| Subject | Re: [firebird-support] Re: Performance of Firebird vs. other DBMS |
|---|---|
| Author | David Johnson |
| Post date | 2005-08-17T13:17:37Z |
On Wed, 2005-08-17 at 13:09 +0000, laurenz_brein wrote:
max. Firebird opted for unidirectional indexes (like DB2, which is a
locking database).
A descending index finds the most likely candidate first, and then if
there are issues it can go to the next most likely candidate.
Use ascending indexes for min (), and descending indexes for max() in
any system with unidirectional indexes.
> The article did not make it clear to me why a SELECT MAX() couldAn ascending index would have to be traversed backwards to get a true
> not profit from an ascending index.
max. Firebird opted for unidirectional indexes (like DB2, which is a
locking database).
A descending index finds the most likely candidate first, and then if
there are issues it can go to the next most likely candidate.
Use ascending indexes for min (), and descending indexes for max() in
any system with unidirectional indexes.