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Date: Mon, 21 Aug 2006 05:13:16 -0700 (PDT)
From: "Tomohito Nakayama (JIRA)" <derby-dev@db.apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-1559) when receiving a single EXTDTA
 object representing a BLOB, the server do not need to read it into memory
 before inserting it into the DB
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    [ http://issues.apache.org/jira/browse/DERBY-1559?page=comments#action_12429403 ] 
            
Tomohito Nakayama commented on DERBY-1559:
------------------------------------------

Well.....

If *you* don't think the difference of DerbyNetClient/parameterMapping.out is critically harmful,
which was introduced in DERBY-1535 before, I think it is OK for you to commit DERBY-1559. 

It is your judgement....

The background is that 
DERBY-1559 also would require the difference of DerbyNetClient/parameterMapping.out and 
committing DERBY-1559 will strengthen the difference.

If you think difference of DerbyNetClient/parameterMapping.out is critically harmful, 
please do not commit patch of DERBY-1559 and wait for DERBY-1610.
Otherwise you would make unexpected reason for a problem against your will.

However opinion for that difference may differ betweeen people...
Then I left judge for you.

At least for me, through discussion in DERBY-1610, think already applied difference in DerbyNetClient/parameterMapping.out is unfinished and much more difference is needed.
and think it should be rollbacked and applied in once if possible.

> when receiving a single EXTDTA object representing a BLOB, the server do not need to read it into memory before inserting it into the DB
> ----------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-1559
>                 URL: http://issues.apache.org/jira/browse/DERBY-1559
>             Project: Derby
>          Issue Type: Sub-task
>          Components: Network Server
>    Affects Versions: 10.2.1.0, 10.3.0.0, 10.2.2.0
>            Reporter: Andreas Korneliussen
>         Assigned To: Andreas Korneliussen
>         Attachments: DERBY-1559.diff, DERBY-1559.stat, DERBY-1559v2.diff, serverMemoryUsage.xls
>
>
> When streaming a BLOB from the Network Client to the Network Server, the Network server currently read all the data from the stream and put it into a byte array.
> The blob data is then inserted into the DB by using
> PreparedStatement.setBytes(..)
> and later
> PreparedStatement.execute()
> To avoid OutOfMemoryError if the size of the Blob is > than total memory in the VM, we could make the network server create a stream which reads data when doing PreparedStatement.execute().  The DB will then stream the BLOB data directly from the network inputstream into the disk.
> I intent to make a patch which does this if there is only one EXTDTA object (BLOB) sent from the client in the statement, as it will simplify the implementation. Later this can be improved  further to include CLOBs, and possibly to include the cases where there are multiple EXTDTA objects.
> --
> CLOBs are more complex, as there need to be some character encoding. This can be achieved by using a InputStreamReader,  and use PreparedStatement.setCharacterStream(..). However the size of the stream is not necessarily the same as the size of the raw binary data, and to do this for CLOBs, I would need the embedded prepared statements to support the new setCharacterStream() overloads in JDBC4 (which do not include a length atribute)
> --
> Multiple EXTDATA objects are also more complex, since one would need to have fully read the previous object ,before it is possible to read the next.
> --

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