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Remove promote_trigger_file. 

Previously, an idle startup (recovery) process would wake up every 5
seconds to have a chance to poll for promote_trigger_file, even if that
GUC was not configured.  That promotion triggering mechanism was
effectively superseded by pg_ctl promote and pg_promote() a long time
ago.  There probably aren't many users left and it's very easy to change
to the modern mechanisms, so we agreed to remove the feature.

This is part of a campaign to reduce wakeups on idle systems.

Author: Simon Riggs <simon.riggs@enterprisedb.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Ian Lawrence Barwick <barwick@gmail.com>
Discussion: https://postgr.es/m/CANbhV-FsjnzVOQGBpQ589%3DnWuL1Ex0Ykn74Nh1hEjp2usZSR5g%40mail.gmail.com
This commit is contained in:
Thomas Munro 2022-11-29 11:28:08 +13:00
parent f0cd57f852
commit cd4329d939
7 changed files with 29 additions and 93 deletions
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13
doc/src/sgml/appendix-obsolete-recovery-config.sgml
View File

@ -34,14 +34,11 @@
</para>
<para>
The
<literal>trigger_file</literal>
<indexterm>
<primary>trigger_file</primary>
<see>promote_trigger_file</see>
</indexterm>
setting has been renamed to
<xref linkend="guc-promote-trigger-file"/>.
PostgreSQL 15 and below had a setting
<literal>promote_trigger_file</literal>, or
<literal>trigger_file</literal> before 12.
Use <command>pg_ctl promote</command> or call
<function>pg_promote()</function> to promote a standby instead.
</para>
<para>

18
doc/src/sgml/config.sgml
View File

@ -4610,24 +4610,6 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
</listitem>
</varlistentry>
<varlistentry id="guc-promote-trigger-file" xreflabel="promote_trigger_file">
<term><varname>promote_trigger_file</varname> (<type>string</type>)
<indexterm>
<primary><varname>promote_trigger_file</varname> configuration parameter</primary>
</indexterm>
</term>
<listitem>
<para>
Specifies a trigger file whose presence ends recovery in the
standby. Even if this value is not set, you can still promote
the standby using <command>pg_ctl promote</command> or calling
<function>pg_promote()</function>.
This parameter can only be set in the <filename>postgresql.conf</filename>
file or on the server command line.
</para>
</listitem>
</varlistentry>
<varlistentry id="guc-hot-standby" xreflabel="hot_standby">
<term><varname>hot_standby</varname> (<type>boolean</type>)
<indexterm>

22
doc/src/sgml/high-availability.sgml
View File

@ -653,11 +653,10 @@ protocol to make nodes agree on a serializable transactional order.
<para>
Standby mode is exited and the server switches to normal operation
when <command>pg_ctl promote</command> is run,
<function>pg_promote()</function> is called, or a trigger file is found
(<varname>promote_trigger_file</varname>). Before failover,
any WAL immediately available in the archive or in <filename>pg_wal</filename> will be
restored, but no attempt is made to connect to the primary.
when <command>pg_ctl promote</command> is run, or
<function>pg_promote()</function> is called. Before failover,
any WAL immediately available in the archive or in <filename>pg_wal</filename>
will be restored, but no attempt is made to connect to the primary.
</para>
</sect2>
@ -1483,15 +1482,10 @@ synchronous_standby_names = 'ANY 2 (s1, s2, s3)'
<para>
To trigger failover of a log-shipping standby server, run
<command>pg_ctl promote</command>, call <function>pg_promote()</function>,
or create a trigger file with the file name and path specified by the
<varname>promote_trigger_file</varname>. If you're planning to use
<command>pg_ctl promote</command> or to call
<function>pg_promote()</function> to fail over,
<varname>promote_trigger_file</varname> is not required. If you're
setting up the reporting servers that are only used to offload read-only
queries from the primary, not for high availability purposes, you don't
need to promote it.
<command>pg_ctl promote</command> or call <function>pg_promote()</function>.
If you're setting up reporting servers that are only used to offload
read-only queries from the primary, not for high availability purposes,
you don't need to promote.
</para>
</sect1>

