Обсуждение: cache whole data in RAM
Hi, we are trying to speed up a database which has about 3 GB of data. The server has 8 GB RAM and we wonder how we can ensure that the whole DB is read into RAM. We hope that this will speed up some queries. regards David
David Teran wrote: > we are trying to speed up a database which has about 3 GB of data. The > server has 8 GB RAM and we wonder how we can ensure that the whole DB is > read into RAM. We hope that this will speed up some queries. Neither the DBa or postgresql has to do anything about it. Usually OS caches the data in it's buffer cache. That is certainly true for linux and freeBSD does that. Most of the unices certainly do. To my knowledge linux is most aggresive one at that..(Rather over aggressive..) Make sure that you size effective cache size correctly. It helps postgresql planner at times.. HTH Shridhar
On Tue, Feb 03, 2004 at 13:54:17 +0100, David Teran <david.teran@cluster9.com> wrote: > Hi, > > we are trying to speed up a database which has about 3 GB of data. The > server has 8 GB RAM and we wonder how we can ensure that the whole DB > is read into RAM. We hope that this will speed up some queries. The OS should do this on its own. What you don't want to do is set shared_buffers (in postgresql.conf) too high. From what I remember from past discussions it should be something between about 1000 and 10000. sort_mem is trickier since that memory is per sort and a single query can potentially generate multiple parallel sorts. You will have to make some guesses for this based on what you think the number of concurrent sorts will be when the system is stressed and not use too much memory. You might also find that after a point you don't get a lot of benefit from increasing sort_mem. You should set effective_cache_size pretty large. Probably you want to subtract the space used by shared_buffers and sort_mem (* times estimated parallel sorts) and what you think is reasonable overhead for other processes from the 8GB of memory. Since your DB's disk blocks will almost certainly all be in buffer cache, you are going to want to set random_page_cost to be pretty close to 1.
Put it on a RAM disk. chris On Tue, 2004-02-03 at 07:54, David Teran wrote: > Hi, > > we are trying to speed up a database which has about 3 GB of data. The > server has 8 GB RAM and we wonder how we can ensure that the whole DB > is read into RAM. We hope that this will speed up some queries. > > regards David > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faqs/FAQ.html >
David Teran wrote: > Hi, > > we are trying to speed up a database which has about 3 GB of data. The > server has 8 GB RAM and we wonder how we can ensure that the whole DB is > read into RAM. We hope that this will speed up some queries. > > regards David > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faqs/FAQ.html > Upon bootup, automatically run "SELECT * FROM xyz" on every table in your database.