Author: jzucker
Date: Sat Mar 6 16:19:33 2004
New Revision: 199
Modified:
dbi/trunk/lib/DBD/DBM.pm
Log:
pod addition for BerkeleyDB
Modified: dbi/trunk/lib/DBD/DBM.pm
==============================================================================
--- dbi/trunk/lib/DBD/DBM.pm (original)
+++ dbi/trunk/lib/DBD/DBM.pm Sat Mar 6 16:19:33 2004
@@ -89,8 +89,7 @@
, dbm_version => 1 # verbose DBD::DBM version
, dbm_ext => 1 # file extension
, dbm_store_metadata => 1 # column names, etc.
- , dbm_rdonly => 1 # for Berkeley DB
- , dbm_create => 1 # for Berkeley DB
+ , dbm_berkeley_flags => 1 # for BerkeleyDB
};
my($var, $val);
@@ -352,18 +351,29 @@
# TIEING
#
+ # allow users to pass in a pre-created tied object
+ #
if ($dbm_type eq 'BerkeleyDB') {
- my $DB_CREATE = 1; # DB_CREATE should import constants
- my $DB_RDONLY = 16; # DB_RDONLY should import constants
- my %flags = ( '-Flags' => $DB_RDONLY );
- %flags = ( '-Flags' => $DB_CREATE ) if $lockMode or $createMode;
- my $t = 'BerkeleyDB::Hash';
- $t = 'MLDBM' if $serializer;
- if ( $self->{command} ne 'DROP') {
- eval { tie %h, $t, -Filename=>$file, %flags }
+ my $DB_CREATE = 1; # but import constants if supplied
+ my $DB_RDONLY = 16; #
+ my %flags;
+ if (my $f = $dbh->{dbm_berkeley_flags}) {
+ $DB_CREATE = $f->{DB_CREATE} if $f->{DB_CREATE};
+ $DB_RDONLY = $f->{DB_RDONLY} if $f->{DB_RDONLY};
+ delete $f->{DB_CREATE};
+ delete $f->{DB_RDONLY};
+ %flags = %$f;
}
+ $flags{'-Flags'} = $DB_RDONLY;
+ $flags{'-Flags'} = $DB_CREATE if $lockMode or $createMode;
+ my $t = 'BerkeleyDB::Hash';
+ $t = 'MLDBM' if $serializer;
+ if ( $self->{command} ne 'DROP') {
+ eval { tie %h, $t, -Filename=>$file, %flags }
+ }
+ # warn $BerkeleyDB::db_version;
}
- else {
+ elsif (!%h) {
eval { tie(%h, $tie_type, $file, $open_mode, 0666) }
unless $self->{command} eq 'DROP';
}
@@ -823,6 +833,30 @@
See below for some L<Gotchas and Warnings> about MLDBM.
+=head2 Support for Berkeley DB
+
+The Berkeley DB storage type is supported through two different Perl modules -
DB_File (which supports only features in old versions of Berkeley DB) and BerkeleyDB
(which supports all versions). DBD::DBM supports specifying either "DB_File" or
"BerkeleyDB" as a I<dbm_type>, with or without MLDBM support.
+
+The "BerkeleyDB" dbm_type is experimental and its interface is likely to chagne. It
currently defaults to BerkeleyDB::Hash and does not currently support ::Btree or
::Recno.
+
+With BerkeleyDB, you can specify initialization flags by setting them in your script
like this:
+
+ my $dbh = DBI->connect('dbi:DBM:type=BerkeleyDB;mldbm=S');
+ use BerkeleyDB;
+ my $env = new BerkeleyDB::Env -Home => $dir; # and/or other Env flags
+ $dbh->{dbm_berkeley_flags} = {
+ 'DB_CREATE' => DB_CREATE # pass in constants
+ , 'DB_RDONLY' => DB_RDONLY # pass in constants
+ , '-Cachesize' => 1000 # set a ::Hash flag
+ , '-Env' => $env # pass in an environment
+ };
+
+Do I<not> set the -Flags or -Filename flags, those are determined by the SQL (e.g.
-Flags => DB_RDONLY is set automatically when you issue a SELECT statement).
+
+Time has not permitted me to provide support in this release of DBD::DBM for further
Berkeley DB features such as transactions, concurrency, locking, etc. I will be
working on these in the future and would value suggestions, patches, etc.
+
+See L<DB_File> and L<BerkeleyDB> for further details.
+
=head2 Supported SQL syntax
DBD::DBM uses a subset of SQL. The robustness of that subset depends on what other
modules you have installed. Both options support basic SQL operations including CREATE
TABLE, DROP TABLE, INSERT, DELETE, UPDATE, and SELECT.
