Re: PostgreSQL 8.4 performance tuning questions

Unfortunately had to downgrade back to 8.3. Now having troubles with
that and still solving them.

For future upgrade, what is the basic steps?

>Was the database analyzed recently?
Hm... there was smth like auto analyzer in serverlog when i started it
first time, but i didn't mention that.
Should I analyze whole db? How to do it?

And how should I change _cost variables?

I/O was very high. at first memory usage grew up and then began to full swap.

2009/7/30 <tv(at)fuzzy(dot)cz>:
>> Hi, list. I've just upgraded pgsql from 8.3 to 8.4. I've used pgtune
>> before and everything worked fine for me.
>>
>> And now i have ~93% cpu load. Here's changed values of config:
>>
>> default_statistics_target = 50
>> maintenance_work_mem = 1GB
>> constraint_exclusion = on
>> checkpoint_completion_target = 0.9
>> effective_cache_size = 22GB
>> work_mem = 192MB
>> wal_buffers = 8MB
>> checkpoint_segments = 16
>> shared_buffers = 7680MB
>> max_connections = 80
>>
>>
>> My box is Nehalem 2xQuad 2.8 with RAM 32Gb, and there's only
>> postgresql working on it.
>>
>> For connection pooling i'm using pgbouncer's latest version with
>> pool_size 20 (used 30 before, but now lowered) and 10k connections.
>>
>> What parameters i should give more attention on?
>>
>
> All the values seem quite reasonable to me. What about the _cost variables?
>
> I guess one or more queries are evaluated using a different execution
> plan, probably sequential scan instead of index scan, hash join instead of
> merge join, or something like that.
>
> Try to log the "slow" statements - see "log_min_statement_duration". That
> might give you slow queries (although not necessarily the ones causing
> problems), and you can analyze them.
>
> What is the general I/O activity? Is there a lot of data read/written to
> the disks, is there a lot of I/O wait?
>
> regards
> Tomas
>
> PS: Was the database analyzed recently?
>
>