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https://issues.apache.org/jira/browse/DERBY-4653?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kathey Marsden updated DERBY-4653:
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Summary: Avoid unnecessary round-trip for commit in the client driver
(was: Avoid unnecessary round-trip for commit/rollback in the client driver)
Lily recommends putting in the change first for commit and has filed a second
issue for rollback, That fix is perhaps not worth the change, because all open
result sets would need to be checked before optimizing out the rollback flow.
She filed another issue for rollback DERBY-4687
, so I am changing the summary for this issue to cover just commit. I looked
at the patch DERBY-4653-7_withflowcommittest.diff and I think it looks very
good except a couple of stale comments. I will attach the revised patch and
will commit Monday unless there are more comments.
> Avoid unnecessary round-trip for commit 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,
> DERBY-4653-5_withflowcommitrollback.diff,
> DERBY-4653-6_withflowcommitrollback.diff,
> DERBY-4653-7_withflowcommittest.diff, ReproTransInProgressAttempt.java,
> 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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