Kbase P28458: Does Progress recommend using Oracle cost-based or rule-base
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
1/26/2005 |
|
Status: Unverified
GOAL:
Does Progress recommend using Oracle cost-based or rule-based optimization?
FACT(s) (Environment):
Oracle DataServer
FIX:
Oracle Rule-base vs cost-base optimization.
Progress has typically seen better (and more consistent) results using rule based. The hints generated by the DataServer are rule based. The DataServer was written before ORACLE offered cost based optimization (which, they are still making refinements to).
From past experiences, Progress has seen ORACLE make poor cost based choices when the statistics are not up to date on ALL the tables in a join. Also, if cost based choices depend upon data values in the query, it should be known that the DataServer typically uses bind variables (to make the SQL more reusable) and ORACLE therefore does not know the values until run time. With deferred execution (on ORACLE's part) this may not make a difference.