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.\"
.IX Title "Alzabo::MySQL 3pm"
.TH Alzabo::MySQL 3pm "2022-06-14" "perl v5.34.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Alzabo::MySQL \- Alzabo and MySQL
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This documentation is about what special support Alzabo has for MySQL,
as well as what is lacking.
.PP
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.
.SS "Indexes"
.IX Subsection "Indexes"
.IP "\(bu" 4
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.
.IP "\(bu" 4
Alzabo supports the creation of fulltext indexes and their use in
\&\s-1SELECT\s0 and \s-1WHERE\s0 clauses.  This includes the ability to get back the
score given for a match as part of a select, using the \f(CW\*(C`function\*(C'\fR or
\&\f(CW\*(C`select\*(C'\fR methods of either table or schema objects.
.SS "Reverse Engineering"
.IX Subsection "Reverse Engineering"
.IP "\(bu" 4
When reverse engineering a schema, Alzabo knows that MySQL has
\&\*(L"default defaults\*(R" for certain column types.  For example, if a \s-1DATE\s0
column is specified as \s-1NOT NULL\s0 but is not assigned a default, MySQL
gives this column a default of '0000\-00\-00'.
.Sp
Because Alzabo knows about this, it will ignore these defaults when
reverse engineering an \s-1RDBMS.\s0
.IP "\(bu" 4
Similarly, Alzabo knows that MySQL assigns default \*(L"lengths\*(R" to many
column types.  For example, if given \s-1INTEGER\s0 as a column type, MySQL
will convert this to \s-1INTEGER\s0(11) or \s-1INTEGER\s0(10), depending on the
version of MySQL being used.
.Sp
Again, Alzabo ignores these lengths when reverse engineering a schema.
.IP "\(bu" 4
All of this may lead to apparent inconsistencies when using the with
the \f(CW\*(C`Alzabo::Create::Schema\->sync_backend\*(C'\fR or \f(CW\*(C`Alzabo::Create::Schema\->sync_backend_sql\*(C'\fR methods.  If you are
using this feature from the web based schema creator, you will see
that even immediately after running the \f(CW\*(C`sync_backend()\*(C'\fR method,
Alzabo may still think there are differences between the two schemas.
This is not a problem, as running the \s-1SQL\s0 Alzabo generates will not
actually change your database.
.SS "Transactions"
.IX Subsection "Transactions"
.RS 4
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 \s-1DBI\s0's
\&\f(CW\*(C`begin_work()\*(C'\fR method, whether or not this will actually do anything.
.RE
.SS "Constraints and Foreign Keys"
.IX Subsection "Constraints and Foreign Keys"
.IP "\(bu" 4
Column constraints are treated as column attributes.
.IP "\(bu" 4
Foreign key constraints are not generated when generating \s-1SQL\s0 for a
MySQL schema.  This will probably change in the future.
.SS "Table Types"
.IX Subsection "Table Types"
.RS 4
These can be specified as a table attribute.
.RE