// override RexShuttle
public RexNode visitCall(final RexCall call) {
int i = reducibleExps.indexOf(call);
if (i == -1) {
return super.visitCall(call);
}
RexNode replacement = reducedValues.get(i);
if (addCasts.get(i) && (replacement.getType() != call.getType())) {
// Handle change from nullable to NOT NULL by claiming
// that the result is still nullable, even though
// we know it isn't.
//
// Also, we cannot reduce CAST('abc' AS VARCHAR(4)) to 'abc'.
// If we make 'abc' of type VARCHAR(4), we may later encounter
// the same expression in a ProjectRel's digest where it has
// type VARCHAR(3), and that's wrong.
replacement = rexBuilder.makeCast(call.getType(), replacement);
}
return replacement;
}
private void reduceCasts(RexCall outerCast) {
RexNode[] operands = outerCast.getOperands();
if (operands.length != 1) {
return;
}
RelDataType outerCastType = outerCast.getType();
RelDataType operandType = operands[0].getType();
if (operandType.equals(outerCastType)) {
removableCasts.add(outerCast);
return;
}
// See if the reduction
// CAST((CAST x AS type) AS type NOT NULL)
// -> CAST(x AS type NOT NULL)
// applies. TODO jvs 15-Dec-2008: consider
// similar cases for precision changes.
if (!(operands[0] instanceof RexCall)) {
return;
}
RexCall innerCast = (RexCall) operands[0];
if (innerCast.getOperator() != SqlStdOperatorTable.castFunc) {
return;
}
if (innerCast.getOperands().length != 1) {
return;
}
RelDataTypeFactory typeFactory = preparingStmt.getFarragoTypeFactory();
RelDataType outerTypeNullable = typeFactory.createTypeWithNullability(outerCastType, true);
RelDataType innerTypeNullable = typeFactory.createTypeWithNullability(operandType, true);
if (outerTypeNullable != innerTypeNullable) {
return;
}
if (operandType.isNullable()) {
removableCasts.add(innerCast);
}
}