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Commitaceedd8

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Make vacuum_defer_cleanup_age be PGC_SIGHUP level, since it's not sensible
to have different values in different processes of the primary server.Also put it into the "Streaming Replication" GUC category; it doesn't belongin "Standby Servers" because you use it on the master not the standby.In passing also correct guc.c's idea of wal_keep_segments' category.
1 parente76c1a0 commitaceedd8

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4 files changed

+41
-31
lines changed

4 files changed

+41
-31
lines changed

‎doc/src/sgml/config.sgml

Lines changed: 26 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.289 2010/07/0320:43:57 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.290 2010/07/0321:23:58 tgl Exp $ -->
22

33
<chapter Id="runtime-config">
44
<title>Server Configuration</title>
@@ -1914,6 +1914,31 @@ SET ENABLE_SEQSCAN TO OFF;
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-vacuum-defer-cleanup-age" xreflabel="vacuum_defer_cleanup_age">
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<term><varname>vacuum_defer_cleanup_age</varname> (<type>integer</type>)</term>
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<indexterm>
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<primary><varname>vacuum_defer_cleanup_age</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the number of transactions by which <command>VACUUM</> and
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<acronym>HOT</> updates will defer cleanup of dead row versions. The
1927+
default is zero transactions, meaning that dead row versions can be
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removed as soon as possible, that is, as soon as they are no longer
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visible to any open transaction. You may wish to set this to a
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non-zero value on a primary server that is supporting hot standby
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servers, as described in <xref linkend="hot-standby">. This allows
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more time for queries on the standby to complete without incurring
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conflicts due to early cleanup of rows. However, since the value
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is measured in terms of number of write transactions occurring on the
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primary server, it is difficult to predict just how much additional
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grace time will be made available to standby queries.
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This parameter can only be set in the <filename>postgresql.conf</>
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file or on the server command line.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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@@ -2004,29 +2029,6 @@ SET ENABLE_SEQSCAN TO OFF;
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</listitem>
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</varlistentry>
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2007-
<varlistentry id="guc-vacuum-defer-cleanup-age" xreflabel="vacuum_defer_cleanup_age">
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<term><varname>vacuum_defer_cleanup_age</varname> (<type>integer</type>)</term>
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<indexterm>
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<primary><varname>vacuum_defer_cleanup_age</> configuration parameter</primary>
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</indexterm>
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<listitem>
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<para>
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Specifies the number of transactions by which <command>VACUUM</> and
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<acronym>HOT</> updates will defer cleanup of dead row versions. The
2016-
default is 0 transactions, meaning that dead row versions will be
2017-
removed as soon as possible. You may wish to set this to a non-zero
2018-
value when planning or maintaining a Hot Standby connection, as
2019-
described in <xref linkend="hot-standby">. The recommended value is
2020-
<literal>0</> unless you have clear reason to increase it. The purpose
2021-
of the parameter is to allow the user to specify an approximate time
2022-
delay before cleanup occurs. However, it should be noted that there is
2023-
no direct link with any specific time delay and so the results will be
2024-
application and installation specific, as well as variable over time,
2025-
depending upon the transaction rate (of writes only).
2026-
</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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</sect1>

‎src/backend/storage/ipc/procarray.c

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.70 2010/05/14 07:11:49 sriggs Exp $
40+
* $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.71 2010/07/03 21:23:58 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -1117,7 +1117,15 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum)
11171117
LWLockRelease(ProcArrayLock);
11181118

11191119
/*
1120-
* Compute the cutoff XID, being careful not to generate a "permanent" XID
1120+
* Compute the cutoff XID, being careful not to generate a "permanent" XID.
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*
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* vacuum_defer_cleanup_age provides some additional "slop" for the
1123+
* benefit of hot standby queries on slave servers. This is quick and
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* dirty, and perhaps not all that useful unless the master has a
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* predictable transaction rate, but it's what we've got. Note that
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* we are assuming vacuum_defer_cleanup_age isn't large enough to cause
1127+
* wraparound --- so guc.c should limit it to no more than the xidStopLimit
1128+
* threshold in varsup.c.
11211129
*/
11221130
result-=vacuum_defer_cleanup_age;
11231131
if (!TransactionIdIsNormal(result))

‎src/backend/utils/misc/guc.c

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Written by Peter Eisentraut <peter_e@gmx.net>.
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*
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* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.558 2010/07/0320:43:58 tgl Exp $
13+
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.559 2010/07/0321:23:58 tgl Exp $
1414
*
1515
*--------------------------------------------------------------------
1616
*/
@@ -1631,8 +1631,8 @@ static struct config_int ConfigureNamesInt[] =
16311631
},
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{
1634-
{"vacuum_defer_cleanup_age",PGC_USERSET,WAL_STANDBY_SERVERS,
1635-
gettext_noop("Age by which VACUUM and HOT cleanup should be deferred, if any."),
1634+
{"vacuum_defer_cleanup_age",PGC_SIGHUP,WAL_REPLICATION,
1635+
gettext_noop("Number of transactions by which VACUUM and HOT cleanup should be deferred, if any."),
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NULL
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},
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&vacuum_defer_cleanup_age,
@@ -1675,7 +1675,7 @@ static struct config_int ConfigureNamesInt[] =
16751675
},
16761676

16771677
{
1678-
{"wal_keep_segments",PGC_SIGHUP,WAL_CHECKPOINTS,
1678+
{"wal_keep_segments",PGC_SIGHUP,WAL_REPLICATION,
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gettext_noop("Sets the number of WAL files held for standby servers."),
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NULL
16811681
},

‎src/backend/utils/misc/postgresql.conf.sample

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -188,6 +188,7 @@
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#max_wal_senders = 0# max number of walsender processes
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#wal_sender_delay = 200ms# walsender cycle time, 1-10000 milliseconds
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#wal_keep_segments = 0# in logfile segments, 16MB each; 0 disables
191+
#vacuum_defer_cleanup_age = 0# number of xacts by which cleanup is delayed
191192

192193
# - Standby Servers -
193194

@@ -198,7 +199,6 @@
198199
#max_standby_streaming_delay = 30s# max delay before canceling queries
199200
# when reading streaming WAL;
200201
# -1 allows indefinite delay
201-
#vacuum_defer_cleanup_age = 0# number of transactions by which cleanup is deferred
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#------------------------------------------------------------------------------

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