Auto-indexing of DocDB
Lately, I've been working a lot with Cloudant, which is a distributed CouchDB platform with integrated Lucene search. I absolutely love the fact that you can define some sort of triggers that, when a document is inserted or updated, update the index to reflect that operation. Likewise, when a document is deleted, the corresponding indexes are deleted from Lucene.
This is particularly convenient as you don't have to manually sync your DB and your search index, everything happens automatically under the cover. It would be great to have that on top of Azure Storage or the upcoming DocDB (even though I reckon that DocDB already has a powerful and flexible indexing system out of the box).
Azure Search now supports automatically indexing data in DocumentDB. You can learn more about this feature here: http://azure.microsoft.com/en-us/documentation/articles/documentdb-search-indexer/