...
A Sitecore index is updated according to different strategies. The standard configuration uses the same indexupdatestrategies as the Sitecore master and web indexes, which means we have the following strategies:
- Master - Synchronous
- Web - OnPublishEndAsynchronousSingleInstanceStrategy
The synchronous strategy updates the index whenever items are updated and the OnPublishEndAsynchronousSingleInstanceStrategy is triggered on publish end and will rebuild the index incrementally.
It is possible to add more update strategies to indexes. For instance, depending on publishing strategies, it could be an idea to add the remoteRebuild strategy to the web index. This ensures that if the master index is rebuild, then all the web indexes is also rebuild.
For a complete list of indexupdate strategies, we refer to Sitecore's documentation