On Thu, Jan 25, 2018 at 8:54 PM, Tsunakawa, Takayuki <tsunakawa.ta...@jp.fujitsu.com> wrote: > Yes, that's pg_test_fsync output. Isn't pg_test_fsync the tool to determine > the value for wal_sync_method? Is this manual misleading?
Hmm. I hadn't thought about it as misleading, but now that you mention it, I'd say that it probably is. I suspect that there should be a disclaimer saying that the fastest WAL sync method in terms of ops/second is not necessarily the one that will deliver the best database performance, and mention the issues around open_sync and open_datasync specifically. But let's see what your testing shows; I'm talking based on now-fairly-old experience with this and a passing familiarity with the relevant source code. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
