[ http://issues.apache.org/jira/browse/DERBY-772?page=all ]
Satheesh Bandaram updated DERBY-772:
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Attachment: DERBY-772.patch
Add couple more tests.
> 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
> 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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