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From Daniel John Debrunner <...@apache.org>
Subject Re: [jira] Commented: (DERBY-805) Push join predicates into union and other set operations. DERBY-649 implemented scalar (single table) predicate pushdown. Adding join predicate push down could improve performance significantly.
Date Thu, 16 Feb 2006 17:06:06 GMT
Army wrote:

> Jeff Lichtman (JIRA) wrote:

>> I would prefer to see any type of predicate pushed into a union - even
>> those containing complex expressions. This might be hard to implement,
>> though, as I don't know whether the cloning methods are implemented
>> for the entire ValueNode hierarchy.
> 
> 
> Sounds like an "itch" to me :) While it might indeed be nice to push
> predicates containing complex expressions, that's another enhancement of
> its own.  I won't be doing that with my DERBY-805 changes.

Right, sounds like a good approach, don't overload a single contained
change with other changes that add complexity and potentially make it
harder to review, and therefore harder to catch bugs.

Incremental development :-)

Dan.


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