1.4. Multiple Database Tables

Interchange can manage an unlimited number of arbitrary database tables. They use the TAB delimiter by default, but several flexible delimiter schemes are available. These are defined by default:

   Type 1      DEFAULT - uses default TAB delimiter
   Type 2      LINE
               Each field on its own line, a blank line
               separates the record. Watch those carriage
               returns! Also has a special format when CONTINUE
               is set to be NOTES.
   Type 3      %%
               Fields separated by a \n%%\n combination, records by
               \n%%%\n (where \n is a newline). Watch those carriage
   Type 4      CSV
   Type 5      PIPE
   Type 6      TAB
   Type 7      reserved
   Type 8      SQL
   Type 9      LDAP

The databases are specified in Database directives, as:

   Database    arbitrary arbitrary.csv CSV

This specifies a Type 4 database, the ASCII version of which is located in the file arbitrary.csv, and the identifier it will be accessed under in Interchange is "arbitrary." The DBM file, if any, will be created in the same directory if the ASCII file is newer, or if the DBM file does not exist. The files will be created as arbitrary.db or arbitrary.gdbm, depending on DBM type.

The identifier is case sensitive, and can only contain characters in the class [A-Za-z0-9_]. Fields are accessed with the [item_data identifier field] or [data identifier field key] elements. NOTE: Use of lower-case letters is strongly recommended.

If one of the first six types is specified, the database will automatically be built in the default Interchange DB style. The type can be specified with DB_FILE, GDBM, or MEMORY, if the type varies from that default. They will coexist with an unlimited number of DBI databases of different types.

In addition to the database, the session files will be kept in the default format, and are affected by the following actions.

The order of preference is:


            perl -e 'require GDBM_File and print "I have GDBM.\n"'

DB_File (Berkeley DB)

            perl -e 'require DB_File and print "I have Berkeley DB.\n"'
            # csh or tcsh
            setenv MINIVEND_DBFILE 1
            # sh, bash, or ksh
            Database arbitrary  DB_FILE  1


            Database arbitrary  MEMORY  1

Note: The use of memory databases is not recommended.