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From "Zoltan Haindrich (JIRA)" <>
Subject [jira] [Commented] (HIVE-11573) PointLookupOptimizer can be pessimistic at a low nDV
Date Fri, 15 Jun 2018 06:40:00 GMT


Zoltan Haindrich commented on HIVE-11573:

[~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:
>             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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