Re: [PERFORM] memory question

2010-03-25 Thread Dave Crooke
What Scott said ... seconded, all of it. I'm running one 500GB database on a 64-bit, 8GB VMware virtual machine, with 2 vcores, PG 8.3.9 with shared_buffers set to 2GB, and it works great. However, it's a modest workload, most of the database is archival for data mining, and the working set for

Re: [PERFORM] memory question

2010-03-25 Thread Matthew Wakeling
On Wed, 24 Mar 2010, Campbell, Lance wrote: I have 24 Gig of memory on my server... Our server manager seems to think that I have way to much memory. He thinks that we only need 5 Gig. You organisation probably spent more money getting your server manager to investigate how much RAM you

[PERFORM] Why Wal_buffer is 64KB

2010-03-25 Thread Tadipathri Raghu
Hi All, Can anybody clarify on this, why wal_buffer is 64kb and what is advantages and disadvantages in increasing or decreasing the wal_buffer. Regards Raghav

Re: [PERFORM] default_statistics_target

2010-03-25 Thread Robert Haas
On Mon, Mar 22, 2010 at 6:19 PM, Carlo Stonebanks stonec.regis...@sympatico.ca wrote: Thanks for the insight. How much more of a server's resources will be consumed by an ANALYZE with default_statistics_target = 100? I don't think it will be much of a problem, especially since autovacuum will

Re: [PERFORM] Why Wal_buffer is 64KB

2010-03-25 Thread Brad Nicholson
On Thu, 2010-03-25 at 20:31 +0530, Tadipathri Raghu wrote: Hi All, Can anybody clarify on this, why wal_buffer is 64kb and what is advantages and disadvantages in increasing or decreasing the wal_buffer. This is addressed in the documentation.

Re: [PERFORM] Why Wal_buffer is 64KB

2010-03-25 Thread Jaime Casanova
On Thu, Mar 25, 2010 at 11:01 AM, Tadipathri Raghu traghu@gmail.com wrote: Hi All, Can anybody clarify on this, why wal_buffer is 64kb and what is advantages and disadvantages in increasing or decreasing the wal_buffer. is 64kb just because by default we have low values in almost

Re: [PERFORM] Why Wal_buffer is 64KB

2010-03-25 Thread Pierre C
If you do large transactions, which emits large quantities of xlog, be aware that while the previous xlog segment is being fsynced, no new writes happen to the next segment. If you use large wal_buffers (more than 16 MB) these buffers can absorb xlog data while the previous segment is

[PERFORM] tuning auto vacuum for highly active tables

2010-03-25 Thread Bhella Paramjeet-PFCW67
Hi All, We have a postgres database in which couple of tables get bloated due to heavy inserts and deletes. Auto vacuum is running. My question is how can I make auto vacuum more aggressive? I am thinking of enabling autovacuum_vacuum_cost_delay and autovacuum_vacuum_cost_limit parameters.

Re: [PERFORM] mysql to postgresql, performance questions

2010-03-25 Thread Hannu Krosing
On Wed, 2010-03-24 at 09:55 +0100, Yeb Havinga wrote: Greg Smith wrote: Tom Lane wrote: So has anyone looked at porting MythTV to PG? Periodically someone hacks together something that works, last big effort I'm aware of was in 2006, and then it bit rots away. I'm sure we'd

Re: [PERFORM] mysql to postgresql, performance questions

2010-03-25 Thread James Mansion
Hannu Krosing wrote: Pulling the plug should not corrupt a postgreSQL database, unless it was using disks which lie about write caching. Didn't we recently put the old wife's 'the disks lied' tale to bed in favour of actually admiting that some well known filesystems and saftware raid

Re: [PERFORM] mysql to postgresql, performance questions

2010-03-25 Thread Scott Marlowe
On Thu, Mar 25, 2010 at 2:04 PM, James Mansion ja...@mansionfamily.plus.com wrote: Hannu Krosing wrote: Pulling the plug should not corrupt a postgreSQL database, unless it was using disks which lie about write caching. Didn't we recently put the old wife's 'the disks lied' tale to bed in

Re: [PERFORM] mysql to postgresql, performance questions

2010-03-25 Thread Pierre C
Hannu Krosing wrote: Pulling the plug should not corrupt a postgreSQL database, unless it was using disks which lie about write caching. Didn't we recently put the old wife's 'the disks lied' tale to bed in favour of actually admiting that some well known filesystems and saftware raid

Re: [PERFORM] mysql to postgresql, performance questions

2010-03-25 Thread Scott Marlowe
On Thu, Mar 25, 2010 at 2:29 PM, Pierre C li...@peufeu.com wrote: Hannu Krosing wrote: Pulling the plug should not corrupt a postgreSQL database, unless it was using disks which lie about write caching. Didn't we recently put the old wife's 'the disks lied' tale to bed in favour of actually

[PERFORM] experiments in query optimization

2010-03-25 Thread Faheem Mitha
Hi everyone, I've been trying to reduce both memory usage and runtime for a query. Comments/suggestions gratefully received. Details are at http://bulldog.duhs.duke.edu/~faheem/snppy/opt.pdf See particularly Section 1 - Background and Discussion. If you want a text version, see

Re: [PERFORM] mysql to postgresql, performance questions

2010-03-25 Thread Yeb Havinga
Scott Marlowe wrote: On Thu, Mar 25, 2010 at 2:29 PM, Pierre C li...@peufeu.com wrote: Hannu Krosing wrote: Pulling the plug should not corrupt a postgreSQL database, unless it was using disks which lie about write caching. Didn't we recently put the old wife's 'the disks

Re: [PERFORM] Performance Tuning Large PL/PGSQL Stored Procedure

2010-03-25 Thread Merlin Moncure
On Tue, Mar 23, 2010 at 5:00 PM, Eliot Gable egable+pgsql-performa...@gmail.com wrote: The complex type contains roughly 25 fields, mostly text, plus another 10 REFCURSORs. How many rows min/max/avg are coming back in your refcursors? Are you using cursors in order to return multiple complex

Re: [PERFORM] Why Wal_buffer is 64KB

2010-03-25 Thread Tadipathri Raghu
Hi Pierre, First of all , I Thank all for sharing the information on this Issue. On Thu, Mar 25, 2010 at 11:44 PM, Pierre C li...@peufeu.com wrote: If you do large transactions, which emits large quantities of xlog, be aware that while the previous xlog segment is being fsynced, no new

Re: [PERFORM] Performance Tuning Large PL/PGSQL Stored Procedure

2010-03-25 Thread Eliot Gable
On Thu, Mar 25, 2010 at 10:00 PM, Merlin Moncure mmonc...@gmail.com wrote: On Tue, Mar 23, 2010 at 5:00 PM, Eliot Gable egable+pgsql-performa...@gmail.com egable%2bpgsql-performa...@gmail.com wrote: The complex type contains roughly 25 fields, mostly text, plus another 10 REFCURSORs. How

[PERFORM] good effective_io_concurrency for FusionIO drives?

2010-03-25 Thread Richard Yen
Hello, Wondering what's a good value for effective_io_concurrency when dealing with FusionIO drives...anyone have any experience with this? I know that SSDs vary from 10 channels to 30, and that 1 SSD about as fast as a 4-drive RAID, but I can't seem to settle on a good value to use for