anydbm_file(3)
NAME
AnyDBM_File - provide framework for multiple DBMs
NDBM_File, DB_File, GDBM_File, SDBM_File, ODBM_File - var
ious 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_RD- WR;
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 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