Re: speeding up a query on a large table

Mike Rylander wrote:

>On 8/17/05, Manfred Koizar <mkoi-pg@aon.at> wrote:
>  
>
>>On Mon, 25 Jul 2005 17:50:55 -0400, Kevin Murphy
>><murphy@genome.chop.edu> wrote:
>>    
>>
>>>and because the number of possible search terms is so large, it
>>>would be nice if the entire index could somehow be preloaded into memory
>>>and encouraged to stay there.
>>>      
>>>
>>You could try to copy the relevant index
>>file(s) to /dev/null to populate the OS cache ...
>>    
>>
>
>That actually works fine.  When I had big problems with a large GiST
>index I just used cat to dump it at /dev/null and the OS grabbed it. 
>Of course, that was on linux so YMMV.
>
>  
>
Thanks, Manfred & Mike.  That is a very nice solution.  And just for the 
sake of the archive ... I can find the filename of the relevant index or 
table file name(s) by finding pg_class.relfilenode where 
pg_class.relname is the name of the entity, then doing, e.g.: sudo -u 
postgres find /usr/local/pgsql/data -name "somerelfilenode*".

-Kevin Murphy