On Wed, Feb 19, 2020 at 05:42:41AM +0100, Nicolas PARIS wrote: > Hi > > I have both hdd and ssd disk on the postgres server. The cluster is > right now created on the hdd only. I am considering using a tablespace > to put some highly used postgres object on the ssd disk. Of course the > ssd is small compared to the hdd, and I need to choose carefully what > objects are stored on that side. > > I am wondering what kind of object (indexes, data) would benefit from > ssd. The database primary/foreign keys are highly used and there is > almost no sequencial scan. However the server has a large amount of ram > memory and I suspect all of those indexes are already cached in ram. > > I have read that tablespaces introduce overhead of maintenance and > introduce complication for replication. But on the other hand I have > this ssd disk ready for something. To start with, you can: ALTER SYSTEM SET temp_tablespaces='ssd'; That will improve speed of sorts which spill to disk (if any). +1 to using LVM for purposes of instrumentation. You can also: ALTER TABLESPACE ssd SET (random_page_cost=1.0); It'd be difficult to suggest anything further without knowing about your workload or performance goals or issues. -- Justin
