1. A computer-implemented method of pipelining operations involving one or more data manipulation operations, the method comprising: performing a first operation that is to change data in one or more database structures in a database system from a first state to a second state, wherein the first operation is a data manipulation operation in a series of operations; and granting a second operation access to an in-memory representation of the data in the one or more database structures in the database system in the second state prior to a first time when the data in the one or more database structures in the database system is changed by the first operation to the second state, wherein the second operation is a query operation in the series of operations and wherein the second operation logically depends on the data in the one or more database structures in the database system in the second state; wherein each of the database structures in the database system is a relational data structure; wherein each operation in the series of operations has a one-to-one correspondence with a relational database statement in a series of relational database statements; and wherein results of the series of operations can be alternatively obtained by executing the series of relational database statements.