On Wed, Oct 15, 2014 at 10:10 AM, Josh Berkus <j...@agliodbs.com> wrote:
> On 10/14/2014 10:08 AM, Dave Johansen wrote: > > I'm running Postgres 8.4 on RHEL 6 64-bit and I had a question about how > > work_mem and partitions interact. > > > > https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server#work_mem > > The above wiki states that "if a query involves doing merge sorts of 8 > > tables, that requires 8 times work_mem." If I have a table that is > > partitioned does each partition count as a "table" and get its on > work_mem? > > In theory, this could happen. In practice, based on tests I did at Sun > with DBT3 and 8.3, no backend ever used more than 3X work_mem. This is > partly because the level of parallelism in postgres is extremely > limited, so we can't actually sort 8 partitions at the same time. > Thanks for the feedback. That's very helpful. > BTW, 8.4 is EOL. Maybe time to upgrade? > RHEL 6 isn't EOLed and we're working on moving to RHEL 7 but it's a slow process that will probably take quite a bit of time, if it ever happens.
