DBI

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lib/DBD/DBM.pm  view on Meta::CPAN

you to store Perl code or objects in database columns.  When these get
de-serialized, they may be eval'ed - in other words MLDBM (or actually
Data::Dumper when used by MLDBM) may take the values and try to
execute them in Perl.  Obviously, this can present dangers, so if you
do not know what is in a file, be careful before you access it with
MLDBM turned on!

See the entire section on L<Table locking and flock()> for gotchas and
warnings about the use of flock().

=head1 BUGS AND LIMITATIONS

This module uses hash interfaces of two column file databases. While
none of supported SQL engines have support for indices, the following
statements really do the same (even if they mean something completely
different) for each dbm type which lacks C<EXISTS> support:

  $sth->do( "insert into foo values (1, 'hello')" );

  # this statement does ...
  $sth->do( "update foo set v='world' where k=1" );

lib/DBD/File.pm  view on Meta::CPAN

the appropriate absolute path name (based on the current working
directory) when the dbh attribute is set.

  f_dir => "/data/foo/csv",

If C<f_dir> is set to a non-existing location, the connection will fail.
See CVE-2014-10401 for reasoning. Because of this, folders to use cannot
be created after the connection, but must exist before the connection is
initiated.

See L<KNOWN BUGS AND LIMITATIONS>.

=head4 f_dir_search

This optional attribute can be set to pass a list of folders to also
find existing tables. It will B<not> be used to create new files.

  f_dir_search => [ "/data/bar/csv", "/dump/blargh/data" ],

=head4 f_ext

lib/DBD/File.pm  view on Meta::CPAN

table files. Note that not all platforms support locking.  By default,
tables are opened with a shared lock for reading, and with an
exclusive lock for writing. The supported modes are:

  0: No locking at all.

  1: Shared locks will be used.

  2: Exclusive locks will be used.

But see L<KNOWN BUGS|/"KNOWN BUGS AND LIMITATIONS"> below.

=head4 f_lockfile

If you wish to use a lockfile extension other than C<.lck>, simply specify
the C<f_lockfile> attribute:

  $dbh = DBI->connect ("dbi:DBM:f_lockfile=.foo");
  $dbh->{f_lockfile} = ".foo";
  $dbh->{dbm_tables}{qux}{f_lockfile} = ".foo";

lib/DBD/File.pm  view on Meta::CPAN

    # OS                     darwin (12.2.1)
    # Perl                   5.017006 (darwin-thread-multi-ld-2level)

Called in list context, f_versions will return an array containing each
line as single entry.

Some drivers might use the optional (table name) argument and modify
version information related to the table (e.g. DBD::DBM provides storage
backend information for the requested table, when it has a table name).

=head1 KNOWN BUGS AND LIMITATIONS

=over 4

=item *

This module uses flock () internally but flock is not available on all
platforms. On MacOS and Windows 95 there is no locking at all (perhaps
not so important on MacOS and Windows 95, as there is only a single
user).

lib/DBI/SQL/Nano.pm  view on Meta::CPAN

  sub fetch_row ($$$)  { ... }
  sub push_row ($$$)   { ... }
  sub push_names ($$$) { ... }
  sub truncate ($$)    { ... }
  sub seek ($$$$)      { ... }

The base class interfaces are provided by DBI::SQL::Nano::Table_ in case of
relying on DBI::SQL::Nano or SQL::Eval::Table (see L<SQL::Eval> for details)
otherwise.

=head1 BUGS AND LIMITATIONS

There are no known bugs in DBI::SQL::Nano::Statement. If you find a one
and want to report, please see L<DBI> for how to report bugs.

DBI::SQL::Nano::Statement is designed to provide a minimal subset for
executing SQL statements.

The most important limitation might be the restriction on one table per
statement. This implies, that no JOINs are supported and there cannot be
any foreign key relation between tables.