Re: Cursors performance

Might be worth doing a little test:

i) modify your code to fetch 1 row at a time
ii) set log_duration=true in your postgresql.conf (as the other posters 
have suggested)

Then compare with running the query in psql.

regards

Mark
 


Bill Chandler wrote:

>Thanks to all who have responded.  I now think my
>problem is not related to deleting/recreating indexes.
>Somehow it is related to JDBC cursors.  It appears
>that what is happening is that since I'm using 
>a fetch size of 5000, the command:
>
>FETCH FORWARD 5000 FROM JDBC_CURS_1
>
>is being repeatedly sent to the server as I process
>the result set from my query.  Each time this command
>is sent it it takes about 5 minutes to return which is
>about the amount of time the whole query took to
>complete before the performance degredation. So in
>other words it looks as if the full select is being
>rerun on each fetch.  
>
>Now the mystery is why is this happening all of the
>sudden?  I have been running w/ fetch size set to 5000
>for the last couple of weeks and it did not appear to
>be doing this (i.e. re-running the entire select 
>statement again).  Is this what I should expect when
>using cursors?  I would have thought that the server
>should "remember" where it left off in the query since
>the last fetch and continue from there.
>
>Could I have inadvertently changed a parameter
>somewhere that would cause this behavior?
>
>thanks,
>
>Bill
>
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