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Add support for temporary replication slots
This allows creating temporary replication slots that are removed automatically at the end of the session or on error. From: Petr Jelinek <petr.jelinek@2ndquadrant.com>
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18 files changed

+237
-51
lines changed

18 files changed

+237
-51
lines changed

‎contrib/test_decoding/Makefile‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -39,7 +39,7 @@ submake-test_decoding:
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REGRESSCHECKS=ddl xact rewrite toast permissions decoding_in_xact \
4141
decoding_into_rel binary prepared replorigin time messages \
42-
spill
42+
spill slot
4343

4444
regresscheck: | submake-regress submake-test_decoding temp-install
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$(MKDIR_P) regression_output

‎contrib/test_decoding/expected/ddl.out‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -702,7 +702,7 @@ SELECT pg_drop_replication_slot('regression_slot');
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703703
/* check that the slot is gone */
704704
SELECT * FROM pg_replication_slots;
705-
slot_name | plugin | slot_type | datoid | database | active | active_pid | xmin | catalog_xmin | restart_lsn | confirmed_flush_lsn
706-
-----------+--------+-----------+--------+----------+--------+------------+------+--------------+-------------+---------------------
705+
slot_name | plugin | slot_type | datoid | database | temporary | active | active_pid | xmin | catalog_xmin | restart_lsn | confirmed_flush_lsn
706+
-----------+--------+-----------+--------+----------+-----------+--------+------------+------+--------------+-------------+---------------------
707707
(0 rows)
708708

‎contrib/test_decoding/expected/slot.out‎

Lines changed: 58 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,58 @@
1+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test_decoding');
2+
?column?
3+
----------
4+
init
5+
(1 row)
6+
7+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_t', 'test_decoding', true);
8+
?column?
9+
----------
10+
init
11+
(1 row)
12+
13+
SELECT pg_drop_replication_slot('regression_slot_p');
14+
pg_drop_replication_slot
15+
--------------------------
16+
17+
(1 row)
18+
19+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test_decoding', false);
20+
?column?
21+
----------
22+
init
23+
(1 row)
24+
25+
-- reconnect to clean temp slots
26+
\c
27+
SELECT pg_drop_replication_slot('regression_slot_p');
28+
pg_drop_replication_slot
29+
--------------------------
30+
31+
(1 row)
32+
33+
-- should fail because the temporary slot was dropped automatically
34+
SELECT pg_drop_replication_slot('regression_slot_t');
35+
ERROR: replication slot "regression_slot_t" does not exist
36+
-- test switching between slots in a session
37+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot1', 'test_decoding', true);
38+
?column?
39+
----------
40+
init
41+
(1 row)
42+
43+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot2', 'test_decoding', true);
44+
?column?
45+
----------
46+
init
47+
(1 row)
48+
49+
SELECT * FROM pg_logical_slot_get_changes('regression_slot1', NULL, NULL);
50+
location | xid | data
51+
----------+-----+------
52+
(0 rows)
53+
54+
SELECT * FROM pg_logical_slot_get_changes('regression_slot2', NULL, NULL);
55+
location | xid | data
56+
----------+-----+------
57+
(0 rows)
58+

‎contrib/test_decoding/sql/slot.sql‎

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test_decoding');
2+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_t', 'test_decoding', true);
3+
4+
SELECT pg_drop_replication_slot('regression_slot_p');
5+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test_decoding', false);
6+
7+
-- reconnect to clean temp slots
8+
\c
9+
10+
SELECT pg_drop_replication_slot('regression_slot_p');
11+
12+
-- should fail because the temporary slot was dropped automatically
13+
SELECT pg_drop_replication_slot('regression_slot_t');
14+
15+
16+
-- test switching between slots in a session
17+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot1', 'test_decoding', true);
18+
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot2', 'test_decoding', true);
19+
SELECT * FROM pg_logical_slot_get_changes('regression_slot1', NULL, NULL);
20+
SELECT * FROM pg_logical_slot_get_changes('regression_slot2', NULL, NULL);

