[jira] Reopened: (DERBY-772) Handle pushing IN predicates into UNIONs. This would allow use of index if present improving performance.

["Andrew McIntyre (JIRA)" <de...@db.apache.org>]

     [ http://issues.apache.org/jira/browse/DERBY-772?page=all ]
     
Andrew McIntyre reopened DERBY-772:
-----------------------------------


> Handle pushing IN predicates into UNIONs. This would allow use of index if present improving performance.
> ---------------------------------------------------------------------------------------------------------
>
>          Key: DERBY-772
>          URL: http://issues.apache.org/jira/browse/DERBY-772
>      Project: Derby
>         Type: Sub-task

>   Components: SQL
>     Versions: 10.0.2.0, 10.1.2.1, 10.2.0.0
>  Environment: generic
>     Reporter: Satheesh Bandaram
>      Fix For: 10.2.0.0, 10.1.2.2, 10.1.3.0
>  Attachments: DERBY-772.patch
>
> While fix for DERBY-649 allows pushing binary predicates into SELECT statements that are underneath a UNOIN, it would also be good to allow IN operations to be pushed. Derby can rewrite IN operations in a way to allow use of index, if present.
> Derby currently rewrites: REF IN (1, 2, 3) to REF >=1 and REF <=3 and hence would allow use of index on REF, if present. Pushing this predicate into Union would allow use of index on REF for queries like:
> Select * from 
>      (SELECT REF, NAME from T1 UNION ALL SELECT REF, NAME from t2)
> where REF IN (1,2,3)

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