之前在研究pgpoll时，发现trigger_file参数指定的文件存在后，会自动将standby节点提升为可写节点。不需要手动执行pg_ctl promote，但是这个时间一般有延迟，因为进程会定期检查复制过程。
今天发现primary_conninfo信息改变，复制过程不会变化，需要重启standby节点。
............................................................................................................................
-bash-4.1$ cat recovery.conf.sample |more# ------------------------------- # PostgreSQL recovery config file # ------------------------------- # # Edit this file to provide the parameters that PostgreSQL needs to # perform an archive recovery of a database, or to act as a replication # standby. # # If "recovery.conf" is present in the PostgreSQL data directory, it is # read on postmaster startup. After successful recovery, it is renamed # to "recovery.done" to ensure that we do not accidentally re-enter # archive recovery or standby mode. # # This file consists of lines of the form: # # name = value # # Comments are introduced with ‘#‘. # # The complete list of option names and allowed values can be found # in the PostgreSQL documentation. # #--------------------------------------------------------------------------- # ARCHIVE RECOVERY PARAMETERS #--------------------------------------------------------------------------- # # restore_command # # specifies the shell command that is executed to copy log files # back from archival storage. The command string may contain %f, # which is replaced by the name of the desired log file, and %p, # which is replaced by the absolute path to copy the log file to. # # This parameter is *required* for an archive recovery, but optional # for streaming replication. # # It is important that the command return nonzero exit status on failure. # The command *will* be asked for log files that are not present in the # archive; it must return nonzero when so asked. # # NOTE that the basename of %p will be different from %f; do not # expect them to be interchangeable.
#restore_command = ‘‘ # e.g. ‘cp /mnt/server/archivedir/%f %p‘
#
#
# archive_cleanup_command
#
# specifies an optional shell command to execute at every restartpoint.
# This can be useful for cleaning up the archive of a standby server.
#
#archive_cleanup_command = ‘‘
#
# recovery_end_command
#
# specifies an optional shell command to execute at completion of recovery.
# This can be useful for cleaning up after the restore_command.
#
#recovery_end_command = ‘‘
#
#---------------------------------------------------------------------------
# RECOVERY TARGET PARAMETERS
#---------------------------------------------------------------------------
#
# By default, recovery will rollforward to the end of the WAL log.
# If you want to stop rollforward at a specific point, you
# must set a recovery target.
#
# You may set a recovery target either by transactionId, by name,
# or by timestamp. Recovery may either include or exclude the
# transaction(s) with the recovery target value (ie, stop either
# just after or just before the given target, respectively).
#
#
#recovery_target_name = ‘‘ # e.g. ‘daily backup 2011-01-26‘
#
#recovery_target_time = ‘‘ # e.g. ‘2004-07-14 22:39:00 EST‘
#
#recovery_target_xid = ‘‘
#
#recovery_target_inclusive = true
#
#
# Alternatively, you can request stopping as soon as a consistent state
# is reached, by uncommenting this option.
#recovery_target = ‘immediate‘
#
#
# If you want to recover into a timeline other than the "main line" shown in
# pg_control, specify the timeline number here, or write ‘latest‘ to get
# the latest branch for which there‘s a history file.
#
#recovery_target_timeline = ‘latest‘
#
#
# If recovery_target_action = ‘pause‘, recovery will pause when the
# recovery target is reached. The pause state will continue until
# pg_xlog_replay_resume() is called. This setting has no effect if
# no recovery target is set. If hot_standby is not enabled then the
# server will shutdown instead, though you may request this in
# any case by specifying ‘shutdown‘.
#
#recovery_target_action = ‘pause‘
#
#---------------------------------------------------------------------------
# STANDBY SERVER PARAMETERS
#---------------------------------------------------------------------------
#
# standby_mode
#
# When standby_mode is enabled, the PostgreSQL server will work as a
# standby. It will continuously wait for the additional XLOG records, using
# restore_command and/or primary_conninfo.
#
#standby_mode = off
#
# primary_conninfo
#
# If set, the PostgreSQL server will try to connect to the primary using this
# connection string and receive XLOG records continuously.
#
#primary_conninfo = ‘‘ # e.g. ‘host=localhost port=5432‘
#
# If set, the PostgreSQL server will use the specified replication slot when
# connecting to the primary via streaming replication to control resource
# removal on the upstream node. This setting has no effect if primary_conninfo
# is not set.
#
#primary_slot_name = ‘‘
#
# By default, a standby server keeps restoring XLOG records from the
# primary indefinitely. If you want to stop the standby mode, finish recovery
# and open the system in read/write mode, specify a path to a trigger file.
# The server will poll the trigger file path periodically and start as a
# primary server when it‘s found.
#
#trigger_file = ‘‘
#
# By default, a standby server restores XLOG records from the primary as
# soon as possible. If you want to explicitly delay the replay of committed
# transactions from the master, specify a minimum apply delay. For example,
# if you set this parameter to 5min, the standby will replay each transaction
# commit only when the system time on the standby is at least five minutes
# past the commit time reported by the master.
#
#recovery_min_apply_delay = 0
#
#---------------------------------------------------------------------------
# HOT STANDBY PARAMETERS
#---------------------------------------------------------------------------
#
# Hot Standby related parameters are listed in postgresql.conf
#
#---------------------------------------------------------------------------