In this paper, we deal with the problem of determining the best possible physical implementation of an ETL workflow, given its logical-level description and an appropriate cost model as inputs. We formulate the problem as a state-space problem and provide a suitable solution for this task. We further extend this technique by intentionally introducing sorter activities in the workflow in order to search for alternative physical implementations with lower cost. We experimentally assess our method based on a principled organization of test suites. Categories and Subject Descriptors H.2.1 [Database Management]: Logical Design--data models, schema and subschema General Terms Algorithms, Design Keywords Data Warehousing, ETL, Physical Design, Optimization