Re: [PERFORM] Slow queries on 9.3.1 despite use of index

2014-04-29 Thread Michael van Rooyen
On 2014/04/28 07:52 PM, Jeff Janes wrote: On Mon, Apr 28, 2014 at 10:12 AM, Michael van Rooyen mailto:mich...@loot.co.za>> wrote: It looks like something is causing your IO to seize up briefly. It is common for the sync phase of the checkpoint to do that, but that would only explai

Re: [PERFORM] Slow queries on 9.3.1 despite use of index

2014-04-28 Thread Michael van Rooyen
On 2014/04/28 07:50 PM, Tom Lane wrote: Michael van Rooyen writes: I'm trying to get to the bottom of a performance issue on a server running PostgreSQL 9.3.1 on Centos 5. Hm ... it seems pretty suspicious that all of these examples take just about exactly 1 second longer than you

[PERFORM] Slow queries on 9.3.1 despite use of index

2014-04-28 Thread Michael van Rooyen
I'm trying to get to the bottom of a performance issue on a server running PostgreSQL 9.3.1 on Centos 5. The machine is a dual quad-core Xeon E5620 with 24GB ECC RAM and four enterprise SATA Seagate Constellation ES drives configured as 2 software RAID1 volumes. The main DB is on one volume a

[PERFORM] Kernel cache vs shared_buffers

2007-05-12 Thread Michael van Rooyen
We're in the process of upgrading our db server's memory from 2GB to 8GB to improve access performance. This is a dedicated dual Xeon db server not running any significant non-db processes. Our database size on disk is ~11GB, although we expect it to grow to ~20GB. Much of this data is inact