Help:Fixed properties 1.8.0
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This page provides information about fixed properties which were introduced to Semantic MediaWiki in version 1.8.0.
The new SQL Store in SMW (SQLStore3) has the new feature called fixed properties. Fixed properties are properties used heavily in a wiki which use a dedicated database table. For example a wiki about people will have a property called "Age" used extensively within the wiki. To optimize operations on this property there is support to have property-value tuples of these properties stored in a separate dedicated database table rather than in the generic table used for their datatypes.
This feature is still experimental and needs some testing. If you are able to produce some performance gain using this feature please refer to it on this page's talk page.
To use this feature you must be using SQLStore3. To use this, you can add a new entry in the
fixedProperties array in the SMWSQLStore3.php file as a key => value pair, where the key is the property name used in the wiki (but with " " replaced with "_" and the first letter capitalized), and the value is the constant used to denote properties of this type in class SMWDataItem, this will be one of the following:
SMWDataItem::TYPE_BLOB // properties of type text and code SMWDataItem::TYPE_URI // properties of type email, telephone number, URL and annotation URI SMWDataItem::TYPE_WIKIPAGE // properties of type page SMWDataItem::TYPE_NUMBER // properties of type number and quantity SMWDataItem::TYPE_TIME // properties of type date SMWDataItem::TYPE_BOOLEAN // properties of type boolean SMWDataItem::TYPE_CONTAINER // properties of type record SMWDataItem::TYPE_GEO // properties of type geographic coordinates
A run of setup using SMWAdmin is needed to create these tables. If an already used property is assigned a new table all old data for this property will become inaccessible for SMW. This can be repaired by either migrating it to the new table or will eventually be updated on page edits.
An example of an entry in the
fixedProperties array would look like
public static $fixedProperties = array( 'Age' => SMWDataItem::TYPE_NUMBER );
where "Age" is a property of type "Number".
Note that this feature is not upgrade proof, i.e. as soon as you replace
SMWSQLStore3.php during each update of you wiki you will have to add your fixed property to the
fixedProperties array again.
This section is proposed to be moved to a separate page within Category:Developer documentation
The name of the database table is formed using md5
$tableName = 'smw_fpt_' . md5( $propertyKey );
- SQLStore update collected notes for the SQLStore3 design
- Database tables collects notes on the Database tables used in SQLStore3
Help:Fixed properties en 1.8.0 1.8.0