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Add option to modify sync commit per subscription 

This also changes default behaviour of subscription workers to
synchronous_commit = off.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
This commit is contained in:
Peter Eisentraut 2017-04-14 13:58:46 -04:00
parent 25371a72b9
commit 887227a1cc
13 changed files with 145 additions and 33 deletions
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10
doc/src/sgml/catalogs.sgml
View File

@ -6530,6 +6530,16 @@
<entry>If true, the subscription is enabled and should be replicating.</entry>
</row>
<row>
<entry><structfield>subsynccommit</structfield></entry>
<entry><type>text</type></entry>
<entry></entry>
<entry>
Contains the value of the <varname>synchronous_commit</varname>
setting for the subscription workers.
</entry>
</row>
<row>
<entry><structfield>subconninfo</structfield></entry>
<entry><type>text</type></entry>

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

@ -26,6 +26,7 @@ ALTER SUBSCRIPTION <replaceable class="PARAMETER">name</replaceable> WITH ( <rep
<phrase>where <replaceable class="PARAMETER">suboption</replaceable> can be:</phrase>
SLOT NAME = <replaceable class="PARAMETER">slot_name</replaceable>
| SYNCHRONOUS_COMMIT = <replaceable class="PARAMETER">synchronous_commit</replaceable>
ALTER SUBSCRIPTION <replaceable class="PARAMETER">name</replaceable> SET PUBLICATION <replaceable class="PARAMETER">publication_name</replaceable> [, ...] { REFRESH WITH ( <replaceable class="PARAMETER">puboption</replaceable> [, ... ] ) | NOREFRESH }
ALTER SUBSCRIPTION <replaceable class="PARAMETER">name</replaceable> REFRESH PUBLICATION WITH ( <replaceable class="PARAMETER">puboption</replaceable> [, ... ] )
@ -91,6 +92,7 @@ ALTER SUBSCRIPTION <replaceable class="PARAMETER">name</replaceable> DISABLE
<varlistentry>
<term><literal>CONNECTION '<replaceable class="parameter">conninfo</replaceable>'</literal></term>
<term><literal>SLOT NAME = <replaceable class="parameter">slot_name</replaceable></literal></term>
<term><literal>SYNCHRONOUS_COMMIT = <replaceable class="PARAMETER">synchronous_commit</replaceable></literal></term>
<listitem>
<para>
These clauses alter properties originally set by

31
doc/src/sgml/ref/create_subscription.sgml
View File

@ -32,6 +32,7 @@ CREATE SUBSCRIPTION <replaceable class="PARAMETER">subscription_name</replaceabl
| CREATE SLOT | NOCREATE SLOT
| SLOT NAME = <replaceable class="PARAMETER">slot_name</replaceable>
| COPY DATA | NOCOPY DATA
| SYNCHRONOUS_COMMIT = <replaceable class="PARAMETER">synchronous_commit</replaceable>
| NOCONNECT
</synopsis>
</refsynopsisdiv>
@ -147,6 +148,36 @@ CREATE SUBSCRIPTION <replaceable class="PARAMETER">subscription_name</replaceabl
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SYNCHRONOUS_COMMIT = <replaceable class="PARAMETER">synchronous_commit</replaceable></literal></term>
<listitem>
<para>
The value of this parameter overrides the
<xref linkend="guc-synchronous-commit"> setting. The default value is
<literal>off</literal>.
</para>
<para>
It is safe to use <literal>off</literal> for logical replication: If the
subscriber loses transactions because of missing synchronization, the
data will be resent from the publisher.
</para>
<para>
A different setting might be appropriate when doing synchronous logical
replication. The logical replication workers report the positions of
writes and flushes to the publisher, and when using synchronous
replication, the publisher will wait for the actual flush. This means
that setting <literal>SYNCHRONOUS_COMMIT</literal> for the subscriber
to <literal>off</literal> when the subscription is used for synchronous
replication might increase the latency for <command>COMMIT</command> on
the publisher. In this scenario, it can be advantageous to set
<literal>SYNCHRONOUS_COMMIT</literal> to <literal>local</literal> or
higher.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>NOCONNECT</literal></term>
<listitem>

