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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.
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‎doc/src/sgml/catalogs.sgml

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@@ -1644,7 +1644,8 @@
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<entry><type>bool</type></entry>
16451645
<entry></entry>
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<entry>
1647-
<literal>p</> = permanent table, <literal>t</> = temporary table
1647+
<literal>p</> = permanent table, <literal>u</> = unlogged table,
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<literal>t</> = temporary table
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</entry>
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</row>
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‎doc/src/sgml/indexam.sgml

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@@ -167,6 +167,17 @@ ambuild (Relation heapRelation,
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<para>
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<programlisting>
170+
void
171+
ambuildempty (Relation indexRelation);
172+
</programlisting>
173+
Build an empty index, and write it to the initialization fork (INIT_FORKNUM)
174+
of the given relation. This method is called only for unlogged tables; the
175+
empty index written to the initialization fork will be copied over the main
176+
relation fork on each server restart.
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</para>
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<para>
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<programlisting>
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bool
171182
aminsert (Relation indexRelation,
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Datum *values,

‎doc/src/sgml/ref/create_table.sgml

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@@ -21,7 +21,7 @@ PostgreSQL documentation
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<refsynopsisdiv>
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<synopsis>
24-
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
24+
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
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{ <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
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| <replaceable>table_constraint</replaceable>
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| LIKE <replaceable>parent_table</replaceable> [ <replaceable>like_option</replaceable> ... ] }
@@ -32,7 +32,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <repl
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[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
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[ TABLESPACE <replaceable class="PARAMETER">tablespace</replaceable> ]
3434

35-
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable>
35+
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable>
3636
OF <replaceable class="PARAMETER">type_name</replaceable> [ (
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{ <replaceable class="PARAMETER">column_name</replaceable> WITH OPTIONS [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
3838
| <replaceable>table_constraint</replaceable> }
@@ -164,6 +164,23 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE [ IF NOT EXISTS ] <repl
164164
</listitem>
165165
</varlistentry>
166166

167+
<varlistentry>
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<term><literal>UNLOGGED</></term>
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<listitem>
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<para>
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If specified, the table is created as an unlogged table. Data written
172+
to unlogged tables is not written to the write-ahead log (see <xref
173+
linkend="wal">), which makes them considerably faster than ordinary
174+
tables. However, they are not crash-safe: an unlogged table is
175+
automatically truncated after a crash or unclean shutdown. The contents
176+
of an unlogged table are also not replicated to standby servers.
177+
Any indexes created on an unlogged table are automatically unlogged as
178+
well; however, unlogged <link linkend="GiST">GiST indexes</link> are
179+
currently not supported and cannot be created on an unlogged table.
180+
</para>
181+
</listitem>
182+
</varlistentry>
183+
167184
<varlistentry>
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<term><literal>IF NOT EXISTS</></term>
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<listitem>

‎doc/src/sgml/ref/create_table_as.sgml

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@@ -21,7 +21,7 @@ PostgreSQL documentation
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2222
<refsynopsisdiv>
2323
<synopsis>
24-
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name</replaceable>
24+
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE <replaceable>table_name</replaceable>
2525
[ (<replaceable>column_name</replaceable> [, ...] ) ]
2626
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
2727
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
@@ -81,6 +81,16 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name
8181
</listitem>
8282
</varlistentry>
8383

84+
<varlistentry>
85+
<term><literal>UNLOGGED</></term>
86+
<listitem>
87+
<para>
88+
If specified, the table is created as an unlogged table.
89+
Refer to <xref linkend="sql-createtable"> for details.
90+
</para>
91+
</listitem>
92+
</varlistentry>
93+
8494
<varlistentry>
8595
<term><replaceable>table_name</replaceable></term>
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<listitem>

‎doc/src/sgml/ref/pg_dump.sgml

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@@ -669,6 +669,17 @@ PostgreSQL documentation
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--no-unlogged-table-data</option></term>
674+
<listitem>
675+
<para>
676+
Do not dump the contents of unlogged tables. This option has no
677+
effect on whether or not the table definitions (schema) are dumped;
678+
it only suppresses dumping the table data.
679+
</para>
680+
</listitem>
681+
</varlistentry>
682+
672683
<varlistentry>
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<term><option>--quote-all-identifiers</></term>
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<listitem>

‎doc/src/sgml/ref/pg_dumpall.sgml

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@@ -201,6 +201,17 @@ PostgreSQL documentation
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</listitem>
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</varlistentry>
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204+
<varlistentry>
205+
<term><option>--no-unlogged-table-data</option></term>
206+
<listitem>
207+
<para>
208+
Do not dump the contents of unlogged tables. This option has no
209+
effect on whether or not the table definitions (schema) are dumped;
210+
it only suppresses dumping the table data.
211+
</para>
212+
</listitem>
213+
</varlistentry>
214+
204215
<varlistentry>
205216
<term><option>-r</option></term>
206217
<term><option>--roles-only</option></term>

‎doc/src/sgml/storage.sgml

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Original file line numberDiff line numberDiff line change
@@ -147,7 +147,9 @@ the relation. The free space map is stored in a file named with the filenode
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number plus the suffix <literal>_fsm</>. Tables also have a
148148
<firstterm>visibility map</>, stored in a fork with the suffix <literal>_vm</>,
149149
to track which pages are known to have no dead tuples. The visibility map is
150-
described further in <xref linkend="storage-vm">.
150+
described further in <xref linkend="storage-vm">. Unlogged tables and indexes
151+
have a third fork, known as the initialization fork, which is stored in a fork
152+
with the suffix <literal>_init</literal> (see <xref linkend="storage-init">).
151153
</para>
152154

