Help:Deferred updates

introduces CiteRef::gh:smw:1435 to conform with MediaWiki's Phabricator task "T92357"CiteRef::phab:mw:T92357 which together with  is responsible that most updates are being pushed into the deferred update queue provided by MediaWiki's   class to avoid racing conditions and conflicts with the   and   processes.

are executed during the  at a point of "... at the end of the request, either before or after the HTTP response has been sent. In either case, they run after the DB commit step ...".CiteRef::gh:mw:code:deferred

FAQ

 * Does that mean that it will be impossible to set/update and query updated property value on the same page (e.g. when you update page properties via form and have #ask query at bottom)?CiteRef::mail:admin:mw:045677

It will not mean that updates are impossible, it means it requires other processes (mainly MediaWikis's edit save process) to be finished first therefore it is important that third-party extensions that wish to store additional data (e.g. ) are using the official hooks to ensure that data are processed in accordance to the deferred update plan.

Self-reference queries (those that query an entity using the "page name"  as condition) were not guaranteedCiteRef::gh:smw:1478:202170690 to be updated visually on the same save event and that remains so whether deferred updates are used or not.