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https://issues.apache.org/jira/browse/DERBY-5426?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rick Hillegas updated DERBY-5426:
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Attachment: derby-5426-01-aa-improveError.diff
Attaching derby-5426-01-aa-improveError.diff. This patch improves error
reporting for high contention sequences/identities. I am running regression
tests now.
This patch makes the following changes:
1) The "too much contention" message (X0Y84) now recommends that the user try
adjusting the two properties.
2) To clarify the code, error raising has been moved inside the retry loop in
SequenceUpdater.getCurrentValueAndAdvance().
3) The two SequenceUpdaters now raise different exceptions when they have
looped too long trying to get the next value from the sequence generator. The
sequence SequenceUpdater continues to raise a "too much contention" exception
just as it used to. The identity SequenceUpdater now raises a "lock timeout"
exception (40XL1) which wraps a "too much contention" exception.
Touches the following files:
M java/engine/org/apache/derby/impl/sql/catalog/SequenceUpdater.java
M java/engine/org/apache/derby/loc/messages.xml
> Improve the error raised by too much contention on a sequence/identity.
> -----------------------------------------------------------------------
>
> Key: DERBY-5426
> URL: https://issues.apache.org/jira/browse/DERBY-5426
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 10.8.2.1, 10.9.0.0
> Reporter: Rick Hillegas
> Assignee: Rick Hillegas
> Attachments: derby-5426-01-aa-improveError.diff
>
>
> Currently, when there is too much contention on a sequence/identity, Derby
> raises an error saying so. There are two properties which the user can adjust
> in order to reduce the risk of this error:
> derby.locks.waitTimeout
> derby.language.sequence.preallocator
> It would be good to point the user at these knobs. The following change would
> improve this error reporting:
> 1) Raise a lock timeout SQLException
> 2) Chain a "too much contention" SQLException (X0Y84) to the lock timeout.
> 3) Make the "too much contention" exception suggest that the user adjust the
> properties mentioned above.
> To make the code easier to understand, the exception raising could replace
> the loop exit inside the following "if" block in
> SequenceUpdater.getCurrentValueAndAdvance():
> if (
> (_lockTimeoutInMillis >= 0L) &&
> ( (System.currentTimeMillis() - startTime.longValue()) >
> _lockTimeoutInMillis )
> )
> {
> break;
> }
> This approach was recommended by the discussion on DERBY-5423.
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