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https://issues.apache.org/jira/browse/HIVE-18825?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16380727#comment-16380727
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Jesus Camacho Rodriguez commented on HIVE-18825:
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Cc [~sankarh], [~ekoifman]
> Define ValidTxnList before starting query optimization
> ------------------------------------------------------
>
> Key: HIVE-18825
> URL: https://issues.apache.org/jira/browse/HIVE-18825
> Project: Hive
> Issue Type: Improvement
> Components: Transactions
> Affects Versions: 3.0.0
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Priority: Major
>
> 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 compilation. There
> should not be any visible changes for end user.
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