Enabling block fetch
Using block fetch improves performance of certain types of SQL queries by asynchronously pre-extracting rows (on the server node) ahead of the current row. The pre-extracted rows are then sent back to the requesting node in blocks that contain multiple rows of data.
Procedure
To enable block fetch, use the
MODIFY PARM command to add the following parameter to the CQDSIN00 configuration member:
“MODIFY PARM NAME(PREFETCH) VALUE(3 BLOCKS)”| Parameter | Description | Valid values |
|---|---|---|
| PREFETCH | Controls how many blocks of rows should be fetched from
DB2. These blocks of rows are used to build the compressed row buffers
that are sent to an ODBC application from the server. This value should
only be changed if the buffers that are being transmitted from the
server to an ODBC client application are not full.
Note: This parameter
value should be changed only when recommended by technical support.
|
3 (default) |