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From "Kathey Marsden (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-326) Improve streaming of large objects for network server and client
Date Tue, 31 May 2005 10:46:53 GMT
Improve streaming of large objects for network server and client

         Key: DERBY-326
         URL: http://issues.apache.org/jira/browse/DERBY-326
     Project: Derby
        Type: Improvement
  Components: Network Server, Network Client, Performance  
    Reporter: Kathey Marsden

Currently the stream writing  methods in network server and client require a  length parameter.
This means that we have to get the length of the stream before sending it. For example in
network server in EXTDTAInputStream we have to use getString and getbytes() instead of getCharacterStream
and getBinaryStream so that we can get the  length.

SQLAM Level 7 provides for the enhanced LOB processing to allow streaming without indicating
the length, so, the writeScalarStream methods in
network server DDMWriter.java and network client Request.java can be changed to not require
a length.

Code inspection of these methods seems to indicate that while the length is never written
it is used heavily in generating the DSS. One strange thing is that it appears on error, the
stream is padded out to full length with zeros, but an actual exception is never sent.  Basically
I think perhaps these methods need to be rewritten from scratch based on the spec requirements
for lobs.

After the writeScalarStream methods have been changed, then EXTDAInputStream can be changed
to properly stream LOBS. See TODO tags in this file for more info.  I am guessing similar
optimizations available in the client as well, but am not sure where that code is.

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