8
src/backend/catalog/pg_subscription.c
View File

@ -85,6 +85,14 @@ GetSubscription(Oid subid, bool missing_ok)
Assert(!isnull);
sub->slotname = pstrdup(NameStr(*DatumGetName(datum)));
/* Get synccommit */
datum = SysCacheGetAttr(SUBSCRIPTIONOID,
tup,
Anum_pg_subscription_subsynccommit,
&isnull);
Assert(!isnull);
sub->synccommit = TextDatumGetCString(datum);
/* Get publications */
datum = SysCacheGetAttr(SUBSCRIPTIONOID,
tup,

54
src/backend/commands/subscriptioncmds.c
View File

@ -44,6 +44,7 @@
#include "storage/lmgr.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
@ -60,7 +61,7 @@ static List *fetch_table_list(WalReceiverConn *wrconn, List *publications);
static void
parse_subscription_options(List *options, bool *connect, bool *enabled_given,
bool *enabled, bool *create_slot, char **slot_name,
bool *copy_data)
bool *copy_data, char **synchronous_commit)
{
ListCell *lc;
bool connect_given = false;
@ -80,6 +81,8 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
*slot_name = NULL;
if (copy_data)
*copy_data = true;
if (synchronous_commit)
*synchronous_commit = NULL;
/* Parse options */
foreach (lc, options)
@ -165,6 +168,21 @@ parse_subscription_options(List *options, bool *connect, bool *enabled_given,
copy_data_given = true;
*copy_data = !defGetBoolean(defel);
}
else if (strcmp(defel->defname, "synchronous_commit") == 0 &&
synchronous_commit)
{
if (*synchronous_commit)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
*synchronous_commit = defGetString(defel);
/* Test if the given value is valid for synchronous_commit GUC. */
(void) set_config_option("synchronous_commit", *synchronous_commit,
PGC_BACKEND, PGC_S_TEST, GUC_ACTION_SET,
false, 0, false);
}
else
elog(ERROR, "unrecognized option: %s", defel->defname);
}
@ -269,6 +287,7 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
bool enabled_given;
bool enabled;
bool copy_data;
char *synchronous_commit;
char *conninfo;
char *slotname;
char originname[NAMEDATALEN];
@ -280,7 +299,8 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
* Connection and publication should not be specified here.
*/
parse_subscription_options(stmt->options, &connect, &enabled_given,
&enabled, &create_slot, &slotname, &copy_data);
&enabled, &create_slot, &slotname, &copy_data,
&synchronous_commit);
/*
* Since creating a replication slot is not transactional, rolling back
@ -311,6 +331,9 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
if (slotname == NULL)
slotname = stmt->subname;
/* The default for synchronous_commit of subscriptions is off. */
if (synchronous_commit == NULL)
synchronous_commit = "off";
conninfo = stmt->conninfo;
publications = stmt->publication;
@ -334,6 +357,8 @@ CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
CStringGetTextDatum(conninfo);
values[Anum_pg_subscription_subslotname - 1] =
DirectFunctionCall1(namein, CStringGetDatum(slotname));
values[Anum_pg_subscription_subsynccommit - 1] =
CStringGetTextDatum(synchronous_commit);
values[Anum_pg_subscription_subpublications - 1] =
publicationListToArray(publications);
@ -582,13 +607,24 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
case ALTER_SUBSCRIPTION_OPTIONS:
{
char *slot_name;
char *synchronous_commit;
parse_subscription_options(stmt->options, NULL, NULL, NULL,
NULL, &slot_name, NULL);
NULL, &slot_name, NULL,
&synchronous_commit);
values[Anum_pg_subscription_subslotname - 1] =
DirectFunctionCall1(namein, CStringGetDatum(slot_name));
replaces[Anum_pg_subscription_subslotname - 1] = true;
if (slot_name)
{
values[Anum_pg_subscription_subslotname - 1] =
DirectFunctionCall1(namein, CStringGetDatum(slot_name));
replaces[Anum_pg_subscription_subslotname - 1] = true;
}
if (synchronous_commit)
{
values[Anum_pg_subscription_subsynccommit - 1] =
CStringGetTextDatum(synchronous_commit);
replaces[Anum_pg_subscription_subsynccommit - 1] = true;
}
update_tuple = true;
break;
@ -601,7 +637,7 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
parse_subscription_options(stmt->options, NULL,
&enabled_given, &enabled, NULL,
NULL, NULL);
NULL, NULL, NULL);
Assert(enabled_given);
values[Anum_pg_subscription_subenabled - 1] =
@ -626,7 +662,7 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
Subscription *sub = GetSubscription(subid, false);
parse_subscription_options(stmt->options, NULL, NULL, NULL,
NULL, NULL, &copy_data);
NULL, NULL, &copy_data, NULL);
values[Anum_pg_subscription_subpublications - 1] =
publicationListToArray(stmt->publication);
@ -652,7 +688,7 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
Subscription *sub = GetSubscription(subid, false);
parse_subscription_options(stmt->options, NULL, NULL, NULL,
NULL, NULL, &copy_data);
NULL, NULL, &copy_data, NULL);
AlterSubscription_refresh(sub, copy_data);

