Re: Disable WAL completely - Performance and Persistency research

On 11 July 2016 at 19:14, Netanel Katzburg <netanel10k(at)gmail(dot)com> wrote:

> Hi,
>
> You were right, the method you described worked well. Thanks you!
>
> But so far, could not get any noticeable improvement in Number of
> transactions / latency.
>
>
What are you comparing to?

To start with, compare with:

- an unpatched PostgreSQL, configured normally, with normal logged tables

- an unpatched PostgreSQL, using UNLOGGED tables

- an unpatched PostgreSQL, using UNLOGGED tables and synchronous_commit =
off (or fsync=off, but remember, that disables data integrity protections
for system catalogs and everything).

Make sure you're introducing a suitably write-concurrent workload that
might actually be waiting on WAL.

Personally I'd be surprised if you saw any significant difference over
using UNLOGGED tables. That's why we have them ;)

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services