Kbase 21095: Row Retrieval Process Explained
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
16/12/2004 |
|
Status: Verified
GOAL:
Row Retrieval process and how Progress can retrieve records explained.
GOAL:
How does Progress retrieve records?
GOAL:
Row Retrieval process Explained?
FACT(s) (Environment):
Progress 9.x
OpenEdge 10
FIX:
To retrieve rows, Progress first uses the index brackets. The client opens a new index cursor or uses an already open one. It then sends the server a request that includes the cursor identifier and the bracket range, which are the low-key and high-key values, and asks for the next, previous, first or last rows in the bracket.
Once a row is retrieved using the index brackets, further selection process continues by applying any remaining selection conditions specified in the WHERE clause.
It is important to note that there are some selection operations that the server can not do, either because they require access to program variables on the client side, or because they are not implemented on the server side, such as CAN-FIND. In such cases the server will send the rows in the bracket to the client and the client will apply the remaining selection conditions.