PROGRAM = pg_standby

OBJS= pg_standby.o

PG_CPPFLAGS = -I$(libpq_srcdir)

PG_LIBS =$(libpq_pgport)

DOCS = README.pg_standby

PGXS :=$(shell pg_config --pgxs)

else

subdir = contrib/pg_standby

top_builddir = ../..

include$(top_builddir)/src/Makefile.global

include$(top_srcdir)/contrib/contrib-global.mk

pg_standby README2006/12/08 Simon Riggs

o What is pg_standby?

pg_standby is a production-ready program that can be used to

create a Warm Standby server. Other configuration is required

as well, all of which is described in the main server manual.

The program is designed to be a wait-for restore_command,

required to turn a normal archive recovery into a Warm Standby.

Within the restore_command of the recovery.conf you could

configure pg_standby in the following way:

restore_command = 'pg_standby archiveDir %f %p'

which would be sufficient to define that files will be restored

from archiveDir.

o features of pg_standby

- pg_standby is written in C. So it is very portable

and easy to install.

- supports copy or link from a directory (only)

- source easy to modify, with specifically designated

sections to modify for your own needs, allowing

interfaces to be written for additional Backup Archive Restore

(BAR) systems

- portable: tested on Linux and Windows

o How to install pg_standby

$make

$make install

o How to use pg_standby?

pg_standby should be used within the restore_command of the

recovery.conf file. See the main PostgreSQL manual for details.

The basic usage should be like this:

restore_command = 'pg_standby archiveDir %f %p'

with the pg_standby command usage as

pg_standby [OPTION]... [ARCHIVELOCATION] [NEXTWALFILE] [XLOGFILEPATH]

When used within the restore_command the %f and %p macros

will provide the actual file and path required for the restore/recovery.

o options

pg_standby has number of options.

-c

use copy/cp command to restore WAL files from archive

-d

debug/logging option.

-k numfiles

Cleanup files in the archive so that we maintain no more

than this many files in the archive.

You should be wary against setting this number too low,

since this may mean you cannot restart the standby. This

is because the last restartpoint marked in the WAL files

may be many files in the past and can vary considerably.

This should be set to a value exceeding the number of WAL

files that can be recovered in 2*checkpoint_timeout seconds,

according to the value in the warm standby postgresql.conf.

It is wholly unrelated to the setting of checkpoint_segments

on either primary or standby.

If in doubt, use a large value or do not set a value at all.

-l

use ln command to restore WAL files from archive

WAL files will remain in archive

Link is more efficient, but the default is copy to

allow you to maintain the WAL archive for recovery

purposes as well as high-availability.

This option uses the Windows Vista command mklink

to provide a file-to-file symbolic link. -l will

not work on versions of Windows prior to Vista.

Use the -c option instead.

see http://en.wikipedia.org/wiki/NTFS_symbolic_link

-r maxretries

the maximum number of times to retry the restore command if it

fails. 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 database server. This will be

interpreted as and end of recovery and the Standby will come

up fully as a result.

Default=3

-s sleeptime

the number of seconds to sleep between testing to see

if the file to be restored is available in the archive yet.

The default setting is not necessarily recommended,

consult the main database server manual for discussion.

Default=5

-t triggerfile

the presence of the triggerfile will cause recovery to end

whether or not the next file is available

It is recommended that you use a structured filename to

avoid confusion as to which server is being triggered

when multiple servers exist on same system.

e.g. /tmp/pgsql.trigger.5432

-w maxwaittime

the maximum number of seconds to wait for the next file,

after which recovery will end and the Standby will come up.

The default setting is not necessarily recommended,

consult the main database server manual for discussion.

Default=0

Note: --help is not supported since pg_standby is not intended

for interactive use, except during dev/test

o examples

Linux

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

restore_command = 'pg_standby -l -d -k 255 -r 2 -s 2 -w 0 -t /tmp/pgsql.trigger.5442 $PWD/../archive %f %p 2>> standby.log'

which will

- use a ln command to restore WAL files from archive

- produce logfile output in standby.log

- keep the last 255 full WAL files, plus the current one

- sleep for 2 seconds between checks for next WAL file is full

- never timeout if file not found

- stop waiting when a trigger file called /tmp.pgsql.trigger.5442 appears

Windows

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

Note that backslashes need to be doubled in the archive_command, but

*not* in the restore_command, in 8.2, 8.1, 8.0 on Windows.

restore_command = 'pg_standby -c -d -s 5 -w 0 -t C:\pgsql.trigger.5442

..\archive %f %p 2>> standby.log'

which will

- use a copy command to restore WAL files from archive

- produce logfile output in standby.log

- sleep for 5 seconds between checks for next WAL file is full

- never timeout if file not found

- stop waiting when a trigger file called C:\pgsql.trigger.5442 appears

o reported test success

SUSE Linux 10.2

Windows XP Pro