// / nullif(count(x) - 1, 0),
// .5)
final int nGroups = oldAggRel.getGroupCount();
RelDataTypeFactory typeFactory =
oldAggRel.getCluster().getTypeFactory();
final RexBuilder rexBuilder = oldAggRel.getCluster().getRexBuilder();
assert oldCall.getArgList().size() == 1 : oldCall.getArgList();
final int argOrdinal = oldCall.getArgList().get(0);
final RelDataType argType =
getFieldType(
oldAggRel.getChild(),
argOrdinal);
// final RexNode argRef = inputExprs.get(argOrdinal);
RexNode argRef = rexBuilder.makeCall(CastHighOp, inputExprs.get(argOrdinal));
inputExprs.set(argOrdinal, argRef);
final RexNode argSquared =
rexBuilder.makeCall(
SqlStdOperatorTable.MULTIPLY, argRef, argRef);
final int argSquaredOrdinal = lookupOrAdd(inputExprs, argSquared);
final RelDataType sumType =
typeFactory.createTypeWithNullability(
argType,
true);
final AggregateCall sumArgSquaredAggCall =
new AggregateCall(
new SqlSumAggFunction(sumType),
oldCall.isDistinct(),
ImmutableIntList.of(argSquaredOrdinal),
sumType,
null);
final RexNode sumArgSquared =
rexBuilder.addAggCall(
sumArgSquaredAggCall,
nGroups,
newCalls,
aggCallMapping,
ImmutableList.of(argType));
final AggregateCall sumArgAggCall =
new AggregateCall(
new SqlSumAggFunction(sumType),
oldCall.isDistinct(),
ImmutableIntList.of(argOrdinal),
sumType,
null);
final RexNode sumArg =
rexBuilder.addAggCall(
sumArgAggCall,
nGroups,
newCalls,
aggCallMapping,
ImmutableList.of(argType));
final RexNode sumSquaredArg =
rexBuilder.makeCall(
SqlStdOperatorTable.MULTIPLY, sumArg, sumArg);
final SqlAggFunction countAgg = SqlStdOperatorTable.COUNT;
final RelDataType countType = countAgg.getReturnType(typeFactory);
final AggregateCall countArgAggCall =
new AggregateCall(
countAgg,
oldCall.isDistinct(),
oldCall.getArgList(),
countType,
null);
final RexNode countArg =
rexBuilder.addAggCall(
countArgAggCall,
nGroups,
newCalls,
aggCallMapping,
ImmutableList.of(argType));
final RexNode avgSumSquaredArg =
rexBuilder.makeCall(
SqlStdOperatorTable.DIVIDE,
sumSquaredArg, countArg);
final RexNode diff =
rexBuilder.makeCall(
SqlStdOperatorTable.MINUS,
sumArgSquared, avgSumSquaredArg);
final RexNode denominator;
if (biased) {
denominator = countArg;
} else {
final RexLiteral one =
rexBuilder.makeExactLiteral(BigDecimal.ONE);
final RexNode nul =
rexBuilder.makeNullLiteral(countArg.getType().getSqlTypeName());
final RexNode countMinusOne =
rexBuilder.makeCall(
SqlStdOperatorTable.MINUS, countArg, one);
final RexNode countEqOne =
rexBuilder.makeCall(
SqlStdOperatorTable.EQUALS, countArg, one);
denominator =
rexBuilder.makeCall(
SqlStdOperatorTable.CASE,
countEqOne, nul, countMinusOne);
}
final RexNode div =
rexBuilder.makeCall(
SqlStdOperatorTable.DIVIDE, diff, denominator);
RexNode result = div;
if (sqrt) {
final RexNode half =
rexBuilder.makeExactLiteral(new BigDecimal("0.5"));
result =
rexBuilder.makeCall(
SqlStdOperatorTable.POWER, div, half);
}
return rexBuilder.makeCast(
oldCall.getType(), result);
}