What are continuous crawls?
Continuous crawls help to keep the search index and search results as fresh as possible. This is a new feature in SharePoint 2013.
Because of changes in how the index is created and stored, a document can appear in the index within seconds of going through the content processing component – you no longer have to wait for long index merges until it shows in results.
It also means you can get the latest changes even while a full crawl is starting, so you can see results before full crawl completes.
Note: It only works with SharePoint sites as content sources.
When should I use them?
You should use this feature for your search driven applications. Everytime when it matters that new results appear right after they have been created.
The new Newsfeed in My Sites and Team Sites uses search, for example:
Enabling continuous crawl has the following advantages:
- The search results are very fresh, because the SharePoint content is crawled frequently to keep the search index up to date.
- The search administrator does not have to monitor changing or seasonal demands for content freshness. Continuous crawls automatically adapt as necessary to the change rate of the SharePoint content.
How do they work?
Continuous crawls run every 15 minutes by default. When running, the crawler gets changes from SharePoint sites and pushes them to the content processing component.
The document will get processed by the content processing component on the fly. No index has to be merged. Items appear in the search results right after they have been crawled.
How do I configure them?
Step 1 – Edit the content source settings for your SharePoint sites
Step 2 – Change the crawl schedules to “Enable Continuous Crawls”
Step 3 – Change the interval for the continues crawls (optional)
The interval of 15 minutes is the default value, but you can change is with the PowerShell cmdlet Set-SPEnterpriseSearchCrawlContentSource.
For a medium Internet sites (FIS) topology (optimized for 3,400,000 items, processing 240 documents per second, and a usage pattern of 85 page views per second, which corresponds to 129 queries per second) Microsoft recommends that you enable continuous crawl with an interval of one minute, instead of the default interval of 15 minutes.
You can use Crawl health reports to monitor performance and react on performance issues:
- Central Administration > Application Management > Manage service applications > Search service application > Diagnostics > Crawl Health Reports
Want to learn more?
- Manage continuous crawls in SharePoint 2013 Preview
- Use search diagnostics in SharePoint Server 2013 Preview
- Scale search for performance and availability in SharePoint 2013 Preview