A perl utility for scanning two MySQL database schemas and generating a diff between them. The result will be the necessary SQL for transforming the first database schema into the second.

The script will also make judgements about the relative safety of the operations.

• Adding a table
• Adding a column
• Column type change that would cause no data loss (e.g. INT -> BIGINT, UINT -> INT, VARCHAR -> TEXT, INT -> VARCHAR, INT -> FLOAT, ...)
• Changing NOT NULL to NULL
• Adding an UNIQUE, FULLTEXT, or standard INDEX to a column

• Removing a table
• Changing table storage engine
• Changing character set/collation
• Column removal
• Column rename
• Addition/removal of auto_increment on a column
• Changing NULL to NOT NULL
• Changing primary key
• Changing default value
• Column type change that may lose data
• Index removal
  • NOTE: DEFAULT CURRENT_TIMESTAMP, ON UPDATE CURRENT_TIMESTAMP, and auto_increment columns must be indexed. Beware multi-column indexes.

• Change of index type (BTREE/RTREE/HASH)
• Change of table AUTO_INCREMENT value

• Allow database schemas to be read from database hosts directly rather than from dump files.
• Interpret statements other than USE/CREATE DATABASE/CREATE TABLE/DROP TABLE
• Detecting "safe" character set/collation changes
• Detecting "safe" shrinking of column type
• Combine SQL deltas to form a single delta
• Combine 1+ deltas with a base schema to form an updated base schema