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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Created: (DERBY-4123) Improve query plan output by including table alias name along with the table names.
Date Fri, 27 Mar 2009 03:13:50 GMT
Improve query plan output by including table alias name along with the table names.
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                 Key: DERBY-4123
                 URL: https://issues.apache.org/jira/browse/DERBY-4123
             Project: Derby
          Issue Type: Improvement
          Components: Miscellaneous
            Reporter: Mamta A. Satoor
            Priority: Minor


Derby allows user to look at a query plan by 
call SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(1)
run the query
VALUES SYSCS_UTIL.SYSCS_GET_RUNTIMESTATISTICS()

If the query involved does a self jon, in the query plan, we do not distinguish between the
tables. For instance, for the query below
SELECT table1.id, m0.value, m1.value FROM table1, table2 m0, table2 m1 WHERE table1.id=m0.id
AND m0.name ='PageSequenceId' AND table1.id=m1.id AND m1.name='PostComponentId' AND m1.value='21857'
ORDER BY m0.value;
when we print the info on the query plan, both instances of table2 which are m0 and m1 are
referred in the plan as simply table2. It will be good for us to include the alias name as
well to know exactly which table is involved.

The query above along with the tables and related index creation can be found in DERBY-3926
(attachment derby-reproduce.zip)

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