Re: Disk filling, CPU filling, renegade inserts and deletes?

From: Richard Plotkin <richard(at)richardplotkin(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Disk filling, CPU filling, renegade inserts and deletes?
Date: 2005-04-20 21:06:03
Message-ID: b155378a669f04e74f597d4b105c2a10@richardplotkin.com
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Hi Tom,

> Q: what have you got the FSM parameters set to?

Here's from postgresql.conf -- FSM at default settings.
# - Memory -

shared_buffers = 30400 # min 16, at least max_connections*2,
8KB each
work_mem = 32168 # min 64, size in KB
#maintenance_work_mem = 16384 # min 1024, size in KB
#max_stack_depth = 2048 # min 100, size in KB

# - Free Space Map -

#max_fsm_pages = 20000 # min max_fsm_relations*16, 6 bytes each
#max_fsm_relations = 1000 # min 100, ~50 bytes each

# - Kernel Resource Usage -

max_files_per_process = 750 #1000 # min 25
#preload_libraries = ''

> Q: what exactly is bloating? Without knowing which tables or indexes
> are growing, it's hard to speculate about the exact causes. Use du and
> oid2name, or look at pg_class.relpages after a plain VACUUM.

This I do not know. I've disabled the cron jobs and will let the
system bloat, then I will gather statistics (I'll give it 12-24 hours).

> It's likely that the real answer is "you need to vacuum more often
> than every six hours", but I'm trying not to jump to conclusions.

That could be it, except that I would expect the problem to then look
more like a gradual increase in CPU usage and a gradual increase in use
of disk space. Mine could be an invalid assumption, but the system
here looks like it goes from no problem to 100% problem within a
minute.

Thanks again!
Richard

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