Re: Very Bad Performance.

Dave Cramer wrote:

> Well, it's not quite that simple
>
> the rule of thumb is 6-10% of available memory before postgres loads
> is allocated to shared_buffers.
> then effective cache is set to the SUM of shared_buffers + kernel buffers
>
> Then you have to look at individual slow queries to determine why they
> are slow, fortunately you are running 7.4 so you can set
> log_min_duration to some number like 1000ms and then
> try to analyze why those queries are slow.

    I had that already set on my database , and when i look at the log
for all the problem queries, most of the queries are slow from one of
the table. when i look at the stats on that table they are really wrong,
not sure how to fix them. i run vacuumdb and analyze daily.

>
>
> Also hyperthreading may not be helping you..

    does it do any harm to the system if it is hyperthreaded ?

>
>
> Dave
>
> Pallav Kalva wrote:
>
>> Hi ,
>>
>>     I am experiencing a very bad performance on my production
>> database lately , all my queries are slowing down. Our application is
>> a webbased system with lot of selects and updates. I am running
>> "vacuumdb" daily on all the databases, are the below postgres
>> configuration parameters are set properly ? can anyone take a look.
>> Let me know if you need anymore information.
>>
>>
>> Postgres Version: 7.4
>> Operating System: Linux Red Hat 9
>> Cpus: 2 Hyperthreaded
>> RAM: 4 gb
>> Postgres Settings:
>> max_fsm_pages             | 20000
>> max_fsm_relations         | 1000
>> shared_buffers               | 65536
>> sort_mem                       | 16384
>> vacuum_mem                | 32768
>> wal_buffers                    | 64
>> effective_cache_size      | 393216
>>
>> Thanks!
>> Pallav
>>
>>
>> ---------------------------(end of broadcast)---------------------------
>> TIP 4: Don't 'kill -9' the postmaster
>>
>>
>