Help:Configuration parameter "$smwgQueryResultNonEmbeddedCacheLifetime"

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Title $smwgQueryResultNonEmbeddedCacheLifetime
Description Sets the cache lifetime of non-embedded queries and their results fetched from the query engine
Default setting
60 * 10
Software Semantic MediaWiki
First version supported
Last version supported still available
Configuration Cache
Keyword caching · performance · query performance · browsing interface

$smwgQueryResultNonEmbeddedCacheLifetime is a configuration parameter that sets the cache lifetime of non-embedded queries and their results, e.g. browsing interfaces such as special page "Ask", etc. or the API fetched from the query engine. It was introduced in Semantic MediaWiki 2.5.0.12

NoteNote: This setting only takes effect if the query results cache was enabled.

Default setting

$smwgQueryResultNonEmbeddedCacheLifetime = 60 * 10;

This means that by default lifetime of the query result cache is ten minutes.

Changing the default setting

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

Disable the caching for non-embedded queries
$smwgQueryResultCacheLifetime = 0;

or

$smwgQueryResultCacheLifetime = false;
Extend the cache lifetime to an hour
$smwgQueryResultCacheLifetime = 60 * 60;

General notes

  • This setting can also be used to minimize a possible Denial-of-service attacks by preventing an advisory to make unlimited query requests from either special page "Ask" or the API that may lock the database due to complex query answering and instead being rerouted to the cache once a result has been computed.
  • Non-embedded queries cannot not be tracked using embedded query updates since the subject is being missing that would identify the entity. Therefore an auto-purge mechanism as in case of an embedded entity is not possible hence the lifetime should be carefully selected to provide the necessary means for a user and the application.

See also