PG_STANDBY man page on RedHat

Man page or keyword search:  
man Server   29550 pages
apropos Keyword Search (all sections)
Output format
RedHat logo
[printable version]

PG_STANDBY(1)		PostgreSQL 9.2.5 Documentation		 PG_STANDBY(1)

NAME
       pg_standby - supports the creation of a PostgreSQL warm standby server

SYNOPSIS
       pg_standby [option...] archivelocation nextwalfile xlogfilepath
		  [restartwalfile]

DESCRIPTION
       pg_standby supports creation of a “warm standby” database server. It is
       designed to be a production-ready program, as well as a customizable
       template should you require specific modifications.

       pg_standby is designed to be a waiting restore_command, which is needed
       to turn a standard archive recovery into a warm standby operation.
       Other configuration is required as well, all of which is described in
       the main server manual (see Section 25.2, “Log-Shipping Standby
       Servers”, in the documentation).

       To configure a standby server to use pg_standby, put this into its
       recovery.conf configuration file:

	   restore_command = 'pg_standby archiveDir %f %p %r'

       where archiveDir is the directory from which WAL segment files should
       be restored.

       If restartwalfile is specified, normally by using the %r macro, then
       all WAL files logically preceding this file will be removed from
       archivelocation. This minimizes the number of files that need to be
       retained, while preserving crash-restart capability. Use of this
       parameter is appropriate if the archivelocation is a transient staging
       area for this particular standby server, but not when the
       archivelocation is intended as a long-term WAL archive area.

       pg_standby assumes that archivelocation is a directory readable by the
       server-owning user. If restartwalfile (or -k) is specified, the
       archivelocation directory must be writable too.

       There are two ways to fail over to a “warm standby” database server
       when the master server fails:

       Smart Failover
	   In smart failover, the server is brought up after applying all WAL
	   files available in the archive. This results in zero data loss,
	   even if the standby server has fallen behind, but if there is a lot
	   of unapplied WAL it can be a long time before the standby server
	   becomes ready. To trigger a smart failover, create a trigger file
	   containing the word smart, or just create it and leave it empty.

       Fast Failover
	   In fast failover, the server is brought up immediately. Any WAL
	   files in the archive that have not yet been applied will be
	   ignored, and all transactions in those files are lost. To trigger a
	   fast failover, create a trigger file and write the word fast into
	   it.	pg_standby can also be configured to execute a fast failover
	   automatically if no new WAL file appears within a defined interval.

OPTIONS
       pg_standby accepts the following command-line arguments:

       -c
	   Use cp or copy command to restore WAL files from archive. This is
	   the only supported behavior so this option is useless.

       -d
	   Print lots of debug logging output on stderr.

       -k
	   Remove files from archivelocation so that no more than this many
	   WAL files before the current one are kept in the archive. Zero (the
	   default) means not to remove any files from archivelocation. This
	   parameter will be silently ignored if restartwalfile is specified,
	   since that specification method is more accurate in determining the
	   correct archive cut-off point. Use of this parameter is deprecated
	   as of PostgreSQL 8.3; it is safer and more efficient to specify a
	   restartwalfile parameter. A too small setting could result in
	   removal of files that are still needed for a restart of the standby
	   server, while a too large setting wastes archive space.

       -r maxretries
	   Set the maximum number of times to retry the copy command if it
	   fails (default 3). After each failure, we wait for sleeptime *
	   num_retries so that the wait time increases progressively. So by
	   default, we will wait 5 secs, 10 secs, then 15 secs before
	   reporting the failure back to the standby server. This will be
	   interpreted as end of recovery and the standby will come up fully
	   as a result.

       -s sleeptime
	   Set the number of seconds (up to 60, default 5) to sleep between
	   tests to see if the WAL file to be restored is available in the
	   archive yet. The default setting is not necessarily recommended;
	   consult Section 25.2, “Log-Shipping Standby Servers”, in the
	   documentation for discussion.

       -t triggerfile
	   Specify a trigger file whose presence should cause failover. It is
	   recommended that you use a structured file name to avoid confusion
	   as to which server is being triggered when multiple servers exist
	   on the same system; for example /tmp/pgsql.trigger.5432.

       -V, --version
	   Print the pg_standby version and exit.

       -w maxwaittime
	   Set the maximum number of seconds to wait for the next WAL file,
	   after which a fast failover will be performed. A setting of zero
	   (the default) means wait forever. The default setting is not
	   necessarily recommended; consult Section 25.2, “Log-Shipping
	   Standby Servers”, in the documentation for discussion.

       -?, --help
	   Show help about pg_standby command line arguments, and exit.

NOTES
       pg_standby is designed to work with PostgreSQL 8.2 and later.

       PostgreSQL 8.3 provides the %r macro, which is designed to let
       pg_standby know the last file it needs to keep. With PostgreSQL 8.2,
       the -k option must be used if archive cleanup is required. This option
       remains available in 8.3, but its use is deprecated.

       PostgreSQL 8.4 provides the recovery_end_command option. Without this
       option a leftover trigger file can be hazardous.

       pg_standby is written in C and has an easy-to-modify source code, with
       specifically designated sections to modify for your own needs

EXAMPLES
       On Linux or Unix systems, you might use:

	   archive_command = 'cp %p .../archive/%f'

	   restore_command = 'pg_standby -d -s 2 -t /tmp/pgsql.trigger.5442 .../archive %f %p %r 2>>standby.log'

	   recovery_end_command = 'rm -f /tmp/pgsql.trigger.5442'

       where the archive directory is physically located on the standby
       server, so that the archive_command is accessing it across NFS, but the
       files are local to the standby (enabling use of ln). This will:

       ·   produce debugging output in standby.log

       ·   sleep for 2 seconds between checks for next WAL file availability

       ·   stop waiting only when a trigger file called
	   /tmp/pgsql.trigger.5442 appears, and perform failover according to
	   its content

       ·   remove the trigger file when recovery ends

       ·   remove no-longer-needed files from the archive directory

       On Windows, you might use:

	   archive_command = 'copy %p ...\\archive\\%f'

	   restore_command = 'pg_standby -d -s 5 -t C:\pgsql.trigger.5442 ...\archive %f %p %r 2>>standby.log'

	   recovery_end_command = 'del C:\pgsql.trigger.5442'

       Note that backslashes need to be doubled in the archive_command, but
       not in the restore_command or recovery_end_command. This will:

       ·   use the copy command to restore WAL files from archive

       ·   produce debugging output in standby.log

       ·   sleep for 5 seconds between checks for next WAL file availability

       ·   stop waiting only when a trigger file called C:\pgsql.trigger.5442
	   appears, and perform failover according to its content

       ·   remove the trigger file when recovery ends

       ·   remove no-longer-needed files from the archive directory

       The copy command on Windows sets the final file size before the file is
       completely copied, which would ordinarily confuse pg_standby. Therefore
       pg_standby waits sleeptime seconds once it sees the proper file size.
       GNUWin32's cp sets the file size only after the file copy is complete.

       Since the Windows example uses copy at both ends, either or both
       servers might be accessing the archive directory across the network.

AUTHOR
       Simon Riggs <simon@2ndquadrant.com>

SEE ALSO
       pg_archivecleanup(1)

PostgreSQL 9.2.5		  2013-10-08			 PG_STANDBY(1)
[top]

List of man pages available for RedHat

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net