NAME

       Alzabo::Create::Index - Index objects for schema creation

SYNOPSIS

         use Alzabo::Create::Index;

DESCRIPTION

       This object represents an index on a table.  Indexes consist of columns and optional
       prefixes for each column.  The prefix specifies how many characters of the columns should
       be indexes (the first X chars).  Some RDBMS's do not have a concept of index prefixes.
       Not all column types are likely to allow prefixes though this depends on the RDBMS.  The
       order of the columns is significant.

INHERITS FROM

       "Alzabo::Index"

       Note: all relevant documentation from the superclass has been merged into this document.

METHODS

   new
       The constructor takes the following parameters:

       •   table => "Alzabo::Create::Table" object

           The table that this index is indexing.

       •   columns => [ "Alzabo::Create::Column" object, .. ]

       •   columns => [ { column => "Alzabo::Create::Column" object,
                                  prefix => $prefix },
                                 repeat as needed ...
                              ]

           This parameter indicates which columns that are being indexed.  It can either be an
           array reference of column objects, or an array reference of hash references, each with
           a key called column and one called prefix.

           The prefix key is optional.

       •   unique => $boolean

           Indicates whether or not this is a unique index.

       •   fulltext => $boolean

           Indicates whether or not this is a fulltext index.

       •   function => $string

           This can be used to create a function index where supported. The value of this
           parameter should be the full function, with column names, such as "LCASE( username )".

           The "columns" parameter should include all the columns used in the function.

       Returns a new "Alzabo::Create::Index" object.

       Throws: "Alzabo::Exception::Params", "Alzabo::Exception::RDBMSRules"

   table
       Returns the "Alzabo::Create::Table" object to which the index belongs.

   columns
       Returns an ordered list of the "Alzabo::Create::Column" objects that are being indexed.

   add_column
       Adds a column to the index.

       This method takes the following parameters:

       •   column => "Alzabo::Create::Column" object

       •   prefix => $prefix (optional)

       Throws: "Alzabo::Exception::Params", "Alzabo::Exception::RDBMSRules"

   delete_column ("Alzabo::Create::Column" object)
       Deletes the given column from the index.

       Throws: "Alzabo::Exception::Params", "Alzabo::Exception::RDBMSRules"

   prefix ("Alzabo::Create::Column" object)
       A column prefix is, to the best of my knowledge, a MySQL specific concept, and as such
       cannot be set when using an RDBMSRules module for a different RDBMS.  However, it is
       important enough for MySQL to have the functionality be present.  It allows you to specify
       that the index should only look at a certain portion of a field (the first N characters).
       This prefix is required to index any sort of BLOB column in MySQL.

       This method returns the prefix for the column in the index.  If there is no prefix for
       this column in the index, then it returns undef.

   set_prefix
       This method takes the following parameters:

       •   column => "Alzabo::Create::Column" object

       •   prefix => $prefix

       Throws: "Alzabo::Exception::Params", "Alzabo::Exception::RDBMSRules"

   unique
       Returns a boolean value indicating whether the index is a unique index.

   set_unique ($boolean)
       Sets whether or not the index is a unique index.

   fulltext
       Returns a boolean value indicating whether the index is a fulltext index.

   set_fulltext ($boolean)
       Set whether or not the index is a fulltext index.

       Throws: "Alzabo::Exception::Params", "Alzabo::Exception::RDBMSRules"

   register_column_name_change
       This method takes the following parameters:

       •   column => "Alzabo::Create::Column" object

           The column (with the new name already set).

       •   old_name => $old_name

       This method is called by the table object which owns the index when a column name changes.
       You should never need to call this yourself.

       Throws: "Alzabo::Exception::Params"

   id
       The id is generated from the table, column and prefix information for the index.  This is
       useful as a canonical name for a hash key, for example.

       Returns a string that is the id which uniquely identifies the index in this schema.

AUTHOR

       Dave Rolsky, <autarch@urth.org>