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https://issues.apache.org/jira/browse/HIVE-13250?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15204859#comment-15204859
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Gopal V commented on HIVE-13250:
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bq. I'd expect the cast to change the value to whatever can be compared
directly against storage.
UDFs disable all predicate pushdown. Only constants are applied to PPD, so
retaining the UDFToString disabled all PPD into the storage system.
> Compute predicate conversions on the client, instead of per row group
> ---------------------------------------------------------------------
>
> Key: HIVE-13250
> URL: https://issues.apache.org/jira/browse/HIVE-13250
> Project: Hive
> Issue Type: Improvement
> Affects Versions: 2.1.0
> Reporter: Siddharth Seth
> Assignee: Ashutosh Chauhan
> Attachments: HIVE-13250.2.patch, HIVE-13250.patch
>
>
> When running a query for the form
> select count from table where ts_field = "2016-01-23 00:00:00";
> or
> select count from table where ts_field = 1453507200
> ts_field is of type TIMESTAMP
> The predicate is converted to whatever format is appropriate for TIMESTAMP
> processing on each and every row group.
> It would be far more efficient to process this once on the client - or even
> once per task.
> The same applies to ORC splt elimination as well - this is applied for each
> stripe.
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