NAME

       mysql-schema-diff - compare MySQL database schemas

SYNOPSIS

         mysql-schema-diff [B<options>] B<database1> B<database2>

         mysql-schema-diff --help

DESCRIPTION

       mysql-schema-diff is a Perl script front-end to the CPAN <http://www.perl.com/CPAN> module
       MySQL::Diff <http://search.cpan.org/search?module=MySQL::Diff> which compares the data
       structures (i.e. schema / table definitions) of two MySQL <http://www.mysql.com/>
       databases, and returns the differences as a sequence of MySQL commands suitable for piping
       into mysql which will transform the structure of the first database to be identical to
       that of the second (c.f. diff and patch).

       Database structures can be compared whether they are files containing table definitions or
       existing databases, local or remote.

       N.B. The program makes no attempt to compare any of the data which may be stored in the
       databases.  It is purely for comparing the table definitions.  I have no plans to
       implement data comparison; it is a complex problem and I have no need of such
       functionality anyway.  However there is another program coldiff
       <http://rossbeyer.net/software/mysql_coldiff/> which does this, and is based on an older
       program called datadiff which seems to have vanished off the 'net.

       For PostgreSQL there are similar tools such as pgdiff <http://pgdiff.sourceforge.net/> and
       apgdiff <http://apgdiff.startnet.biz/>.

EXAMPLES

         # compare table definitions in two files
         mysql-schema-diff db1.mysql db2.mysql

         # compare table definitions in a file 'db1.mysql' with a database 'db2'
         mysql-schema-diff db1.mysql db2

         # interactively upgrade schema of database 'db1' to be like the
         # schema described in the file 'db2.mysql'
         mysql-schema-diff -A db1 db2.mysql

         # compare table definitions in two databases on a remote machine
         mysql-schema-diff --host=remote.host.com --user=myaccount db1 db2

         # compare table definitions in a local database 'foo' with a
         # database 'bar' on a remote machine, when a file foo already
         # exists in the current directory
         mysql-schema-diff --host2=remote.host.com --password=secret db:foo bar

OPTIONS

       More details to come; for now run "mysql-schema-diff --help".

INTERNALS

       For both of the database structures being compared, the following happens:

       •   If the argument is a valid filename, the file is used to create a temporary database
           which "mysqldump -d" is run on to obtain the table definitions in canonicalised form.
           The temporary database is then dropped.  (The temporary database is named
           "test_mysqldiff_temp_something" because default MySQL permissions allow anyone to
           create databases beginning with the prefix "test_".)

       •   If the argument is a database, "mysqldump -d" is run directly on it.

       •   Where authentication is required, the hostname, username, and password given by the
           corresponding options are used (type "mysql-schema-diff --help" for more information).

       •   Each set of table definitions is now parsed into tables, and fields and index keys
           within those tables; these are compared, and the differences outputted in the form of
           MySQL statements.

BUGS, DEVELOPMENT, CONTRIBUTING

       See <http://software.adamspiers.org/wiki/mysqldiff>.

COPYRIGHT AND LICENSE

       Copyright (c) 2000-2011 Adam Spiers. All rights reserved. This program is free software;
       you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

       MySQL::Diff, MySQL::Diff::Database, MySQL::Diff::Table, MySQL::Diff::Utils, mysql,
       mysqldump, mysqlshow

AUTHOR

       Adam Spiers <mysqldiff@adamspiers.org>