Derby knows how to use an index to quickly find a minimum or a
maximum (by traversing down one side of the B-tree or the other).
It doesn't know how to do both in the same query, which would take
two traversals.
Is the work to fix this the same as making IN list use multiple probes,
and/or makeing OR lists do multiple probes? There are existing JIRA
items for those, or is it different enough to have a separate JIRA?
I believe they're different. While each case would use multiple
probes, in the MIN/MAX case one of the probes would go down the right
side of the BTree, while in the IN/OR case it would do "normal"
scans. Also, the MIN/MAX case and the IN/OR case would require
different logic to recognize when the optimizations are possible. The
costing logic in the optimizer would be different, too. It's possible
the two cases could share some execution code, but the rest of it
would require different implementations.
- Jeff Lichtman
[EMAIL PROTECTED]
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