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https://issues.apache.org/jira/browse/HIVE-9199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14257712#comment-14257712
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Alan Gates commented on HIVE-9199:
----------------------------------
+1. I didn't actually write this code, I just moved it to DummyTxnManager from
Driver. But looking over the patch, it makes sense. Completeness doesn't have
any meaning for DDL, only for DML.
> 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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