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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DERBY-6134) Faster, incremental implementation of DISTINCT in presence of FETCH NEXT clause
Date Mon, 01 Apr 2013 03:07:15 GMT
Dag H. Wanvik created DERBY-6134:
------------------------------------

             Summary: Faster, incremental implementation of DISTINCT in presence of FETCH
NEXT clause
                 Key: DERBY-6134
                 URL: https://issues.apache.org/jira/browse/DERBY-6134
             Project: Derby
          Issue Type: Improvement
          Components: SQL
            Reporter: Dag H. Wanvik
            Priority: Minor


DISTINCT queries with a FETCH NEXT clause can be made faster
by using a hash table rather than the current sorting of all rows, cf. the slow query seen
by a user in DERBY-6132, at least if the number of rows fetched by the clause is a (low) fraction
of the total number of rows and the has table would fit in memory.


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