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https://issues.apache.org/jira/browse/HIVE-23052?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Work on HIVE-23052 started by Marton Bod.
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> Optimize lock enqueueing in TxnHandler
> --------------------------------------
>
> Key: HIVE-23052
> URL: https://issues.apache.org/jira/browse/HIVE-23052
> Project: Hive
> Issue Type: Improvement
> Reporter: Marton Bod
> Assignee: Marton Bod
> Priority: Major
>
> TxnHandler::enqueueLockWithRetry uses select for update (S4U) to retrieve the
> next lock id from the metastore. This locks the NEXT_LOCK_ID table for
> concurrent lock requests until the transaction has been committed.
> Since this creates contention, we should reduce the scope of this S4U,
> thereby locking the table for only as long as necessary. Currently, within
> the same txn, after the initial S4U, we also insert the transaction
> components (TXN_COMPONENTS table) before committing, even though they are
> independent and do not make use of the lock id. So factoring out these
> txn_component inserts should decrease the time the next_lock_id table is
> locked and thus increase concurrency.
>
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