09-16-2010
Quote:
Originally Posted by
STOIE
@ NEO
I am sure I could do that, but really wanted to package it neatly into a query.
Programming is being done in PERL
Hi Stoie,
I understand completely!
IMHO, the query is 'neater' if smaller and you simply read into an array and use PERL to organize and extract the data you need.
Of course, you can program anyway you like!
I can tell you, from experience with a busy forum driven by PHP and MySQL, that complex MySQL queries cause performance (slow query) problems, are hard to debug, and generally do not perform well. Here, where we do millions and millions of MySQL queries a day, the only queries that cause problems (slow queries) are those written by programmers who embed the logic in the actual query and not in the PHP processing. Based on years of experience with MySQL in these forums, I like simple queries and logic in actual code... just me of course.
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LEARN ABOUT DEBIAN
mysql-schema-diff
MYSQLDIFF(1p) User Contributed Perl Documentation MYSQLDIFF(1p)
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:
o 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_".)
o If the argument is a database, "mysqldump -d" is run directly on it.
o Where authentication is required, the hostname, username, and password given by the corresponding options are used (type
"mysql-schema-diff --help" for more information).
o 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>
perl v5.14.2 2012-04-06 MYSQLDIFF(1p)