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From V Narayanan <V.Naraya...@Sun.COM>
Subject Re: Network Client/Server BLOB
Date Tue, 27 Mar 2007 08:58:38 GMT
Kristian Waagan wrote:
> Raymond Kroeker wrote:
>> I have encountered some entries in the mailing list suggesting that 
>> large BLOB content is not supported when using the
>> network client/server.  By not supported I mean either the client or 
>> the server run out of memory when the content is
>> sufficiently large.
>> My own tests on version <> suggest that this 
>> is not the case; however I wanted to know if anyone can provide a
>> confirmation one way or another of this.  Thanks.
> Hello Raymond,
> From your mail I understand that you are able to use sufficiently 
> large BLOBs for you purpose with Derby in client/server mode.
> Would you mind telling us a little more about your use of Derby?
> Quite some work has been done to remove problems with LOB handling in 
> Derby, and more work is being done as we speek (implementing 
> LOCATOR-based handling of LOBs).
> That said, I'm not sure we are exactly where we want to be in Derby 
> A few questions;
>   1) How big are your BLOBs?
>   2) Do you both insert and retrieve them from/on the client?
>   3) What are your JVM settings? (heap size)
> As far as confirmation goes, I have tested embedded earlier with 2GB-1 
> LOBs without out-of-memory problems. 
"The org.apache.derby.jdbc.EmbeddedDriver doesn't have this problem." 
copied and pasted this from http://issues.apache.org/jira/browse/DERBY-550
> I am under the impression that stream data still has to be 
> materialized on the client before it is sent to the server.
> Can anyone else confirm this?
> Will the LOCATOR-work fix the issue?
Yes. The locator based implementation will fix this issue.

"The network client will request LOB columns to be sent as LOB Locators 
instead of data value bytes. Since the client no longer has a copy of 
the LOB data value bytes, operations on the LOB data will be performed 
on the server side, and the results of these operations will be sent to 
the client."

More information can be found here 

> regards,

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