I've dealt with this problem but only from an Oracle perspective.
Using a
FORWARD_ONLY ScrollMode only allows the rs.next() method call. Any
other
result set record movement method call results in an exception.
This allows
JDBC to fetch x amount of records (set by fetch size) and then get
the next
fetch size etc. This prevents caching of previously fetched records
(causing
OOM with large result sets).
Since it is my understanding that Oracle sorts results and
generates
a cursor on the server side, if this really is a problem, somewhere
in the
code we are caching results.
The only way I have been able to scroll extremely large
results is
to implement paging. This does not imply that there is state
maintained. An
array of record pointers can do it and there are probably more ways.
I have no way to test this at home and I'm here all week.
My two cents.
John G.
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Sent: Monday, November 24, 2008 10:00 AM
To: hibernate-dev@lists.jboss.org
Subject: hibernate-dev Digest, Vol 29, Issue 16
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Today's Topics:
1. interesting issues in the forum (Sanne Grinovero)
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Message: 1
Date: Mon, 24 Nov 2008 17:17:58 +0100
From: "Sanne Grinovero" <[EMAIL PROTECTED]>
Subject: [hibernate-dev] interesting issues in the forum
To: "Hardy Ferentschik" <[EMAIL PROTECTED]>
Cc: Hibernate Dev <hibernate-dev@lists.jboss.org>
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain; charset=UTF-8
hi Hardy,
I've been browsing the forums today and found these topics of
interest,
they could be quite important bugs we should fix:
not working correctly with Spring (needs some test, I don't trust
this
report 100%)
http://forum.hibernate.org/viewtopic.php?t=988828
memory leak on redeploy (quite good information here, but this is
going to be hard)
http://forum.hibernate.org/viewtopic.php?p=2400319
sort + scrollableresult appears to load all in memory (never happened
to me, needs a test)
http://forum.hibernate.org/viewtopic.php?t=992342
I never used Spring, so can't help there.
I have no idea about how to solve the ThreadLocal problem: this has
to do
with
how Hibernate registers eventlisteners and we probably should ask for
changes there
Nnot sure if we can change the EM listeners without changing the
spec??
I'm absolutely no expert on other Hibernate modules.
I could try to reproduce the scrollableresult problem, but not this
week.
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