Does PostgreSQL support transparent compressing of tables (fragments)?
I'm going to store large amount of data (logs) in fragmented PostgreSQL tables (table per day). I would like to compress some of them to save some space on my discs, but I don't want to lose the ability to query them in the usual manner.
Does PostgreSQL support such a transparent compression and where can I read about it in more detail? I think there should be some well-known magic name for such a feature.
Answer
Yes, PostgreSQL will do this automatically for you when they go above a certain size. Compression is applied at each individual data value though - not at the full table level. Meaning that if you have a billion rows that are very narrow, they won't get compressed. Or if you have very many columns each with only a small value in it, they won't get compressed. Details about this scheme in the manual.
If you need it on the full table level, a solution is to create a TABLESPACE for those tables that you want compressed, and point it to a compressed filesystem. As long as the filesystem still obeys fsync() and standard POSIX semantics, this should be perfectly safe. Details about this in the manual.