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From "Lily Wei (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4653) Avoid unnecessary round-trip for commit/rollback in the client driver
Date Tue, 25 May 2010 15:21:24 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12871194#action_12871194
] 

Lily Wei commented on DERBY-4653:
---------------------------------

Hi Knut:
     Thank you so much for the prompt response. I did svn update and up to revision 948072
and upgrade my jdk to 1.6.0_20.
For some reasons, the test in BooleanValuesTest is not running.

$ java junit.textui.TestRunner org.apache.derbyTesting.functionTests.tests.lang.B
ooleanValuesTest
..........
Time: 8.245

OK (10 tests)

$ java -version
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode, sharing)

$ svn update
At revision 948072.

> Avoid unnecessary round-trip for commit/rollback in the client driver
> ---------------------------------------------------------------------
>
>                 Key: DERBY-4653
>                 URL: https://issues.apache.org/jira/browse/DERBY-4653
>             Project: Derby
>          Issue Type: Improvement
>          Components: JDBC, Network Client
>    Affects Versions: 10.7.0.0
>            Reporter: Kristian Waagan
>            Assignee: Lily Wei
>            Priority: Minor
>         Attachments: DERBY-4653-1.diff
>
>
> The methods Connection.commit() and Connection.rollback() in the client driver cause
a round-trip to the server even if the commit/rollback is unnecessary (i.e. there is nothing
to commit or roll back).
> Comments suggest (see below) that this can be optimized, such that the commands are flowed
to the server only when required. It can be seen that this optimization has been used other
places in the client driver. Never the less, it must be checked that this optimization doesn't
have side-effects.
> This issue came up in connection with connection pooling, where a pool implementation
always issued a rollback to make sure there was no active transaction on the connection handed
out.
> From Connection.flowCommit:
>         // Per JDBC specification (see javadoc for Connection.commit()):
>         //   "This method should be used only when auto-commit mode has been disabled."
>         // However, some applications do this anyway, it is harmless, so
>         // if they ask to commit, we could go ahead and flow a commit.
>         // But note that rollback() is less harmless, rollback() shouldn't be used in
auto-commit mode.
>         // This behavior is subject to further review.
>         //   if (!this.inUnitOfWork)
>         //     return;
>         // We won't try to be "too smart", if the user requests a commit, we'll flow
a commit,
>         // regardless of whether or not we're in a unit of work or in auto-commit mode.
>         //

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