Help:Con­figu­ration para­meter "$smwgExperimentalFeatures"

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Configuration parameter details:
Title	$smwgExperimentalFeatures
Description	Sets experimental features
Default setting	SMW_SQLSTORE_TRAVERSAL_PROPERTY_LOOKUP
Software	Semantic MediaWiki
Since version	3.0.0
Until version	still available
Configuration	Query performance · Store settings · Miscellaneous
Keyword	query features · query performance · store setup · store · mysql · postgresql

$smwgExperimentalFeatures is a configuration parameter to enable features 12 that are considered stable but for any unforeseen behaviour, the feature can be disabled to return to a previous working state avoiding the need for hot-patching a system. The configuration parameter was introduced in Semantic MediaWiki 3.0.0Released on an unknown date and compatible with MW 1.27.0 - 1.30.x..

Due to the added indices introduced by the improved entity lookup specific features, the maintenance script setupStore.phpAllows to set up the data backend/store or MediaWiki's maintenance script "update.php" might take longer to run the first time depending largely on the size of the database backend.

Default setting

$smwgExperimentalFeatures = SMW_SQLSTORE_TRAVERSAL_PROPERTY_LOOKUP;

This means that improved entity lookup specific features are used addressing the "Store::getInProperties" performance triggering a significant improvement in query execution time by extending the "INNER JOIN "with a subquery to pre-select and filter possible matches before being materialized.

Available options

• SMW_SQLSTORE_TRAVERSAL_PROPERTY_LOOKUP – Sets that a new query form for selecting incoming properties is being used, this flag1 It is specific to relational data stores, i.e. MySQL and PostgreSQL.

Changing the default setting

If you change the setting for this configuration parameter, please ensure to run maintenance script setupStore.phpAllows to set up the data backend/store followed by maintenance script rebuildData.phpAllows to rebuild all the semantic data for a selected data backend/store.

To modify this configuration setting, add one of the following lines to your "LocalSettings.php" file after the enableSemantics() call:

Disable entity specific lookup features

$smwgExperimentalFeatures = '';

or alternatively

$smwgExperimentalFeatures = false;

  Note: Currently this is equal to disabling all experimental features which will in future no be recommended in case this configuration parameters offers more than just one feature flag.

This setting allows to retain the behaviour prior to the introduction of the new behavior in connection with the respective new feature in the unlikely case that issues arise.

References

1. a b ↑ Semantic MediaWiki: GitHub pull request gh:smw:2461
2. ^ ↑ Semantic MediaWiki: GitHub pull request gh:smw:2936