On Tuesday 25 March 2008, sathiya psql wrote: > Dear Friends, > I have a table with 32 lakh record in it. Table size is nearly 700 MB, > and my machine had a 1 GB + 256 MB RAM, i had created the table space in > RAM, and then created this table in this RAM. > > So now everything is in RAM, if i do a count(*) on this table it > returns 327600 in 3 seconds, why it is taking 3 seconds ????? because am > sure that no Disk I/O is happening. ( using vmstat i had confirmed, no disk > I/O is happening, swap is also not used ) > > Any Idea on this ??? > > I searched a lot in newsgroups ... can't find relevant things.... ( because > everywhere they are speaking about disk access speed, here i don't want to > worry about disk access ) > > If required i will give more information on this. I can't really say anything about your RAM issue, but count(*) is always a bad idea if it can be avoided. Assuming you have a primary key on the table, do a count(pk). In my experience that alone cuts down up to 30% of execution time. Uwe -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
