Backup a hot standby database (streaming replication) whilst it is in recovery

Question

Synchronous Streaming Replicating is set up between a master and a hot standby database.

It seems like a good idea to perform daily backups on the standby database to avoid any performance issues on the master database.

The backup of the standby db was successfully restored using pg_basebackup. Archived WAL files were transferred locally and the restore_command was added in recovery.conf to point to them - the following errors were recorded in the log files whilst starting up the database:

cp: cannot stat ‘/archivedir/wal_arch/00000002.history’: No such file or directory 2016-05-12 17:33:52 BST LOG: starting archive recovery cp: cannot stat ‘/archivedir/wal_arch/0000000100000000000000E7’: No such file or directory 2016-05-12 17:33:52 BST LOG: redo starts at 0/E7000CA0 2016-05-12 17:33:52 BST LOG: consistent recovery state reached at 0/E7000D80 2016-05-12 17:33:52 BST LOG: invalid resource manager ID 100 at 0/E7000D80 2016-05-12 17:33:52 BST LOG: redo done at 0/E7000D48 cp: cannot stat ‘/archivedir/wal_arch/0000000100000000000000E7’: No such file or directory cp: cannot stat ‘/archivedir/wal_arch/00000002.history’: No such file or directory 2016-05-12 17:33:52 BST LOG: selected new timeline ID: 2 cp: cannot stat ‘/archivedir/wal_arch/00000001.history’: No such file or directory 2016-05-12 17:33:52 BST LOG: archive recovery complete 2016-05-12 17:33:52 BST LOG: MultiXact member wraparound protections are now enabled 2016-05-12 17:33:52 BST LOG: database system is ready to accept connections 2016-05-12 17:33:52 BST LOG: autovacuum launcher started

Is it a good idea to backup the standby database instead of the master?

Answer 1

Yes, it can be a good idea. In fact, allowing this was a major feature in the release of PostgreSQL 9.2.