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AnyDBM_File(3pm)                      Perl Programmers Reference Guide                      AnyDBM_File(3pm)



NAME
       AnyDBM_File - provide framework for multiple DBMs

       NDBM_File, DB_File, GDBM_File, SDBM_File, ODBM_File - various DBM implementations

SYNOPSIS
           use AnyDBM_File;

DESCRIPTION
       This module is a "pure virtual base class"--it has nothing of its own.  It's just there to inherit
       from one of the various DBM packages.  It prefers ndbm for compatibility reasons with Perl 4, then
       Berkeley DB (See DB_File), GDBM, SDBM (which is always there--it comes with Perl), and finally ODBM.
       This way old programs that used to use NDBM via dbmopen() can still do so, but new ones can reorder
       @ISA:

           BEGIN { @AnyDBM_File::ISA = qw(DB_File GDBM_File NDBM_File) }
           use AnyDBM_File;

       Having multiple DBM implementations makes it trivial to copy database formats:

           use POSIX; use NDBM_File; use DB_File;
           tie %newhash,  'DB_File', $new_filename, O_CREAT|O_RDWR;
           tie %oldhash,  'NDBM_File', $old_filename, 1, 0;
           %newhash = %oldhash;

       DBM Comparisons

       Here's a partial table of features the different packages offer:

                                odbm    ndbm    sdbm    gdbm    bsd-db
                                ----    ----    ----    ----    ------Linkage -----Linkage
        Linkage comes w/ perl   yes     yes     yes     yes     yes
        Src comes w/ perl       no      no      yes     no      no
        Comes w/ many unix os   yes     yes[0]  no      no      no
        Builds ok on !unix      ?       ?       yes     yes     ?
        Code Size               ?       ?       small   big     big
        Database Size           ?       ?       small   big?    ok[1]
        Speed                   ?       ?       slow    ok      fast
        FTPable                 no      no      yes     yes     yes
        Easy to build          N/A     N/A      yes     yes     ok[2]
        Size limits             1k      4k      1k[3]   none    none
        Byte-order independent  no      no      no      no      yes
        Licensing restrictions  ?       ?       no      yes     no

       [0] on mixed universe machines, may be in the bsd compat library, which is often shunned.

       [1] Can be trimmed if you compile for one access method.

       [2] See DB_File.  Requires symbolic links.

       [3] By default, but can be redefined.

SEE ALSO
       dbm(3), ndbm(3), DB_File(3), perldbmfilter



perl v5.8.8                                      2001-09-21                                 AnyDBM_File(3pm)