Database Sequence Numbering

Database sequence numbering provides a method of linking groups of data files so that they and their corresponding log file can be kept in step.

A sequence number, contained in the log file, is automatically stored in the header of each data file for which you have specified sequence numbering. Fileshare increments these sequence numbers every time you invoke the Fileshare Server. In order for the Rollforward Recovery Utility to work, all data files must have sequence numbers that match the log file. If the sequence numbers in the data files do not match, the Fileshare Server fails to start after displaying this message:

FS038-S A matching sequence number not found in <filename>

The possible causes for this error are:

• A data file has been replaced by a file that does not contain the same sequence number as all the other data files listed in the database reference file. To recover, you need to install the correct file(s) on the system.
• A power failure prevented proper shutdown of the Fileshare Server when it was last running. To recover the database files, use rollforward recovery. See the section Rollforward Recovery Utility for further information.

All data files listed in the database reference file have sequence number checking active by default. You can turn off sequence number checking using the database reference file option "/o s" (omit sequence numbering). If sequence number checking is not used on a file, your system administrator must make sure that the correct version of the file is installed in the Fileshare System.

Sequence numbering is only available on data files with a variable length record file header. The following file organizations do not contain headers and so sequence number checking is not possible:

• Line sequential files
• Non-data-compressed fixed length record sequential files
• C-ISAM files
• Non-data-compressed fixed length record relative files

If you have fixed length record data files that you want to use sequence numbering on, create them as variable length record data files. You can do this by changing the file definition in your COBOL program before creating the file.

Example

Data file definition specifying fixed length records:

 FD account-file. 
 01 account-file-record.
    03 account-file-prime pic x(4).

Equivalent data file definition specifying variable length records:

 FD account-file recording mode is variable.
 01 account-file-record.
    03 account-file-prime pic x(4).

You do not have to change the configuration of the Fileshare Client or your program to make use of database sequence numbers.