14.5. Non-Durable Settings

Durability is a database feature that guarantees the recording of committed transactions even if the server crashes or loses power. However, durability adds significant database overhead, so if your site does not require such a guarantee, Postgres-XC can be configured to run much faster. The following are configuration changes you can make to improve performance in such cases. Except as noted below, durability is still guaranteed in case of a crash of the database software; only abrupt operating system stoppage creates a risk of data loss or corruption when these settings are used.

• Place the database cluster's data directory in a memory-backed file system (i.e. RAM disk). This eliminates all database disk I/O, but limits data storage to the amount of available memory (and perhaps swap).

• Turn off fsync; there is no need to flush data to disk.

• Turn off full_page_writes; there is no need to guard against partial page writes.

• Increase checkpoint_segments and checkpoint_timeout ; this reduces the frequency of checkpoints, but increases the storage requirements of /pg_xlog.

• Turn off synchronous_commit; there might be no need to write the WAL to disk on every commit. This setting does risk transaction loss (though not data corruption) in case of a crash of the database alone.