This seems to be a useful tool to convert mysql or oracle schema to redshift. select queries can also be migrated easily using...

www.sqlines.com

$ # As of March 2009, the latest version was 3.6.11.
$ wget www.sqlite.org
$ tar xzf sqlite-amalgamation-3.6.11.tar.gz
$ cd sqlite-3.6.11
$ ./configure && make
$ sudo make install

When there is maintenance work to be carried on the database server, you can simply skip networking so that no connection from any other server from the network will be accepted.
Simply enter the following in /etc/my.cnf:

[mysqld]

Prevent network access to MySQL.

skip-networking

mysql -e"SELECT CONCAT('OPTIMIZE TABLES ', GROUP_CONCAT(TABLE_SCHEMA, '.', TABLE_NAME ORDER BY TABLE_SCHEMA, TABLE_NAME SEPARATOR ',')) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'dbname' GROUP BY TABLE_SCHEMA\G
" | awk -F: '{print $2}' | mysql