Help:$smwgSparqlDefaultGraph

is a configuration parameter that is used to set the identifier (graph) of the the semantic update store when using a SPARQL database. The parameter was introduced in.

Default setting
This means that no name for the default graph was defined. Leaving the default graph URI empty only works if the SPARQL store is configured to use some default default graph or if it generally supports this.

Changing the default setting
To modify the setting to this configuration parameter, add one of the following lines to your "LocalSettings.php" file after the  call:

The default graph is similar to a database name in relational databases. It can be set to any URI, e.g. the main page URI of your wiki with "#graph" appended. Different wikis should normally use different default graphs unless there is a good reason to share one graph. Moreover, once set this name should not be changed even in case of an URL change since it serves as an unique universal identifier.
 * Defining a default name for the graph