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https://issues.apache.org/jira/browse/HIVE-13250?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15201819#comment-15201819
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Ashutosh Chauhan commented on HIVE-13250:
-----------------------------------------
I misunderstood this bug report. Without patch, filter expression for {{
ts_field = "2016-01-23 00:00:00"}} gets executed as {{(UDFToString(ts_field) =
'2016-01-23 00:00:00')}} In the patch I made changes such that cast is on
constant {{(ts_field = UDFTOTimeStamp('2016-01-23 00:00:00'))}} which gets
folded compile time to {{(ts_field = 2016-01-23 00:00:00.0)}}
However this is incorrect. Earlier behavior of cast on column is indeed
correct. I tested this on oracle, mysql & SQL Server all of which puts a cast
on column and not constant. [~sseth] Do you have anything else on the mind for
this one?
> 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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