Re: setFetchSize() [Viruschecked] - Mailing list pgsql-jdbc

From Patric Bechtel
Subject Re: setFetchSize() [Viruschecked]
Date
Msg-id 20030717171322.C9CAECCA46@svr1.postgresql.org
Whole thread Raw
In response to Re: setFetchSize()  (Dmitry Tkach <dmitry@openratings.com>)
Responses Re: setFetchSize() [Viruschecked]
List pgsql-jdbc
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On Thu, 17 Jul 2003 13:01:43 -0400, Dmitry Tkach wrote:

Hello Dmitry,

that's exactly what the driver is doing if you do a setFetchSize(10).
Nevertheless, it won't solve the problem of the server eating HUGE amounts of memory if you do a "declare foo cursor
forselect * from myhugetable". It seems  
like postgresql locks all rows (or even copies them around in memory) until the connection drops again.

Patric

>Rich Cullingford wrote:

>> All,
>> Will this function be implemented in Release 7.4? I have several arge
>> tables that run Java out of memory when I attempt to load them through
>> JDBC. Any workarounds arppreciated...

>I was using cursors for a while as a workaround...
>Something like this:

>c.setAutocommit (false);
>Statement s = c.createStatement ();
>s.execute ("declare foo cursor for select * from bar");

>while (true)
>{
>    ResultSet rs = s.executeQuery ("fetch 10 from foo");
>    int count = 0;
>    while (rs.next ())
>    {
>        count++;
>        doStuffWithThisRow (rs);
>     }
>
>     if (count < 10) //The whole cursor contents has been processed
>          break;
>}
>
>
>I hope, it helps...

>Dima



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