Hello.
Thank you for your carefulness.
Please give your watch on DERBY-1610 and decide when you commit DERBY-1559.
Best regards.
Andreas Korneliussen (JIRA) wrote:
[ http://issues.apache.org/jira/browse/DERBY-1559?page=comments#action_12429406 ]
Andreas Korneliussen commented on DERBY-1559:
---------------------------------------------
I will wait for DERBY-1610 being fixed, to avoid the risk.
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.
--
--
/*
Tomohito Nakayama
[EMAIL PROTECTED]
[EMAIL PROTECTED]
[EMAIL PROTECTED]
Naka
http://www5.ocn.ne.jp/~tomohito/TopPage.html
*/
