```{index} single: AnyDBM_File ``` # AnyDBM_File AnyDBM\_File - provide framework for multiple DBMs NDBM\_File, DB\_File, GDBM\_File, SDBM\_File, ODBM\_File - various DBM implementations ## SYNOPSIS ```perl 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](DB_File.md)), 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: ```perl 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: ```perl use Fcntl; 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: ```text 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](DB_File.md). Requires symbolic links. - \[3\] By default, but can be redefined. ## SEE ALSO dbm(3), ndbm(3), DB\_File(3), [perldbmfilter](https://perldoc.perl.org/perldbmfilter)