title: Is there a notion of Global secondary Index in mongo?
body: <p>I understand Mongo supports secondary indexes, but it is local to the shard i.e Every shard will have its own index (containing just the documents in this shard) and those will will be accessed in parallel (every shard reads its own local index shard) and the results merged. I understand couchbase and dynamo has global secondary indexes so Instead of having multiple indexes on multiple nodes, a single node has a single index for the global data. This means an index lookup can be performed against just one node. Is there something similar available for Mongodb ? </p>
  
  <p>I could not find it from mongo's doc <a href="https://docs.mongodb.com/manual/indexes/" rel="nofollow noreferrer">https://docs.mongodb.com/manual/indexes/</a> </p>