This feature has been rolled out to all production tenants, on the road map the feature description is:
Over the coming months, we will be phasing in automatic indexing and performance optimization to improve performance of large lists and reduce or eliminate problems in large scale lists.
But what does that really mean?
As you may know the current item limit for a list is 30 Million this is a massive number and to work better with large datasets like that you would want to use indexes, in comes Predictive Indexing to automatically create those indexes based on views without user intervention allowing you to focus on the experience and not the technicalities under the hood.
The rules for this are the following:
- Available in Modern UI only
- Works when item is between 2,500 – 19,999 items
- Created when you sort a list or filter a view
- Only works with the following column types (The column that you sort)
- Single line or Multiple line of text
- Single or Multiple Value
Well this is all great but what does that do for the end user? And the end result is that while you still have List/Library thresholds of 5,000 we can now view large lists without filtering or getting blocked by throttling, because we will use the index (By default on modified date column) to improve performance on viewability.
You can see the ignite presentation of this here (Note: at 42:31 is when they talk about this feature, although the whole video is awesome)