A query restriction descriptor indicating one or more attributes of a data object of a multi-data-store storage system is determined at a client-side component of the system. The query restrictions descriptor is used to prepare at least a read set descriptor of a proposed transaction. The read set of the proposed transaction includes a query with a predicate directed to the one or more attributes. A transformation function is applied to the predicate, and the result of the transformation is included in the read set descriptor. The proposed transaction is sent to a journal manager of the system, which performs read-write conflict detection using the read set descriptor and write set descriptors of one or more previously-committed transactions.