‎doc/src/sgml/func.sgml‎

Lines changed: 12 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -18465,7 +18465,7 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
1846518465
<indexterm>
1846618466
<primary>pg_create_physical_replication_slot</primary>
1846718467
</indexterm>
18468-
<literal><function>pg_create_physical_replication_slot(<parameter>slot_name</parameter> <type>name</type> <optional>, <parameter>immediately_reserve</> <type>boolean</> </optional>)</function></literal>
18468+
<literal><function>pg_create_physical_replication_slot(<parameter>slot_name</parameter> <type>name</type> <optional>, <parameter>immediately_reserve</> <type>boolean</>, <parameter>temporary</> <type>boolean</></optional>)</function></literal>
1846918469
</entry>
1847018470
<entry>
1847118471
(<parameter>slot_name</parameter> <type>name</type>, <parameter>xlog_position</parameter> <type>pg_lsn</type>)
@@ -18478,7 +18478,11 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
1847818478
the <acronym>LSN</> is reserved on first connection from a streaming
1847918479
replication client. Streaming changes from a physical slot is only
1848018480
possible with the streaming-replication protocol &mdash;
18481-
see <xref linkend="protocol-replication">. This function corresponds
18481+
see <xref linkend="protocol-replication">. The optional third
18482+
parameter, <parameter>temporary</>, when set to true, specifies that
18483+
the slot should not be permanently stored to disk and is only meant
18484+
for use by current session. Temporary slots are also
18485+
released upon any error. This function corresponds
1848218486
to the replication protocol command <literal>CREATE_REPLICATION_SLOT
1848318487
... PHYSICAL</literal>.
1848418488
</entry>
@@ -18505,15 +18509,19 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
1850518509
<indexterm>
1850618510
<primary>pg_create_logical_replication_slot</primary>
1850718511
</indexterm>
18508-
<literal><function>pg_create_logical_replication_slot(<parameter>slot_name</parameter> <type>name</type>, <parameter>plugin</parameter> <type>name</type>)</function></literal>
18512+
<literal><function>pg_create_logical_replication_slot(<parameter>slot_name</parameter> <type>name</type>, <parameter>plugin</parameter> <type>name</type> <optional>, <parameter>temporary</> <type>boolean</></optional>)</function></literal>
1850918513
</entry>
1851018514
<entry>
1851118515
(<parameter>slot_name</parameter> <type>name</type>, <parameter>xlog_position</parameter> <type>pg_lsn</type>)
1851218516
</entry>
1851318517
<entry>
1851418518
Creates a new logical (decoding) replication slot named
1851518519
<parameter>slot_name</parameter> using the output plugin
18516-
<parameter>plugin</parameter>. A call to this function has the same
18520+
<parameter>plugin</parameter>. The optional third
18521+
parameter, <parameter>temporary</>, when set to true, specifies that
18522+
the slot should not be permanently stored to disk and is only meant
18523+
for use by current session. Temporary slots are also
18524+
released upon any error. A call to this function has the same
1851718525
effect as the replication protocol command
1851818526
<literal>CREATE_REPLICATION_SLOT ... LOGICAL</literal>.
1851918527
</entry>

‎doc/src/sgml/protocol.sgml‎

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1434,7 +1434,7 @@ The commands accepted in walsender mode are:
14341434
</varlistentry>
14351435

14361436
<varlistentry>
1437-
<term><literal>CREATE_REPLICATION_SLOT</literal> <replaceable class="parameter">slot_name</> { <literal>PHYSICAL</> [ <literal>RESERVE_WAL</> ] | <literal>LOGICAL</> <replaceable class="parameter">output_plugin</> }
1437+
<term><literal>CREATE_REPLICATION_SLOT</literal> <replaceable class="parameter">slot_name</> [ <literal>TEMPORARY</> ] { <literal>PHYSICAL</> [ <literal>RESERVE_WAL</> ] | <literal>LOGICAL</> <replaceable class="parameter">output_plugin</> }
14381438
<indexterm><primary>CREATE_REPLICATION_SLOT</primary></indexterm>
14391439
</term>
14401440
<listitem>
@@ -1464,6 +1464,17 @@ The commands accepted in walsender mode are:
14641464
</listitem>
14651465
</varlistentry>
14661466

1467+
<varlistentry>
1468+
<term><literal>TEMPORARY</></term>
1469+
<listitem>
1470+
<para>
1471+
Specify that this replication slot is a temporary one. Temporary
1472+
slots are not saved to disk and are automatically dropped on error
1473+
or when the session has finished.
1474+
</para>
1475+
</listitem>
1476+
</varlistentry>
1477+
14671478
<varlistentry>
14681479
<term><literal>RESERVE_WAL</></term>
14691480
<listitem>

‎src/backend/catalog/system_views.sql‎

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -726,6 +726,7 @@ CREATE VIEW pg_replication_slots AS
726726
L.slot_type,
727727
L.datoid,
728728
D.datname AS database,
729+
L.temporary,
729730
L.active,
730731
L.active_pid,
731732
L.xmin,
@@ -991,12 +992,22 @@ AS 'pg_logical_slot_peek_binary_changes';
991992

