Putting tables or indexes in SSD or RAM: avoiding double caching? - Mailing list pgsql-performance

From Shaul Dar
Subject Putting tables or indexes in SSD or RAM: avoiding double caching?
Date
Msg-id 234efe30905250651i67b86882q3d9eaa91d1432c01@mail.gmail.com
Whole thread Raw
List pgsql-performance
Hi,

I have sen many posts on using SSDs, and iodrive in particular, to accelerate the performance of Postgresql (or other DBMS) -- e.g. this discussion. I have also seen the suggestion to use RAM for the same purpose by creating a tablespace on a RAM mount point. Granted these make most sense when the whole database cannot fit into main memory, or if we want to avoid cold DB response times (i.e waiting for the DB to "warm up" as stuff gets cached in memory).

My question is this: if we use either SSD or RAM tablespaces, I would imagine postgresql will be oblevient to this and would still cache the tablespace elemenst that are on SSD or RAM into memory - right? Is there a way to avoid that, i.e. to tell postgress NOT to cache tablespaces, or some other granularity of the DB?

Thanks,

-- Shaul

Dr. Shaul Dar
Email: info@shauldar.com
Web: www.shauldar.com

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