From: | Dave Cramer <Dave(at)micro-automation(dot)net> |
---|---|
To: | Aaron Mulder <ammulder(at)alumni(dot)princeton(dot)edu> |
Cc: | pgsql-jdbc <pgsql-jdbc(at)postgresql(dot)org> |
Subject: | Re: Out of memory error on huge resultset |
Date: | 2002-10-11 14:30:30 |
Message-ID: | 1034346630.1796.74.camel@inspiron.cramers |
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Thread: | |
Lists: | pgsql-general pgsql-hackers pgsql-jdbc |
No disadvantage, in fact that is what we would like to do.
setFetchSize(size) turns on cursor support, otherwise fetch normally
Dave
On Fri, 2002-10-11 at 10:30, Aaron Mulder wrote:
> What would be the disadvantage of making the JDBC driver use a
> cursor under the covers (always)? Is it significantly slower or more
> resource-intensive than fetching all the data at once? Certainly it seems
> like it would save memory in some cases.
>
> Aaron
>
> On 10 Oct 2002, Dave Cramer wrote:
> > Nick,
> >
> > Use a cursor, the current driver doesn't support caching, the backend
> > gives you everything you ask for, you can't just say you want a limited
> > set.
> >
> > So if you use cursors you can fetch a subset
> >
> > Dave
> > On Thu, 2002-10-10 at 11:24, Nick Fankhauser wrote:
> > >
> > > I'm selecting a huge ResultSet from our database- about one million rows,
> > > with one of the fields being varchar(500). I get an out of memory error from
> > > java.
> > >
> > > If the whole ResultSet gets stashed in memory, this isn't really surprising,
> > > but I'm wondering why this happens (if it does), rather than a subset around
> > > the current record being cached and other rows being retrieved as needed.
> > >
> > > If it turns out that there are good reasons for it to all be in memory, then
> > > my question is whether there is a better approach that people typically use
> > > in this situation. For now, I'm simply breaking up the select into smaller
> > > chunks, but that approach won't be satisfactory in the long run.
> > >
> > > Thanks
> > >
> > > -Nick
> > >
> > > --------------------------------------------------------------------------
> > > Nick Fankhauser nickf(at)ontko(dot)com Phone 1.765.935.4283 Fax 1.765.962.9788
> > > Ray Ontko & Co. Software Consulting Services http://www.ontko.com/
> > >
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