[jira] [Updated] (DERBY-884) allow and use backward scans on indexes.

["Mamta A. Satoor (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-884?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mamta A. Satoor updated DERBY-884:
----------------------------------

    Urgency: Low
     Labels: derby_triage10_11  (was: )
    
> allow and use backward scans on indexes.
> ----------------------------------------
>
>                 Key: DERBY-884
>                 URL: https://issues.apache.org/jira/browse/DERBY-884
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL, Store
>    Affects Versions: 10.1.3.1
>            Reporter: Mike Matrigali
>            Priority: Minor
>              Labels: derby_triage10_11
>
> Improve the access interface to support backward scans, currently only forward scans are supported.
> Improve the btree implementation to support backward scans.  The structure could support this, the work just has not been done.  With
> row level locking, concurrent tree splitting, and current assumptions
> throughout the access method that scans go top/down, left to right the
> work to do a backward scan is harder than doing a forward scan.  Also
> once the store portion is done, there would be necessary changes to:
> optimizer, execution engine, and scan interface to allow the backward
> scan.  This would be a hard first project. 
> Improve the optimizer to understand derby indexes now support backward scans.
> Improve the execution engine to use the new backward scan interfaces to execute backward scans.

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