Re: Performance w/ multiple WHERE clauses

I am running pg 7.2 the PG reference build.

Thanks for the ANALYZE tip,  it led me to a answer.

This database gets a monthly update and it read only until the next 
update.  I ANALYZE once after each update.  Since the data does not 
change I should not need to ANALYZE again afterwards.

I mentioned this to the dbadmin that manages the data and found out one 
of the other users UPDATED some of the columns the morning that I was 
seeing this behavior.

I'll reANALYZE and see what happens.

Thanks,
-Aaron Held


Josh Berkus wrote:
> Aaron,
> 
> 
>>    # SET enable_seqscan to FALSE ;
>>    forced the use of an Index and sped things up greatly.
>>
>>I am not sure why it made the switch.  The load on the server seems to 
>>affect the performance, but I am seeing it more on the production server 
>>with 100 million rows as opposed to the development server with only 
>>about 6 million.  I need to buy more drives and develop on a larger data 
>>set.
> 
> 
> What version are you using?
> 
> I'd have 3 suggestions:
> 1) ANALYZE, ANALYZE, ANALYZE.  Then check if the row estimates made by EXPLAIN 
> seem accurate.
> 2) Modify your postgresql.conf file to raise the cost of seq_scans for parser 
> estimates.
> 3) Test this all again when 7.3 comes out, as parser estimate improves all the 
> time.
>