6
src/backend/replication/logical/launcher.c
View File

@ -129,17 +129,13 @@ get_subscription_list(void)
*/
oldcxt = MemoryContextSwitchTo(resultcxt);
sub = (Subscription *) palloc(sizeof(Subscription));
sub = (Subscription *) palloc0(sizeof(Subscription));
sub->oid = HeapTupleGetOid(tup);
sub->dbid = subform->subdbid;
sub->owner = subform->subowner;
sub->enabled = subform->subenabled;
sub->name = pstrdup(NameStr(subform->subname));
/* We don't fill fields we are not interested in. */
sub->conninfo = NULL;
sub->slotname = NULL;
sub->publications = NIL;
res = lappend(res, sub);
MemoryContextSwitchTo(oldcxt);

8
src/backend/replication/logical/worker.c
View File

@ -1416,6 +1416,10 @@ reread_subscription(void)
MemoryContextSwitchTo(oldctx);
/* Change synchronous commit according to the user's wishes */
SetConfigOption("synchronous_commit", MySubscription->synccommit,
PGC_BACKEND, PGC_S_OVERRIDE);
if (started_tx)
CommitTransactionCommand();
@ -1485,6 +1489,10 @@ ApplyWorkerMain(Datum main_arg)
MySubscriptionValid = true;
MemoryContextSwitchTo(oldctx);
/* Setup synchronous commit according to the user's wishes */
SetConfigOption("synchronous_commit", MySubscription->synccommit,
PGC_BACKEND, PGC_S_OVERRIDE);
if (!MySubscription->enabled)
{
ereport(LOG,

