On Wed, Jul 7, 2010 at 4:06 PM, Ryan Wexler <ryan@xxxxxxxxxxxxxxxx> wrote: > Postgresql was previously running on a single cpu linux machine with 2 gigs > of memory and a single sata drive (v8.3). Basically a desktop with linux on > it. I experienced slow performance. > > So, I finally moved it to a real server. A dually zeon centos machine with > 6 gigs of memory and raid 10, postgres 8.4. But, I am now experiencing even > worse performance issues. > > My system is consistently highly transactional. However, there is also > regular complex queries and occasional bulk loads. > > On the new system the bulk loads are extremely slower than on the previous > machine and so are the more complex queries. The smaller transactional > queries seem comparable but i had expected an improvement. Performing a db > import via psql -d databas -f dbfile illustrates this problem. It takes 5 > hours to run this import. By contrast, if I perform this same exact import > on my crappy windows box with only 2 gigs of memory and default postgres > settings it takes 1 hour. Same deal with the old linux machine. How is > this possible? > > Here are some of my key config settings: > max_connections = 100 > shared_buffers = 768MB > effective_cache_size = 2560MB > work_mem = 16MB > maintenance_work_mem = 128MB > checkpoint_segments = 7 > checkpoint_timeout = 7min > checkpoint_completion_target = 0.5 > > I have tried varying the shared_buffers size from 128 all the way to 1500mbs > and got basically the same result. Is there a setting change I should be > considering? > > Does 8.4 have performance problems or is this unique to me? > > thanks > > I think the most likely explanation is that the crappy box lied about fsync'ing data and your server is not. Did you purchase a raid card with a bbu? If so, can you set the write cache policy to write-back? -- Rob Wultsch wultsch@xxxxxxxxx -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
