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"
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>