In one aspect, a data item is written to a data chunk of a stream segment. The stream segment includes a stream segment header and a plurality of data chunks. A first identifier of the data item is written to the stream segment header of the stream segment. A second identifier of the data item is written to a header of the data chunk of the stream segment. In another aspect, a stream segment header of a stream segment is queried with a query identifier. The querying identifies if any of the data items in the data chunks of the stream segment have the query identifier. If any of the data items in the data chunks of the stream segment have the query identifier, the data chunks of the stream segment are queried with the query identifier to identify which data chunks of the stream segment have the query identifier.