[jira] Assigned: (DERBY-4079) Add support for SQL:2008 and to limit result set cardinality

["Dag H. Wanvik (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-4079?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dag H. Wanvik reassigned DERBY-4079:
------------------------------------

    Assignee: Dag H. Wanvik

> Add support for SQL:2008 <result offset clause> and <fetch first clause> to limit result set cardinality
> --------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4079
>                 URL: https://issues.apache.org/jira/browse/DERBY-4079
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Dag H. Wanvik
>            Assignee: Dag H. Wanvik
>
> SQL 2008 has added new syntax to support a direct way to limit the
> returned set of rows in a result set.  This allows an application to
> retrieve only some rows of an otherwise larger result set, similar to
> the popular LIMIT clauses use in some databases.
> Up till now, in Derby (and SQL) we have had to use the ROW_NUMBER()
> function in a nested subquery to achieve the effect of the <fetch
> first clause>, cf. DERBY-2998, a method which is rather more indirect
> and still not efficient (DERBY-3505), and primarily intended for OLAP
> functionality, perhaps.
> There has been no direct way to achieve the effect of the <result
> offset clause> via SQL.
> Syntax (cf. SQL 2008, section 7.13):
>        <result offset clause> ::= OFFSET <n> {ROW | ROWS}
>        <fetch first clause> ::=      FETCH {FIRST | NEXT} [<n>] {ROW | ROWS} ONLY
> where <n> is an integer. It syntactically follows the ORDER BY
> clause. 
> Note that both ORDER BY and the new clauses above are allowed also in
> subqueries in the new version of the SQL standard (section 7.13). I
> only propose to include this at the top level in DERBY for now. (ORDER
> BY is presently also not allowed in subqueries in Derby since SQL
> didn't allow for this until SQL 2008 either).

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