11
src/bin/pg_dump/pg_dump.c
View File

@ -3683,6 +3683,7 @@ getSubscriptions(Archive *fout)
int i_rolname;
int i_subconninfo;
int i_subslotname;
int i_subsynccommit;
int i_subpublications;
int i,
ntups;
@ -3714,7 +3715,8 @@ getSubscriptions(Archive *fout)
appendPQExpBuffer(query,
"SELECT s.tableoid, s.oid, s.subname,"
"(%s s.subowner) AS rolname, "
" s.subconninfo, s.subslotname, s.subpublications "
" s.subconninfo, s.subslotname, s.subsynccommit, "
" s.subpublications "
"FROM pg_catalog.pg_subscription s "
"WHERE s.subdbid = (SELECT oid FROM pg_catalog.pg_database"
" WHERE datname = current_database())",
@ -3729,6 +3731,7 @@ getSubscriptions(Archive *fout)
i_rolname = PQfnumber(res, "rolname");
i_subconninfo = PQfnumber(res, "subconninfo");
i_subslotname = PQfnumber(res, "subslotname");
i_subsynccommit = PQfnumber(res, "subsynccommit");
i_subpublications = PQfnumber(res, "subpublications");
subinfo = pg_malloc(ntups * sizeof(SubscriptionInfo));
@ -3744,6 +3747,8 @@ getSubscriptions(Archive *fout)
subinfo[i].rolname = pg_strdup(PQgetvalue(res, i, i_rolname));
subinfo[i].subconninfo = pg_strdup(PQgetvalue(res, i, i_subconninfo));
subinfo[i].subslotname = pg_strdup(PQgetvalue(res, i, i_subslotname));
subinfo[i].subsynccommit =
pg_strdup(PQgetvalue(res, i, i_subsynccommit));
subinfo[i].subpublications =
pg_strdup(PQgetvalue(res, i, i_subpublications));
@ -3810,6 +3815,10 @@ dumpSubscription(Archive *fout, SubscriptionInfo *subinfo)
appendPQExpBuffer(query, " PUBLICATION %s WITH (NOCONNECT, SLOT NAME = ", publications->data);
appendStringLiteralAH(query, subinfo->subslotname, fout);
if (strcmp(subinfo->subsynccommit, "off") != 0)
appendPQExpBuffer(query, ", SYNCHRONOUS_COMMIT = %s", fmtId(subinfo->subsynccommit));
appendPQExpBufferStr(query, ");\n");
appendPQExpBuffer(labelq, "SUBSCRIPTION %s", fmtId(subinfo->dobj.name));

1
src/bin/pg_dump/pg_dump.h
View File

@ -616,6 +616,7 @@ typedef struct _SubscriptionInfo
char *rolname;
char *subconninfo;
char *subslotname;
char *subsynccommit;
char *subpublications;
} SubscriptionInfo;

5
src/bin/psql/describe.c
View File

@ -5199,7 +5199,8 @@ describeSubscriptions(const char *pattern, bool verbose)
PQExpBufferData buf;
PGresult *res;
printQueryOpt myopt = pset.popt;
static const bool translate_columns[] = {false, false, false, false, false};
static const bool translate_columns[] = {false, false, false, false,
false, false};
if (pset.sversion < 100000)
{
@ -5225,7 +5226,9 @@ describeSubscriptions(const char *pattern, bool verbose)
if (verbose)
{
appendPQExpBuffer(&buf,
", subsynccommit AS \"%s\"\n"
", subconninfo AS \"%s\"\n",
gettext_noop("Synchronous commit"),
gettext_noop("Conninfo"));
}

8
src/include/catalog/pg_subscription.h
View File

@ -43,7 +43,7 @@ CATALOG(pg_subscription,6100) BKI_SHARED_RELATION BKI_ROWTYPE_OID(6101) BKI_SCHE
#ifdef CATALOG_VARLEN /* variable-length fields start here */
text subconninfo; /* Connection string to the publisher */
NameData subslotname; /* Slot name on publisher */
text subsynccommit; /* Synchronous commit setting for worker */
text subpublications[1]; /* List of publications subscribed to */
#endif
} FormData_pg_subscription;
@ -54,14 +54,15 @@ typedef FormData_pg_subscription *Form_pg_subscription;
* compiler constants for pg_subscription
* ----------------
*/
#define Natts_pg_subscription 7
#define Natts_pg_subscription 8
#define Anum_pg_subscription_subdbid 1
#define Anum_pg_subscription_subname 2
#define Anum_pg_subscription_subowner 3
#define Anum_pg_subscription_subenabled 4
#define Anum_pg_subscription_subconninfo 5
#define Anum_pg_subscription_subslotname 6
#define Anum_pg_subscription_subpublications 7
#define Anum_pg_subscription_subsynccommit 7
#define Anum_pg_subscription_subpublications 8
typedef struct Subscription
@ -73,6 +74,7 @@ typedef struct Subscription
bool enabled; /* Indicates if the subscription is enabled */
char *conninfo; /* Connection string to the publisher */
char *slotname; /* Name of the replication slot */
char *synccommit; /* Synchronous commit setting for worker */
List *publications; /* List of publication names to subscribe to */
} Subscription;

