Kbase P115072: SQL: Is it true that the SQL engine will use only one index where the 4GL engine would use multiple
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
12/8/2008 |
|
Status: Verified
GOAL:
SQL: Is it true that the SQL engine will use only one index where the 4GL engine would use multiple indexes for an equivalent query?
GOAL:
Can the SQL engine use multiple indexes in query resolution?
GOAL:
Does the SQL engine use multiple indexes to resolve an SQL query?
FACT(s) (Environment):
All Supported Operating Systems
Progress 9.1x
OpenEdge 10.x
FIX:
It is possible that an SQL query will use one index only to resolve a query where the 4GL/ABL engine would use multiple indexes to resolve an equivalent query. The OpenEdge SQL engine can and does use multiple indexes for a query but it does not do so as aggressively as the 4GL.
The OpenEdge SQL engine may use 2 or more indexes, depending on the estimated cost, when a query contains predicates that apply to multiple indexes, and those predicates are OR'd together. For example:
SELECT * FROM PUB.Customer WHERE CustNum = 123 OR Zip = 98765;