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https://issues.apache.org/jira/browse/CALCITE-2247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16434518#comment-16434518
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Julian Hyde commented on CALCITE-2247:
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I thought about this some more. RexSimplify has predicates. Suppose after
you've seen {{a = 1}} you create a new RexSimplify with {{a = 1}} as a
predicate. Then you can simplify {{a = 1 OR a = 2}} to {{a = 1}}.
This way, we would be able to deal with more complex cases, e.g. simplify {{a >
10 and (a = 5 or a = 15)}} to {{a = 15}}.
There's a slight problem with this: it's very dependent on the order of the
items in the AND. We would not be able to optimize {{(a = 5 or a = 15) and a >
10}}, for instance. But we can live with that.
Whatever algorithm you choose, you should add tests to {{RexProgramTest}}. We
need to be able to test simplifications as unit tests, not just as part of
{{RelOptRulesTest}}.
> Add rule to push in condition condition into a related disjunctive expression
> -----------------------------------------------------------------------------
>
> Key: CALCITE-2247
> URL: https://issues.apache.org/jira/browse/CALCITE-2247
> Project: Calcite
> Issue Type: Improvement
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
>
> Simplify expressions like: {code}a = 1 AND (a = 1 OR a = 2){code} to {code}a
> = 1{code}
> Conditions to apply will be:
> * in an AND condition there exists a comparison(c) and an OR (o)
> * o and c only reference 1 variable
> See HIVE-19097 for more info.
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