1. A computer implemented method for generating code for an integrated data system, the computer-implemented method comprising: receiving a mixed data flow containing mixed data flow operators, the mixed data flow operators collectively defining operations to be performed to complete the mixed data flow, wherein a first of a plurality of runtime environments of distinct types is selected to perform a given one of the defined operations, wherein the given operation is dependent on at least one other operation performed in a second of the plurality of runtime environments; generating, based on the mixed data flow, a logical operator graph containing logical operators independent of the plurality of runtime environments; converting the logical operator graph to an extended query graph model in which the logical operators are converted to model operators associated with the plurality of runtime environments; analyzing the extended query graph model in order to pre-optimize code generation to include at least one of chunking and execution parallelism; subsequent to analyzing the extended query graph model, converting the extended query graph model via code generation by operation of one or more computer processors into an execution plan graph executable on the plurality of different types of runtime environments; and executing the execution plan graph by an execution engine that invokes a plurality of runtime engines, each runtime engine being of a distinct runtime engine type corresponding to a respective one of the plurality of runtime environments.