Two Response Buffers
Usage Notes
The Two Response Buffers field specifies whether or not double-buffering is to be used for the response.
Language |
Variable Name |
COBOL: |
DBCAREA-TWO-RESP-BUFS |
C: DBCAREA.H: |
two_resp_bufs |
Routine |
Action Taken |
DBCHINI: |
writes |
DBCHCL: |
reads (CON; RSUP: IRQ) |
Used by |
Action Taken |
application program |
writes |
Two Response Buffers is initialized by DBCHINI to the default value provided for Two Response Buffers in the site’s SPB.
If the value provided is not appropriate for the application, before calling DBCHCL for the Connect, Run Startup, or Initiate Request function, the application program may set:
Double buffering is useful when large responses are expected from the Teradata Database and large response buffers are used. Substantial improvements in response time can result by transferring the next buffer-full of response data from the Teradata Database while the previous buffer-full is being accessed by the application program.
The response buffer or buffers are re-stocked automatically by DBCHCL. The application program may have to wait for data to arrive if the application program is consuming the data faster than the Teradata Database can re-stock the buffer, but it does not have to arrange for data to arrive.
Note: The connect request’s response is not double-buffered, even if Two Response Buffers is set to Y when DBCHCL is called for the Connect function. However, any other request’s responses on that session are double buffered, unless the setting of Two Response Buffers is changed before the request is submitted.
Although the value of Two Response Buffers is read and stored by the Connect function, it is not used for the connect operation itself.
Two Response buffers will be ignored if the fetch request is for LOB or cursor repositioning responses.