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https://issues.apache.org/jira/browse/HIVE-17710?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16283752#comment-16283752
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Eugene Koifman commented on HIVE-17710:
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I think locks are more useful for operations that that could work in either
order. For example, if you wanted Truncate or Insert Overwrite to be a mutexed
operation, it would acquire X locks which only works if everyone else acquires
(at least) an S lock. Either ordering of IOW and Select could be meaningful
but not so much with drop and Select.
The only thing I wanted to change in this patch is that we only apply locks
(exactly as we currently do) only for Managed Tables.
You agreed about External tables and views.
Materialized views are built versioned so that you can build a new snapshot
while an existing one is used to answer queries. cc [~jcamachorodriguez]
I assumed that Index tables are treated like indexes rather than 1st class
objects. Is that not true?
> LockManager should only lock Managed tables
> -------------------------------------------
>
> Key: HIVE-17710
> URL: https://issues.apache.org/jira/browse/HIVE-17710
> Project: Hive
> Issue Type: New Feature
> Components: Transactions
> Reporter: Eugene Koifman
> Assignee: Eugene Koifman
> Attachments: HIVE-17710.01.patch
>
>
> should the LM take locks on External tables? Out of the box Acid LM is being
> conservative which can cause throughput issues.
> A better strategy may be to exclude External tables but enable explicit "lock
> table/partition <lock mode>" command (only on external tables?).
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