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Date: Sat, 29 Sep 2012 05:27:07 +1100 (NCT)
From: "Mamta A. Satoor (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Message-ID: <640333772.140410.1348856827593.JavaMail.jiratomcat@arcas>
Subject: [jira] [Updated] (DERBY-4831) Support for auto-calculated (virtual)
 columns
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     [ https://issues.apache.org/jira/browse/DERBY-4831?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mamta A. Satoor updated DERBY-4831:
-----------------------------------

    Urgency: Low
     Labels: derby_triage10_10  (was: )
    
> Support for auto-calculated (virtual) columns
> ---------------------------------------------
>
>                 Key: DERBY-4831
>                 URL: https://issues.apache.org/jira/browse/DERBY-4831
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 10.6.1.0
>            Reporter: Uriah Eisenstein
>              Labels: derby_triage10_10
>
> The suggestion is similar to generated columns, but with the column value not actually stored in the database, but rather recalculated whenever the column is accessed.
> This saves storage space in return for additional processing.
> It is also suggested to support creating indices on the calculated columns; this could be a partial solution to expression-based indexes (Derby-455). For instance, creating an index on an expression such as "upper (column)" requires Derby to recognize the expression in a query involving the column, so that it could take advantage of the index; this could be difficult for more complex expressions. Using a generated column would double the required storage for the original column. An auto-computed column could solve both problems.
> (I don't know if there is any standard SQL syntax for defining such columns)

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