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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-1471) Implement layer B streaming for new methods defined in JDBC4.0
Date Wed, 13 Dec 2006 12:09:22 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1471?page=comments#action_12458092 ] 
Knut Anders Hatlen commented on DERBY-1471:

I have tested the lengthless versions of PreparedStatement.setClob(), PreparedStatement.setCharacterStream(),
PreparedStatement.setAsciiStream(), PreparedStatement.setBlob(), PreparedStatement.setBinaryStream(),
ResultSet.updateClob(), ResultSet.updateCharacterStream(), ResultSet.updateAsciiStream(),
ResultSet.updateBlob() and ResultSet.updateBinaryStream(), and they all seem to work without
throwing OutOfMemoryError for large lobs. Great! :)

However, compatibility with older servers seems to have been broken. When I try to stream
a lob (small enough to fit in the client's memory) to a server, I get a protocol
error: "java.sql.SQLException: A network protocol error was encountered and the connection
has been terminated: A PROTOCOL Data Stream Syntax Error was detected.  Reason: 0x0." I think
we need to check the version of the server before using layer b streaming. This could be done
in NetDatabaseMetaData.computeFeatureSet_().

Thank you for addressing my previous comments. My comment about readAndSetExtParam() was a
bit unclear. What I meant, was that the if-clause could be written as

  if (stream == null) {
    // same code as before for null
  } else if (stream instanceof LayerBStreamedEXTDTAReaderInputStream) {
    // new Layer B code
  } else {
    // same code as in the old else-clause

The main point is that we should have an "else" clause at the end which catches all cases,
instead of only having "if" and "else if" clauses. I think that it will make the code clearer,
since a reader doesn't have to figure out whether there are cases that don't match any of
the if/else-if clauses.

> Implement layer B streaming for new methods defined in JDBC4.0
> --------------------------------------------------------------
>                 Key: DERBY-1471
>                 URL: http://issues.apache.org/jira/browse/DERBY-1471
>             Project: Derby
>          Issue Type: New Feature
>          Components: Network Client
>            Reporter: Tomohito Nakayama
>         Assigned To: Tomohito Nakayama
>         Attachments: DERBY-1471.diff, DERBY-1471.patch, DERBY-1471.stat, DERBY-1471_2.patch,
DERBY-1471_2.stat, DERBY-1471_3.patch, DERBY-1471_3.stat, DERBY-1471_4.patch, DERBY-1471_4.stat
> JDBC 4.0 introduced new methods which take parameters for object to be sent to sever
without length information.
> For those methods, Layer B streaming is best way to implement sending object to server.
> This issue is representation of DERBY-1417 in Network Client.

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