Example 3: A single set of files with different processing options

 

You use the same set of files for programs that need read-only file processing and for programs that need some or all of the options (input, update, add, and delete).

The same methods apply if a file is to be processed with certain command parameters in some programs and not in others (for example, sometimes the commit option should be used).

A single Open Database File (OPNDBF) command can be used to specify OPTION(*ALL) and the open data path would be opened shared (if, for example, a previous Override with Database File (OVRDBF) command was used to specify SHARE(*YES)). Each program can then open a subset of the options. The program requests the type of open depending on the specifications in the program. In some cases this does not require any more considerations because a program specifying an open for input only would operate similarly as if it had not done a shared open (for example, no additional record locking occurs when a record is read).

However, some options specified on the OPNDBF command can affect how the program operates. For example, SEQONLY(*NO) is specified on the open command for a file in the program. An error would occur if the OPNDBF command used SEQONLY(*YES) and a program attempted an operation that was not valid with sequential-only processing.

The ACCPTH parameter must also be consistent with the way programs will use the access path (arrival or keyed).

If COMMIT(*YES) is specified on the OPNDBF command and the Start Commitment Control (STRCMTCTL) command specifies LCKLVL(*ALL) or LCKLVL(*CS), any read operation of a record locks that record (per commitment control record locking rules). This can cause records to be locked unexpectedly and cause errors in the program.

Two OPNDBF commands can be used for the same data (for example, one with OPTION(*ALL) and the other specifying OPTION(*INP)). The second use must be a logical file pointing to the same physical file(s). This logical file can then be opened as SHARE(*YES) and multiple uses made of it during the same job.

 

Parent topic:

Close considerations for files shared in a job or an activation group