AnyDBM_File(3) Perl Programmers Reference Guide AnyDBM_File(3) NNNNAAAAMMMMEEEE AnyDBM_File - provide framework for multiple DBMs NDBM_File, DB_File, GDBM_File, SDBM_File, ODBM_File - various DBM implementations SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS use AnyDBM_File; DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN 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 _D_B___F_i_l_e manpage), GDBM, SDBM (which is always there--it comes with Perl), and finally ODBM. This way old programs that used to use NDBM via _d_b_m_o_p_e_n_(_) 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; DDDDBBBBMMMM CCCCoooommmmppppaaaarrrriiiissssoooonnnnssss 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 12/Jul/1999 perl 5.005, patch 03 1 AnyDBM_File(3) Perl Programmers Reference Guide 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 _D_B___F_i_l_e manpage. Requires symbolic links. [3] By default, but can be redefined. SSSSEEEEEEEE AAAALLLLSSSSOOOO _d_b_m(3), _n_d_b_m(3), _D_B___F_i_l_e(3) 12/Jul/1999 perl 5.005, patch 03 2