- C-ISAM Buffers

C-ISAM uses buffering by the operating system to reduce the number of disk I/O operations required during execution of function calls. In addition to operating system buffers, C-ISAM maintains its own buffer pool to reduce the number of times it calls the operating system to perform I/O. These internal buffers further reduce overhead during C-ISAM calls. The environment variable ISAMBUFS allows you to specify the number of internal buffers available to C-ISAM.

Generally, allocate four buffers for every index that is in use at any one time, with a minimum of four. The default value for ISAMBUFS is 16.

If you are using a Unix system that uses the Bourne shell, enter the following commands:

ISAMBUFS=xx
export ISAMBUFS

If you are using a Unix system that uses the C shell, enter the following command:

setenv ISAMBUFS xx

If you are using a DOS system, enter the following command:

SET ISAMBUFS=xx

where xx is the number of buffers you wish to allocate (default 16, minimum 4).

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Topic ID: 720026