Re: High update activity, PostgreSQL vs BigDBMS

Dave Cramer wrote:

>>
>> The box has 3 GB of memory.  I would think that BigDBMS would be hurt
>> by this more than PG.  Here are the settings I've modified in
>> postgresql.conf:
>
> As I said you need to set shared_buffers to at least 750MB this is the
> starting point, it can actually go higher. Additionally effective cache
> should be set to 2.25 G turning fsync is not a real world situation.
> Additional tuning of file systems can provide some gain, however as
> Craig pointed out some queries may need to be tweaked.

Dave, thanks for the hard numbers, I'll try them.  I agree turning fsync
off is not a production option.  In another reply to my original
posting, Alex mentioned that BigDBMS gets an advantage from its async
IO.  So simply as a test, I turned fsync off in an attempt to open wide
all the pipes.

Regarding shared_buffers=750MB, the last discussions I remember on this
subject said that anything over 10,000 (8K buffers = 80 MB) had unproven
benefits.  So I'm surprised to see such a large value suggested.  I'll
certainly give it a try and see what happens.

>>
>> autovacuum=on
>> stats_row_level = on
>> max_connections = 10
>> listen_addresses = 'db01,localhost'
>> shared_buffers = 128MB
>> work_mem = 16MB
>> maintenance_work_mem = 64MB
>> temp_buffers = 32MB
>> max_fsm_pages = 204800
>> checkpoint_segments = 30
>> redirect_stderr = on
>> log_line_prefix = '%t %d'
--
Guy Rouillier