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https://issues.apache.org/jira/browse/HIVE-13622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15290196#comment-15290196
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Alan Gates commented on HIVE-13622:
-----------------------------------
+1
> WriteSet tracking optimizations
> -------------------------------
>
> Key: HIVE-13622
> URL: https://issues.apache.org/jira/browse/HIVE-13622
> Project: Hive
> Issue Type: Bug
> Components: Transactions
> Affects Versions: 1.3.0, 2.1.0
> Reporter: Eugene Koifman
> Assignee: Eugene Koifman
> Priority: Critical
> Attachments: HIVE-13622.2.patch, HIVE-13622.3.patch,
> HIVE-13622.4.patch
>
>
> HIVE-13395 solves the the lost update problem with some inefficiencies.
> 1. TxhHandler.OperationType is currently derived from LockType. This doesn't
> distinguish between Update and Delete but would be useful. See comments in
> TxnHandler. Should be able to pass in Insert/Update/Delete info from client
> into TxnHandler.
> 2. TxnHandler.addDynamicPartitions() should know the OperationType as well
> from the client. It currently extrapolates it from TXN_COMPONENTS. This
> works but requires extra SQL statements and is thus less performant. It will
> not work multi-stmt txns. See comments in the code.
> 3. TxnHandler.checkLock() see more comments around
> "isPartOfDynamicPartitionInsert". If TxnHandler knew whether it is being
> called as part of an op running with dynamic partitions, it could be more
> efficient. In that case we don't have to write to TXN_COMPONENTS at all
> during lock acquisition. Conversely, if not running with DynPart then, we
> can kill current txn on lock grant rather than wait until commit time.
> 4. TxnHandler.addDynamicPartitions() - the insert stmt here should combing
> multiple rows into single SQL stmt (but with a limit for extreme cases)
> 5. TxnHandler.enqueueLockWithRetry() - this currently adds components that
> are only being read to TXN_COMPONENTS. This is useless at best since read
> op don't generate anything to compact. For example, delete from T where t1
> in (select c1 from C) - no reason to add C to txn_components but we do.
>
> All of these require some Thrift changes
> Once done, re-enable TestDbTxnHandler2.testWriteSetTracking11()
> Also see comments in
> [here|https://issues.apache.org/jira/browse/HIVE-13395?focusedCommentId=15271712&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15271712]
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