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https://issues.apache.org/jira/browse/DERBY-4831?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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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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