Link Analysis Changes:

Index Updates:

• Increase base index size by 15%. 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%.
• New index tier. We keep our index in "tiers" where different documents are indexed at different rates depending on how relevant they are likely to be to users. This month we introduced an additional indexing tier to support continued comprehensiveness in search results.