Re: Takes too long to fetch the data from database

soni de wrote:
> I have flushed the database, so currently records in the "lan" table are:
> 665280
> 
> but records can be increased more than 1GB and in that case it takes more
> than 1 hour
> 
> Below is explain analyze output taken from the table having 665280 records
> 
> pdb=# explain analyze SELECT sdate, stime, rbts from lan WHERE (
>  ( bname = 'pluto' ) AND ( cno = 17 ) AND ( pno = 1 ) AND ( ( sdate
>  >= '2004-07-21' ) AND ( sdate <= '2004-07-21' ) )  )  ORDER BY sdate, stime
> ;
> 
> NOTICE:  QUERY PLAN:
> Sort  (cost=17.13..17.13 rows=1 width=16) (actual time=619140.18..619140.29rows
> =288 loops=1)
>   ->  Index Scan using lan_pkey on lan  (cost=0.00..17.12 rows=1 width=16)
> (actual time=7564.44..619121.61 rows=288 loops=1)
> 
> Total runtime: 619140.76 msec

OK - there is clearly something wrong here when you take 10 minutes to 
fetch 288 rows from an index.

1. VACUUM FULL VERBOSE lan;
2. test again, and if that doesn't work...
3. REINDEX TABLE lan;
4. test again

I'm guessing you have a *lot* of dead rows in there.
-- 
   Richard Huxton
   Archonet Ltd