3.3.11 Converting C-ISAM Files

vutil can convert a C-ISAM® file into a Vision file. This is useful when you are moving C-ISAM data to an ACUCOBOL-GT application. The command is:

vutil  -convert  [ -a ]  [ +c ]  [ -234 ]  [ -d dir ]
  [ -f # ]  [ -q ]  [ files ]

You need not specify that the file is C-ISAM; vutil will determine that.

Note that the "convert" option starts with the same letter as the "check" option described earlier. You must use at least two letters of the word "convert" in order to specify this option. If you just use "-c", vutil will assume that you are specifying the "check" option.

The "convert" function will take each named file and convert it from a C-ISAM file to a corresponding Vision file. If no files are specified, then the standard input is read for a list of files to convert.

Note that each C-ISAM file actually occupies two files: an index file with the extension ".idx" and a data file with the extension ".dat". Specify only the base file name in the list of files.

Specifying "+c" will cause the resulting records to be compressed.

Normally vutil will warn the user about the impending conversion and ask if he or she wants to continue. The "-a" (for "automatic") option suppresses this warning. This can be useful when you are calling vutil from another program.

The "-4" option specifies that you want the resulting file to be in Vision Version 4. A "-3" means you want the file to be a Version 3 file, and "-2" means you want a Version 2 file.

The "-d" option specifies that you want the converted files to be placed in a new directory. Dir should be the name of a directory on the machine other than the directory containing the files to be converted. The "-d" option implies the "-a" option.

The "-f #" option sets the compression factor to be used when the file is converted. This option does not force the use of compression, it merely sets the compression factor if compression is used. The compression factor, a numeric literal, specifies how much of the space saved by compression is actually to be removed from the record.

The "-q" option causes vutil to exit (with status 99) if user interaction is required.

There are a few types of files that cannot be converted due to restrictions in Vision. Any of the following properties will cause vutil to print a message and leave the file alone:

1. A record size or block size greater than 32 KB.

2. More than 120 keys.

3. An individual key with more than 250 bytes in it.

4. A single key with more than sixteen segments (Vision Version 4) or more than six segments (Vision Version 2 or 3).

5. A primary key that allows duplicates.

Note that vutil must make a copy of the file while it is converting it. You must have adequate disk space for vutil to complete its conversion. Also note that C-ISAM files and Vision files differ in the amount of disk space that they use. This difference is fairly unpredictable and can vary quite widely. Sometimes the Vision files are smaller, and sometimes the C-ISAM files are smaller. You should have some spare disk space when you start converting files to accommodate the potential difference.