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Manish Khettry commented on DERBY-681: -------------------------------------- OK. Do you think it makes sense to mark this bug as resolved and another to track this issue. Either way is fine. > Eliminate the parser's rewriting of the abstract syntax tree for queries with > GROUP BY and/or HAVING clauses > ------------------------------------------------------------------------------------------------------------ > > Key: DERBY-681 > URL: https://issues.apache.org/jira/browse/DERBY-681 > Project: Derby > Issue Type: Improvement > Components: SQL > Reporter: Rick Hillegas > Assigned To: Manish Khettry > Attachments: 681.patch.txt, 681.patch2.txt, 681.patch3.txt, notes.txt > > > 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. - You can reply to this email to add a comment to the issue online.