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https://issues.apache.org/jira/browse/HIVE-9199?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chaoyu Tang updated HIVE-9199:
------------------------------
Attachment: HIVE-9199.patch
The attached patch is to change DummayTxnManager to determine the lockMode for
DDL based on output writetype, while still using "complete" for DML operations.
Please help review on RB https://reviews.apache.org/r/29374/ , thanks in
advance.
> Excessive exclusive lock used in some DDLs with DummyTxnManager
> ---------------------------------------------------------------
>
> Key: HIVE-9199
> URL: https://issues.apache.org/jira/browse/HIVE-9199
> Project: Hive
> Issue Type: Bug
> Components: Locking
> Reporter: Chaoyu Tang
> Assignee: Chaoyu Tang
> Attachments: HIVE-9199.patch
>
>
> In DummyTxnManager, the lockMode for a WriteEntity (e.g. database, table) is
> determined by "complete" instead of its writeType. But since DDL output
> WriteEntity is usually complete, some DDL operations might be given exclusive
> locks which are actually not needed, which causes unnecessary locking
> contention. For example, in createTable, DummyTxnManager suggests an
> exclusive lock to table database writeentity since it is complete.
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