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https://issues.apache.org/jira/browse/HIVE-11573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16513432#comment-16513432
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Zoltan Haindrich commented on HIVE-11573:
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[~gopalv] I see that the goal here was to prevent the conversion of smaller
(a=1 || a=2) to a IN (1,2) expressions
but right now I'm tempted to to set the min value to 2 or 3; because handling
of INs have been improved ever since - I think the original reason behind this
ticket might have been gone...and to make really use of CALCITE-2247 I've to
enable decomposition of all INs to ORs as a preprocessing step - but I think it
makes sens to convert them back to INs in PointLookupOptimizer - because it
will make the stats estimation probably more sane...
Do you have any concers...or any recommendations to keep an eye for?
> PointLookupOptimizer can be pessimistic at a low nDV
> ----------------------------------------------------
>
> Key: HIVE-11573
> URL: https://issues.apache.org/jira/browse/HIVE-11573
> Project: Hive
> Issue Type: Bug
> Affects Versions: 2.0.0
> Reporter: Gopal V
> Assignee: Gopal V
> Priority: Major
> Fix For: 2.0.0
>
> Attachments: HIVE-11573.1.patch, HIVE-11573.2.patch,
> HIVE-11573.3.patch, HIVE-11573.4.patch, HIVE-11573.5.patch, HIVE-11573.6.patch
>
>
> The PointLookupOptimizer can turn off some of the optimizations due to its
> use of tuple IN() clauses.
> Limit the application of the optimizer for very low nDV cases and extract the
> sub-clause as a pre-condition during runtime, to trigger the simple column
> predicate index lookups.
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