (they will be recreated automatically as needed).
+</para>
+
+</sect1>
+
 <sect1 id="storage-page-layout">
 
 <title>Database Page Layout</title>