153155
<caution>
@@ -485,6 +487,24 @@ a bit is not set, it might or might not be true.
485487

486488
</sect1>
487489

490+
<sect1 id="storage-init">
491+
492+
<title>The Initialization Fork</title>
493+
494+
<indexterm>
495+
<primary>Initialization Fork</primary>
496+
</indexterm>
497+
498+
<para>
499+
Each unlogged table, and each index on an unlogged table, has an initialization
500+
fork. The initialization fork is an empty table or index of the appropriate
501+
type. When an unlogged table must be reset to empty due to a crash, the
502+
initialization fork is copied over the main fork, and any other forks are
503+
erased (they will be recreated automatically as needed).
504+
</para>
505+
506+
</sect1>
507+
488508
<sect1 id="storage-page-layout">
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490510
<title>Database Page Layout</title>

‎src/backend/access/gin/gininsert.c

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Original file line numberDiff line numberDiff line change
@@ -19,6 +19,7 @@
1919
#include "catalog/index.h"
2020
#include "miscadmin.h"
2121
#include "storage/bufmgr.h"
22+
#include "storage/smgr.h"
2223
#include "storage/indexfsm.h"
2324
#include "utils/memutils.h"
2425

@@ -411,6 +412,47 @@ ginbuild(PG_FUNCTION_ARGS)
411412
PG_RETURN_POINTER(result);
412413
}
413414

415+
/*
416+
* ginbuildempty() -- build an empty gin index in the initialization fork
417+
*/
418+
Datum
419+
ginbuildempty(PG_FUNCTION_ARGS)
420+
{
421+
Relation index = (Relation) PG_GETARG_POINTER(0);
422+
Buffer RootBuffer,
423+
MetaBuffer;
424+
425+
/* An empty GIN index has two pages. */
426+
MetaBuffer =
427+
ReadBufferExtended(index, INIT_FORKNUM, P_NEW, RBM_NORMAL, NULL);
428+
LockBuffer(MetaBuffer, BUFFER_LOCK_EXCLUSIVE);
429+
RootBuffer =
430+
ReadBufferExtended(index, INIT_FORKNUM, P_NEW, RBM_NORMAL, NULL);
431+
LockBuffer(RootBuffer, BUFFER_LOCK_EXCLUSIVE);
432+
433+
/* Initialize both pages, mark them dirty, unlock and release buffer. */
434+
START_CRIT_SECTION();
435+
GinInitMetabuffer(MetaBuffer);
436+
MarkBufferDirty(MetaBuffer);
437+
GinInitBuffer(RootBuffer, GIN_LEAF);
438+
MarkBufferDirty(RootBuffer);
439+
440+
/* XLOG the new pages */
441+
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
442+
BufferGetBlockNumber(MetaBuffer),
443+
BufferGetPage(MetaBuffer));
444+
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
445+
BufferGetBlockNumber(RootBuffer),
446+
BufferGetPage(RootBuffer));
447+
END_CRIT_SECTION();
448+
449+
/* Unlock and release the buffers. */
450+
UnlockReleaseBuffer(MetaBuffer);
451+
UnlockReleaseBuffer(RootBuffer);
452+
453+
PG_RETURN_VOID();
454+
}
455+
414456
/*
415457
* Inserts value during normal insertion
416458
*/

‎src/backend/access/gist/gist.c

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Original file line numberDiff line numberDiff line change
@@ -218,6 +218,19 @@ gistbuildCallback(Relation index,
218218
MemoryContextReset(buildstate->tmpCtx);
219219
}
220220

221+
/*
222+
* gistbuildempty() -- build an empty gist index in the initialization fork
223+
*/
224+
Datum
225+
gistbuildempty(PG_FUNCTION_ARGS)
226+
{
227+
ereport(ERROR,
228+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
229+
errmsg("unlogged GIST indexes are not supported")));
230+
231+
PG_RETURN_VOID();
232+
}
233+
221234
/*
222235
* gistinsert -- wrapper for GiST tuple insertion.
223236
*

‎src/backend/access/hash/hash.c

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -69,7 +69,7 @@ hashbuild(PG_FUNCTION_ARGS)
6969
estimate_rel_size(heap, NULL, &relpages, &reltuples);
7070

7171
/* Initialize the hash index metadata page and initial buckets */
72-
num_buckets = _hash_metapinit(index, reltuples);
72+
num_buckets = _hash_metapinit(index, reltuples, MAIN_FORKNUM);
7373

7474
/*
7575
* If we just insert the tuples into the index in scan order, then
@@ -113,6 +113,19 @@ hashbuild(PG_FUNCTION_ARGS)
113113
PG_RETURN_POINTER(result);
114114
}
115115

116+
/*
117+
* hashbuildempty() -- build an empty hash index in the initialization fork
118+
*/
119+
Datum
120+
hashbuildempty(PG_FUNCTION_ARGS)
121+
{
122+
Relation index = (Relation) PG_GETARG_POINTER(0);
123+
124+
_hash_metapinit(index, 0, INIT_FORKNUM);
125+
126+
PG_RETURN_VOID();
127+
}
128+
116129
/*
117130
* Per-tuple callback from IndexBuildHeapScan
118131
*/

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