General guidelines and best practice for working with Cosmos DB
Querying documents in CosmosDB
Use FeedResponse to retrieve all hits
The documents in a collection might be stored in different partitions. When querying documents in a collection, the response will only contain documents from a single partition at a time, to retrieve your hits across all partitions you may utilize the the continuation token or the HasMoreResults property of the DocumentQuery.
Avoid expensive queries
CosmosDB uses indexes to find matches for the queries,
if there is not value for the indexed property, all instances will have to be checked to figure out if there is a match for the query.
This occurs in cases where we assert that a property
is null, so queries like this should be avoided.
Always try to assert on an existing value, if this is not possible modifying the data model should be considered.