The release of 3.0 means that we are free to focus on the greater features that we have in store for vNext, but that doesn’t mean that we aren’t still working on small features that are meant to make your life easier.
In this case, this feature is here to deal with index definition churn. Consider the case where you have a large database, and you want to define an index, but aren’t quite sure exactly what you want. This is especially the case when you are working with the more complex indexes. The problem is that creating the index would mean having to process all the data in your database. That is usually fine, because RavenDB can still operate normally under those conditions, but it also means that you have to wait for this to happen, check the results, make a change to the index, and so on.
Because of the way we are optimizing new index creation, we are trying to do as much as possible, as soon as possible. So by the time we expose partial results for the index, you are already waiting for too long. This isn’t a problem for standard usage, because this behavior reduces the overall time for indexing a new index, but it is a problem when you are developing, because it increase the time for first visible result.
Because of that, we have added this feature:
This will create a temporary test index:
This index is going to operate on a partial data set, instead of all the data, but aside from that, it is identical in all respects to any other index, and you can test it out using all the normal tools we offer. Once you have change the index definition to your liking, you can make the index permanent, which actually goes into processing all documents.
This make rapid index prototyping on a large dataset much easier.