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
"function" or "select" methods of either table or
- 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" or
"Alzabo::Create::Schema->sync_backend_sql" methods. 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
- 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