A system for determining an entity's security rating may include a ratings engine and a security database. The security database may include a manifest and a distributed index containing security records. Each of the security records may have a key (e.g., a network identifier of a network asset) and a value (e.g., security information associated with the network asset identified by the key). The keyspace may be partitioned into multiple key ranges. The manifest may contain references to segments of the distributed index. Each segment may be associated with a key range and may index a group of security records having keys within the key range. The manifest and the segments may be stored in an object storage system. The ratings engine may determine the security rating of an entity based on security records of the entity's network assets, which may be retrieved from the database.