1AnyDBM_File(3pm)       Perl Programmers Reference Guide       AnyDBM_File(3pm)
2
3
4

NAME

6       AnyDBM_File - provide framework for multiple DBMs
7
8       NDBM_File, DB_File, GDBM_File, SDBM_File, ODBM_File - various DBM
9       implementations
10

SYNOPSIS

12           use AnyDBM_File;
13

DESCRIPTION

15       This module is a "pure virtual base class"--it has nothing of its own.
16       It's just there to inherit from one of the various DBM packages.  It
17       prefers ndbm for compatibility reasons with Perl 4, then Berkeley DB
18       (See DB_File), GDBM, SDBM (which is always there--it comes with Perl),
19       and finally ODBM.   This way old programs that used to use NDBM via
20       dbmopen() can still do so, but new ones can reorder @ISA:
21
22           BEGIN { @AnyDBM_File::ISA = qw(DB_File GDBM_File NDBM_File) }
23           use AnyDBM_File;
24
25       Having multiple DBM implementations makes it trivial to copy database
26       formats:
27
28           use POSIX; use NDBM_File; use DB_File;
29           tie %newhash,  'DB_File', $new_filename, O_CREATâŽȘO_RDWR;
30           tie %oldhash,  'NDBM_File', $old_filename, 1, 0;
31           %newhash = %oldhash;
32
33       DBM Comparisons
34
35       Here's a partial table of features the different packages offer:
36
37                                odbm    ndbm    sdbm    gdbm    bsd-db
38                                ----    ----    ----    ----    ------
39        Linkage comes w/ perl   yes     yes     yes     yes     yes
40        Src comes w/ perl       no      no      yes     no      no
41        Comes w/ many unix os   yes     yes[0]  no      no      no
42        Builds ok on !unix      ?       ?       yes     yes     ?
43        Code Size               ?       ?       small   big     big
44        Database Size           ?       ?       small   big?    ok[1]
45        Speed                   ?       ?       slow    ok      fast
46        FTPable                 no      no      yes     yes     yes
47        Easy to build          N/A     N/A      yes     yes     ok[2]
48        Size limits             1k      4k      1k[3]   none    none
49        Byte-order independent  no      no      no      no      yes
50        Licensing restrictions  ?       ?       no      yes     no
51
52       [0] on mixed universe machines, may be in the bsd compat library, which
53           is often shunned.
54
55       [1] Can be trimmed if you compile for one access method.
56
57       [2] See DB_File.  Requires symbolic links.
58
59       [3] By default, but can be redefined.
60

SEE ALSO

62       dbm(3), ndbm(3), DB_File(3), perldbmfilter
63
64
65
66perl v5.8.8                       2001-09-21                  AnyDBM_File(3pm)
Impressum