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From "Gopal V (JIRA)" <>
Subject [jira] [Commented] (HIVE-18825) Define ValidTxnList before starting query optimization
Date Thu, 01 Mar 2018 04:56:00 GMT


Gopal V commented on HIVE-18825:

	at org.apache.hadoop.hive.ql.lockmgr.DbTxnManager.getValidTxns(
	at org.apache.hadoop.hive.ql.Driver.recordValidTxns(
	at org.apache.hadoop.hive.ql.Driver.compile(

> Define ValidTxnList before starting query optimization
> ------------------------------------------------------
>                 Key: HIVE-18825
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Transactions
>    Affects Versions: 3.0.0
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>            Priority: Major
>         Attachments: HIVE-18825.patch
> Consider a set of tables used by a materialized view where inserts happened after the
materialization was created. To compute incremental view maintenance, we need to be able
to filter only new rows from those base tables. That can be done by inserting a filter
operator with condition e.g. {{ROW\_\_ID.transactionId < highwatermark and ROW\_\_ID.transactionId
NOT IN(<open txns>)}} on top of the MVs query definition and triggering the rewriting
(which should in turn produce a partial rewriting). However, to do that, we need to have a
value for {{ValidTxnList}} during query compilation so we know the snapshot that we are querying.
> This patch aims to generate {{ValidTxnList}} before query optimization. There should
not be any visible changes for end user.

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