I would like to remove the 'high cardinality dimension' feature in mondrian 4.0.

To specify that a dimension is high-cardinality, you set the highCardinality attribute of the Dimension element to true. This will cause mondrian to scan over the dimension, rather than trying to load all of the children of a given parent member into memory.

The goal is a worthy one, but the implementation — making iterators look like lists — has a number of architectural problems: it duplicates code; because it allows backtracking for a fixed amount, it works with small dimensions but unpredictably fails with larger ones; and because lists are based on iterators, re-starting an iteration multiple times (e.g. from within a crossjoin) can re-execute complex SQL statements.

There are other architectural features designed to …