[ http://issues.apache.org/jira/browse/DERBY-681?page=comments#action_12356724 ]
Satheesh Bandaram commented on DERBY-681: ----------------------------------------- Should this be marked an Enhancement request? While I agree the current scheme of rewriting the query can be improved, it does achieve the functionality. Bugs in the current implementation have been logged separately. (like DERBY-280) Changing the mechanism should be marked an Enhancement, I think. > Eliminate the parser's rewriting of the abstract syntax tree for queries with > GROUP BY and/or HAVING clauses > ------------------------------------------------------------------------------------------------------------ > > Key: DERBY-681 > URL: http://issues.apache.org/jira/browse/DERBY-681 > Project: Derby > Type: Improvement > Reporter: Rick Hillegas > > If a query contains a GROUP BY or HAVING clause, the parser rewrites the > abstract syntax tree, putting aggregates into a subselect and treating the > HAVING clause as the WHERE clause of a fabricated outer select from the > subquery. This allows the compiler to re-use some machinery since the HAVING > clause operates on the grouped result the way that the WHERE clause operates > on the from list. Unfortunately, this rewriting creates an explosion of > special cases in the compiler after parsing is done. The rewriting is not > systematically handled later on in the compiler. This gives rise to defects > like bug 280. We need to eliminate this special rewriting and handle the > HAVING clause in a straightforward way. This is not a small bugfix but is a > medium sized project. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
