Gbase 8C recovery control function

The recovery information function provides information about the current standby state . These functions may be executed during recovery or during normal operation .

pg_is_in_recovery()

describe ： If the recovery is still in progress, return true.

return type ：bool

pg_last_xlog_receive_location()

describe ： Get the location of the last received transaction log and synchronize it to disk through stream replication . When stream replication is in progress , The transaction log will continue to increment . If the recovery is complete , The last acquired WAL Records will be statically maintained and synchronized to disk during recovery . If stream replication is not available , Or it hasn't started yet , This function returns NULL.

return type ：text

pg_last_xlog_replay_location()

describe ： Get the replay location of the last transaction log during recovery . If the recovery is still in progress , The transaction log will continue to increment . If the recovery has been completed , Will remain last received during recovery WAL Recorded values . If the server starts normally without recovery , Then this function returns NULL.

return type ：text

pg_last_xact_replay_timestamp()

describe ： Get the timestamp of the replay of the last transaction upon recovery . This is for generating transaction commit or termination on the master node WAL Recorded time . If there is no transaction replay during recovery , Then this function returns NULL. If the recovery is still in progress , Then the transaction log will continue to increase . If the recovery is complete , Will remain last received during recovery WAL Recorded values . If the server starts normally without recovery , Then this function returns NULL.

return type ：timestamp with time zone

The recovery control function controls the recovery process . These functions may only be executed during recovery .

pg_is_xlog_replay_paused()

describe ： If you resume the pause, return true.

return type ：bool

pg_xlog_replay_pause()

describe ： Pause and resume immediately .

return type ：void

pg_xlog_replay_resume()

describe ： If the recovery is suspended , Then reboot .

return type ：void

When resuming the pause , No database changes have occurred . If it is in hot standby , All new queries will see a consistent database snapshot , And there will be no further query conflicts , Until recovery continues .

If you cannot use stream replication , Then the suspended state will continue indefinitely . When stream replication is in progress , Will receive continuously WAL Record , It will eventually fill up the available disk space , This progress depends on the duration of the pause ,WAL Generated speed and available disk space .