[jira] [Commented] (CALCITE-1960) Duplicated mapping generated from RelMdPredicates

["Rheet Wong (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1960?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16158903#comment-16158903 ] 

Rheet Wong commented on CALCITE-1960:
-------------------------------------

[~julianhyde] Thanks for your suggestion, I have added test in RelMetadataTest.java. Please review it again, Thanks.

> Duplicated mapping generated from RelMdPredicates
> -------------------------------------------------
>
>                 Key: CALCITE-1960
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1960
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Rheet Wong
>            Assignee: Julian Hyde
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> When inferring pulled up predicates, multiple mappings are generated to 
> make sure equivalent expressions can be substitute. E.g., for an expression 
> 'a + b + c' and the following equivalences: 
> {code:sql}
> a : {a, b}
> b : {a, b}
> c : {c, e}
> {code}
> should generate:
> {code:sql}
> a + a + c
> a + a + e
> a + b + c
> a + b + e
> b + a + c
> b + a + e
> b + b + c
> b + b + e
> {code}
> The mapping generation is a typical permutation generation process. However, 
> the current code is not handling the permutation well, thus causing duplicated 
> mappings.



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