}
return ExprType.SIMPLE_PROJECT;
} else if (leaf instanceof POUserFunc) {
POUserFunc userFunc = (POUserFunc)leaf;
if(!userFunc.combinable() ){
return ExprType.NOT_ALGEBRAIC;
}
// The leaf userFunc may be combinable, but there might be other
// algebraic userFuncs in the predecessors, if there are
// we choose not to fire combiner.