The ext3fs allows to selet type of journalling to be used with
filesystem. Journalling pretty much "mirrors" the work of WAL
logging by PostgreSQL... I wonder which type of journalling
is best for PgSQL in terms of performance.
Choices include:
journal
All data is committed into the journal prior to being
written into the main file system.
ordered
This is the default mode. All data is forced directly
out to the main file system prior to its metadata being
committed to the journal.
writeback
Data ordering is not preserved - data may be written into
the main file system after its metadata has been commit-
ted to the journal. This is rumoured to be the highest-
throughput option. It guarantees internal file system
integrity, however it can allow old data to appear in
files after a crash and journal recovery.
Am I right to assume that "writeback" is both fastest and at the same
time as safe to use as ordered? Maybe any of you did some benchmarks?
Regards,
Dawid