Re: Memory exeception - Mailing list pgsql-jdbc

From Peter Wasem
Subject Re: Memory exeception
Date
Msg-id 3BEA4004.A015A242@itag.ch
Whole thread Raw
In response to Memory exeception  (Peter Wasem <peter.wasem@itag.ch>)
Responses Re: Memory exeception  ("Nick Fankhauser" <nickf@ontko.com>)
List pgsql-jdbc
Hi Barry

This is exactly what I observed. The physical memory dropped down to almost
zero (but no swap was used) before the exception was thrown. I'm not sure if I
can use cursors (other than ResultSet) since my application is Java-based.

Thanks

Barry Lind wrote:

> Peter,
>
> Postgres will return the entire result into memory first before
> processing the first row of data.  If you don't want this behavior you
> should use explicit cursors and fetch statements to get data a few rows
> at a time.  See the postgres documentation on the 'cursor' and 'fetch'
> sql statements.
>
> thanks,
> --Barry
>
> Peter Wasem wrote:
>
> > Hi
> >
> > I have a problem in processing large numbers of rows in ResultSets.
> > Here's the code fragment where the problem occurs:
> >
> > ...
> >     ResultSet rset = stmt.executeQuery( "select ... from ... where ...
> > order by ..." ) ;
> >     while(rset.next() )
> >     { // Process the row }
> > ...
> >
> > The query addresses some 100'000 rows. When stmt.executeQuery() is
> > executed suddenly an exception occurs.
> > The same program works fine with other JDBC drivers.
> >
> > Any ideas ?
> >
> > Greetings
> > Peter
> >
> > ---------------------------(end of broadcast)---------------------------
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> >     (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
> >

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