Google publishes a list every month to keep us aware of the changes coming to their search quality. April is no different and it's a massive update containing 53 changes from domain diversity to better HTML5 resource caching.
This month's update contains one particularly interesting change though. Google will be increasing the base index size by 15 percent. Under the codename "indexing," Google describes the change as thus:
The base search index is our main index for serving search results and every query that comes into Google is matched against this index. This change increases the number of documents served by that index by 15%. *Note: We’re constantly tuning the size of our different indexes and changes may not always appear in these blog posts.
Related to the increased base index size, Google will also be introducing a new index tier. As you might be aware, Google keeps their index in these "tiers" where documents are indexed at different rates depending on their relevance. The new tier should increase the comprehensiveness of search for all users.
There's another 51 changes to go and they range from fascinating to interesting. One of particular note is Google's introduction of instant answers for the MLB season. Just trying typing sf giants score into Google and get the latest updates.