AnyDBM_File(3)							AnyDBM_File(3)

NAME    [Toc]    [Back]

     AnyDBM_File - provide framework for multiple DBMs

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

SYNOPSIS    [Toc]    [Back]

	 use AnyDBM_File;

DESCRIPTION    [Toc]    [Back]

     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
     the DB_File manpage), 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    [Toc]    [Back]

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

			      odbm    ndbm    sdbm    gdbm    bsd-db
			      ----    ----    ----    ----    ------
      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







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AnyDBM_File(3)							AnyDBM_File(3)



     [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 the DB_File manpage. Requires symbolic links.

     [3] By default, but can be	redefined.

SEE ALSO    [Toc]    [Back]

     dbm(3), ndbm(3), DB_File(3)


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