57
src/backend/access/transam/xlogrecovery.c
View File

@ -95,7 +95,6 @@ int recovery_min_apply_delay = 0;
/* options formerly taken from recovery.conf for XLOG streaming */
char *PrimaryConnInfo = NULL;
char *PrimarySlotName = NULL;
char *PromoteTriggerFile = NULL;
bool wal_receiver_create_temp_slot = false;
/*
@ -318,8 +317,8 @@ typedef struct XLogRecoveryCtlData
/*
* recoveryWakeupLatch is used to wake up the startup process to continue
* WAL replay, if it is waiting for WAL to arrive or failover trigger file
* to appear.
* WAL replay, if it is waiting for WAL to arrive or promotion to be
* requested.
*
* Note that the startup process also uses another latch, its procLatch,
* to wait for recovery conflict. If we get rid of recoveryWakeupLatch for
@ -2906,10 +2905,7 @@ recoveryApplyDelay(XLogReaderState *record)
{
ResetLatch(&XLogRecoveryCtl->recoveryWakeupLatch);
/*
* This might change recovery_min_apply_delay or the trigger file's
* location.
*/
/* This might change recovery_min_apply_delay. */
HandleStartupProcInterrupts();
if (CheckForStandbyTrigger())
@ -3155,8 +3151,8 @@ ReadRecord(XLogPrefetcher *xlogprefetcher, int emode,
* as for waiting for the requested WAL record to arrive in standby mode.
*
* 'emode' specifies the log level used for reporting "file not found" or
* "end of WAL" situations in archive recovery, or in standby mode when a
* trigger file is found. If set to WARNING or below, XLogPageRead() returns
* "end of WAL" situations in archive recovery, or in standby mode when
* promotion is triggered. If set to WARNING or below, XLogPageRead() returns
* XLREAD_FAIL in those situations, on higher log levels the ereport() won't
* return.
*
@ -3424,7 +3420,7 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
*
* 1. Read from either archive or pg_wal (XLOG_FROM_ARCHIVE), or just
* pg_wal (XLOG_FROM_PG_WAL)
* 2. Check trigger file
* 2. Check for promotion trigger request
* 3. Read from primary server via walreceiver (XLOG_FROM_STREAM)
* 4. Rescan timelines
* 5. Sleep wal_retrieve_retry_interval milliseconds, and loop back to 1.
@ -3481,10 +3477,10 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
case XLOG_FROM_PG_WAL:
/*
* Check to see if the trigger file exists. Note that we
* do this only after failure, so when you create the
* trigger file, we still finish replaying as much as we
* can from archive and pg_wal before failover.
* Check to see if promotion is requested. Note that we do
* this only after failure, so when you promote, we still
* finish replaying as much as we can from archive and
* pg_wal before failover.
*/
if (StandbyMode && CheckForStandbyTrigger())
{
@ -3840,14 +3836,13 @@ WaitForWALToBecomeAvailable(XLogRecPtr RecPtr, bool randAccess,
XLogPrefetcherComputeStats(xlogprefetcher);
/*
* Wait for more WAL to arrive. Time out after 5 seconds
* to react to a trigger file promptly and to check if the
* WAL receiver is still active.
* Wait for more WAL to arrive, when we will be woken
* immediately by the WAL receiver.
*/
(void) WaitLatch(&XLogRecoveryCtl->recoveryWakeupLatch,
WL_LATCH_SET | WL_TIMEOUT |
WL_EXIT_ON_PM_DEATH,
5000L, WAIT_EVENT_RECOVERY_WAL_STREAM);
WL_LATCH_SET | WL_EXIT_ON_PM_DEATH,
-1L,
WAIT_EVENT_RECOVERY_WAL_STREAM);
ResetLatch(&XLogRecoveryCtl->recoveryWakeupLatch);
break;
}
@ -4294,14 +4289,11 @@ SetPromoteIsTriggered(void)
}
/*
* Check to see whether the user-specified trigger file exists and whether a
* promote request has arrived. If either condition holds, return true.
* Check whether a promote request has arrived.
*/
static bool
CheckForStandbyTrigger(void)
{
struct stat stat_buf;
if (LocalPromoteIsTriggered)
return true;
@ -4314,23 +4306,6 @@ CheckForStandbyTrigger(void)
return true;
}
if (PromoteTriggerFile == NULL || strcmp(PromoteTriggerFile, "") == 0)
return false;
if (stat(PromoteTriggerFile, &stat_buf) == 0)
{
ereport(LOG,
(errmsg("promote trigger file found: %s", PromoteTriggerFile)));
unlink(PromoteTriggerFile);
SetPromoteIsTriggered();
return true;
}
else if (errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat promote trigger file \"%s\": %m",
PromoteTriggerFile)));
return false;
}

10
src/backend/utils/misc/guc_tables.c
View File

@ -3819,16 +3819,6 @@ struct config_string ConfigureNamesString[] =
check_recovery_target_lsn, assign_recovery_target_lsn, NULL
},
{
{"promote_trigger_file", PGC_SIGHUP, REPLICATION_STANDBY,
gettext_noop("Specifies a file name whose presence ends recovery in the standby."),
NULL
},
&PromoteTriggerFile,
"",
NULL, NULL, NULL
},
{
{"primary_conninfo", PGC_SIGHUP, REPLICATION_STANDBY,
gettext_noop("Sets the connection string to be used to connect to the sending server."),

1
src/backend/utils/misc/postgresql.conf.sample
View File

@ -331,7 +331,6 @@
#primary_conninfo = '' # connection string to sending server
#primary_slot_name = '' # replication slot on sending server
#promote_trigger_file = '' # file name whose presence ends recovery
#hot_standby = on # "off" disallows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries

1
src/include/access/xlogrecovery.h
View File

@ -65,7 +65,6 @@ extern PGDLLIMPORT TimestampTz recoveryTargetTime;
extern PGDLLIMPORT const char *recoveryTargetName;
extern PGDLLIMPORT XLogRecPtr recoveryTargetLSN;
extern PGDLLIMPORT RecoveryTargetType recoveryTarget;
extern PGDLLIMPORT char *PromoteTriggerFile;
extern PGDLLIMPORT bool wal_receiver_create_temp_slot;
extern PGDLLIMPORT RecoveryTargetTimeLineGoal recoveryTargetTimeLineGoal;
extern PGDLLIMPORT TimeLineID recoveryTargetTLIRequested;