On Tue, 4 Mar 2003, Chris Sutton wrote: > Hello, > > I need some insight on the best way to use a RAM drive in a Postgresql > installation. Here is our situation and current setup: > > Postgresql 7.2.1
First suggestion: upgrade to 7.2.4 to address several bugs. > The concern of course is if something happends to the RAM drive we are > S.O.L. and have to go to the last backup (pg_dump happens each night). If you are concerned, I would definitely backup more often. Increased performance of the disk system will speed up dumps. > The other concern is if the disk size of the database grows past or near > 8gb, we would either have to get a bigger RAM drive or somehow split > things betten SCSI and RAM drive. There has been a lot of talk over the last few years about introducing user-defined storage locations for objects under Postgres. I'm not sure that this will get into 7.4. If it did, I would recommend storing hot tables/indexes (frequently accessed) and all temporary backing files (used for large sorts, joins, etc). The problem is, however, making sure the planner knows that the cost of retrieving a page is different on a solid state disk when compared to a RAID 5 on a PC. You *could* use symlinks, but postgres wont know anything about them: operations on relations/objects such as add, drop, rename, etc will simply unlink the symlink and create a new file on the disk system. > Should we just put pgsql/data/pg_xlog on the RAM drive? You need to look at the nature of your database. If it is static, pg_xlog isn't seeing much action. If there is a small amount of modification to data but you can get it all with pg_dump on a frequent basis -- sure, putting pg_xlog on a RAM disk will speed it up. If your database is getting updated often and you cannot afford to lose data during a powerfailure (RAM disk goes down too), then don't put pg_xlog on it. In fact, put nothing important on it. You can get a similar performance increase by turning off fsync() in postgresql.conf -- but, you lose the guarantee of the persistence of your data. Gavin ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]