Alzabo::MySQL - Alzabo and MySQL
This documentation is about what special support Alzabo has for MySQL, as well as what is lacking.
MySQL support is based on the 3.23.* release series, with some support for features that are starting to appear in the 4.0.* releases. Earlier versions of MySQL will probably work with Alzabo, though Alzabo cannot magically make these releases support new features like fulltext indexes.
Alzabo supports the ability to specify prefixes when adding an index. Prefixes are required when attempting to index any sort of text or blob column.
Alzabo supports the creation of fulltext indexes and their use in SELECT and WHERE clauses. This includes the ability to get back the score given for a match as part of a select, using the
selectmethods of either table or schema objects.
When reverse engineering a schema, Alzabo knows that MySQL has "default defaults" for certain column types. For example, if a DATE column is specified as NOT NULL but is not assigned a default, MySQL gives this column a default of '0000-00-00'.
Because Alzabo knows about this, it will ignore these defaults when reverse engineering an RDBMS.
Similarly, Alzabo knows that MySQL assigns default "lengths" to many column types. For example, if given INTEGER as a column type, MySQL will convert this to INTEGER(11) or INTEGER(10), depending on the version of MySQL being used.
Again, Alzabo ignores these lengths when reverse engineering a schema.
All of this may lead to apparent inconsistencies when using the with the
Alzabo::Create::Schema->sync_backend_sqlmethods. If you are using this feature from the web based schema creator, you will see that even immediately after running the
sync_backend()method, Alzabo may still think there are differences between the two schemas. This is not a problem, as running the SQL Alzabo generates will not actually change your database.
Alzabo will try to use transactions whenever appropriate. Unfortunately, there is no way to determine whether or not a given table supports transactions so Alzabo simply calls DBI's
begin_work() method, whether or not this will actually do anything.
Constraints and Foreign Keys
Column constraints are treated as column attributes.
Foreign key constraints are not generated when generating SQL for a MySQL schema. This will probably change in the future.
These can be specified as a table attribute.