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https://issues.apache.org/jira/browse/DERBY-4653?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12876902#action_12876902
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Kathey Marsden commented on DERBY-4653:
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wrt to some of Kristian's comments and a few things I talked to Lily about
today.
I too think it would be good to test just for client and with regular,
pooled, and xa datasources.
I think if the test runs just for client we should always count on the
getTransactionID() method being there and can take out the skipping logic all
together. I think the system table query can come out all together. I tend to
think the getTransactionID() check is good enough, but the protocol trace
parsing would be ok too.
I agree the comment about embedded should come out of am.LogicalConnection.
For the flowRollback() change I think the condition to return if inUnitOfWork
should not be in the if block. I think the StatementPoolingTest failures you
were seeing with it set that way may be because the state of inUnitOfWork may
be wrong somehow where hold cursors and pooled connections are involved,
probably an existing issue that needs to be tracked down before committing this
change. Lily and I tried to reproduce it outside the test with the code but
we were not quite able to get in the same state as StatementPoolingTest.
> 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: _sds_0, DERBY-4653-1.diff, DERBY-4653-2.diff,
> DERBY-4653-3_withrollback.diff, DERBY-4653-4_withcommitrollbacktest.diff,
> SaveRoundClientDS.java, SaveRoundClientDS.java
>
>
> 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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