30
src/test/regress/expected/subscription.out
View File

@ -46,10 +46,10 @@ CREATE SUBSCRIPTION testsub2 CONNECTION 'dbname=doesnotexist' PUBLICATION foo WI
ERROR: must be superuser to create subscriptions
SET SESSION AUTHORIZATION 'regress_subscription_user';
\dRs+
List of subscriptions
Name | Owner | Enabled | Publication | Conninfo
---------+---------------------------+---------+-------------+---------------------
testsub | regress_subscription_user | f | {testpub} | dbname=doesnotexist
List of subscriptions
Name | Owner | Enabled | Publication | Synchronous commit | Conninfo
---------+---------------------------+---------+-------------+--------------------+---------------------
testsub | regress_subscription_user | f | {testpub} | off | dbname=doesnotexist
(1 row)
ALTER SUBSCRIPTION testsub SET PUBLICATION testpub2, testpub3 NOREFRESH;
@ -59,10 +59,10 @@ ALTER SUBSCRIPTION testsub WITH (SLOT NAME = 'newname');
ALTER SUBSCRIPTION doesnotexist CONNECTION 'dbname=doesnotexist2';
ERROR: subscription "doesnotexist" does not exist
\dRs+
List of subscriptions
Name | Owner | Enabled | Publication | Conninfo
---------+---------------------------+---------+---------------------+----------------------
testsub | regress_subscription_user | f | {testpub2,testpub3} | dbname=doesnotexist2
List of subscriptions
Name | Owner | Enabled | Publication | Synchronous commit | Conninfo
---------+---------------------------+---------+---------------------+--------------------+----------------------
testsub | regress_subscription_user | f | {testpub2,testpub3} | off | dbname=doesnotexist2
(1 row)
BEGIN;
@ -89,11 +89,15 @@ ALTER SUBSCRIPTION testsub RENAME TO testsub_dummy;
ERROR: must be owner of subscription testsub
RESET ROLE;
ALTER SUBSCRIPTION testsub RENAME TO testsub_foo;
\dRs
List of subscriptions
Name | Owner | Enabled | Publication
-------------+---------------------------+---------+---------------------
testsub_foo | regress_subscription_user | f | {testpub2,testpub3}
ALTER SUBSCRIPTION testsub_foo WITH (SYNCHRONOUS_COMMIT = local);
ALTER SUBSCRIPTION testsub_foo WITH (SYNCHRONOUS_COMMIT = foobar);
ERROR: invalid value for parameter "synchronous_commit": "foobar"
HINT: Available values: local, remote_write, remote_apply, on, off.
\dRs+
List of subscriptions
Name | Owner | Enabled | Publication | Synchronous commit | Conninfo
-------------+---------------------------+---------+---------------------+--------------------+----------------------
testsub_foo | regress_subscription_user | f | {testpub2,testpub3} | local | dbname=doesnotexist2
(1 row)
-- rename back to keep the rest simple

4
src/test/regress/sql/subscription.sql
View File

@ -66,8 +66,10 @@ ALTER SUBSCRIPTION testsub RENAME TO testsub_dummy;
RESET ROLE;
ALTER SUBSCRIPTION testsub RENAME TO testsub_foo;
ALTER SUBSCRIPTION testsub_foo WITH (SYNCHRONOUS_COMMIT = local);
ALTER SUBSCRIPTION testsub_foo WITH (SYNCHRONOUS_COMMIT = foobar);
\dRs
\dRs+
-- rename back to keep the rest simple
ALTER SUBSCRIPTION testsub_foo RENAME TO testsub;