992993
CREATE OR REPLACE FUNCTION pg_create_physical_replication_slot(
993994
IN slot_name name, IN immediately_reserve boolean DEFAULT false,
995+
IN temporary boolean DEFAULT false,
994996
OUT slot_name name, OUT xlog_position pg_lsn)
995997
RETURNS RECORD
996998
LANGUAGE INTERNAL
997999
STRICT VOLATILE
9981000
AS 'pg_create_physical_replication_slot';
9991001

1002+
CREATE OR REPLACE FUNCTION pg_create_logical_replication_slot(
1003+
IN slot_name name, IN plugin name,
1004+
IN temporary boolean DEFAULT false,
1005+
OUT slot_name text, OUT xlog_position pg_lsn)
1006+
RETURNS RECORD
1007+
LANGUAGE INTERNAL
1008+
STRICT VOLATILE
1009+
AS 'pg_create_logical_replication_slot';
1010+
10001011
CREATE OR REPLACE FUNCTION
10011012
make_interval(years int4 DEFAULT 0, months int4 DEFAULT 0, weeks int4 DEFAULT 0,
10021013
days int4 DEFAULT 0, hours int4 DEFAULT 0, mins int4 DEFAULT 0,

‎src/backend/replication/repl_gram.y‎

Lines changed: 15 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -77,6 +77,7 @@ Node *replication_parse_result;
7777
%token K_LOGICAL
7878
%token K_SLOT
7979
%token K_RESERVE_WAL
80+
%token K_TEMPORARY
8081

8182
%type <node> command
8283
%type <node> base_backup start_replication start_logical_replication
@@ -89,7 +90,7 @@ Node *replication_parse_result;
8990
%type <defelt> plugin_opt_elem
9091
%type <node> plugin_opt_arg
9192
%type <str> opt_slot
92-
%type <boolval> opt_reserve_wal
93+
%type <boolval> opt_reserve_wal opt_temporary
9394

9495
%%
9596

@@ -183,24 +184,26 @@ base_backup_opt:
183184
;
184185

185186
create_replication_slot:
186-
/* CREATE_REPLICATION_SLOT slot PHYSICAL RESERVE_WAL */
187-
K_CREATE_REPLICATION_SLOT IDENT K_PHYSICAL opt_reserve_wal
187+
/* CREATE_REPLICATION_SLOT slot TEMPORARY PHYSICAL RESERVE_WAL */
188+
K_CREATE_REPLICATION_SLOT IDENT opt_temporary K_PHYSICAL opt_reserve_wal
188189
{
189190
CreateReplicationSlotCmd *cmd;
190191
cmd = makeNode(CreateReplicationSlotCmd);
191192
cmd->kind = REPLICATION_KIND_PHYSICAL;
192193
cmd->slotname = $2;
193-
cmd->reserve_wal = $4;
194+
cmd->temporary = $3;
195+
cmd->reserve_wal = $5;
194196
$$ = (Node *) cmd;
195197
}
196-
/* CREATE_REPLICATION_SLOT slot LOGICAL plugin */
197-
| K_CREATE_REPLICATION_SLOT IDENT K_LOGICAL IDENT
198+
/* CREATE_REPLICATION_SLOT slot TEMPORARY LOGICAL plugin */
199+
| K_CREATE_REPLICATION_SLOT IDENT opt_temporary K_LOGICAL IDENT
198200
{
199201
CreateReplicationSlotCmd *cmd;
200202
cmd = makeNode(CreateReplicationSlotCmd);
201203
cmd->kind = REPLICATION_KIND_LOGICAL;
202204
cmd->slotname = $2;
203-
cmd->plugin = $4;
205+
cmd->temporary = $3;
206+
cmd->plugin = $5;
204207
$$ = (Node *) cmd;
205208
}
206209
;
@@ -276,6 +279,11 @@ opt_reserve_wal:
276279
| /* EMPTY */ { $$ = false; }
277280
;
278281

282+
opt_temporary:
283+
K_TEMPORARY { $$ = true; }
284+
| /* EMPTY */ { $$ = false; }
285+
;
286+
279287
opt_slot:
280288
K_SLOT IDENT
281289
{ $$ = $2; }

‎src/backend/replication/repl_scanner.l‎

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Original file line numberDiff line numberDiff line change
@@ -98,6 +98,7 @@ PHYSICAL { return K_PHYSICAL; }
9898
RESERVE_WAL { return K_RESERVE_WAL; }
9999
LOGICAL { return K_LOGICAL; }
100100
SLOT { return K_SLOT; }
101+
TEMPORARY { return K_TEMPORARY; }
101102

102103
"," { return ','; }
103104
";" { return ';'; }

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