public override ISqlValue Divide(ISqlValue a, ISqlValue b)
{
if (!(a is SqlNumber) ||
!(b is SqlNumber))
{
return(SqlNull.Value);
}
var x = (SqlNumber)a;
var y = (SqlNumber)b;
return(SqlMath.Divide(x, y, Precision));
}
public override ISqlValue Modulo(ISqlValue a, ISqlValue b)
{
if (!(a is SqlNumber) ||
!(b is SqlNumber))
{
return(SqlNull.Value);
}
var x = (SqlNumber)a;
var y = (SqlNumber)b;
return(SqlMath.Remainder(x, y));
}
public override ISqlValue Multiply(ISqlValue a, ISqlValue b)
{
if (!(a is SqlNumber) ||
!(b is SqlNumber))
{
return(SqlNull.Value);
}
var x = (SqlNumber)a;
var y = (SqlNumber)b;
return(SqlMath.Multiply(x, y));
}
private void RegisterAggregates()
{
// COUNT(*)
RegisterAggregate("COUNT", Deterministic("column"), PrimitiveTypes.VarNumeric(),
iterate => {
if (iterate.IsFirst)
{
iterate.SetResult(SqlObject.BigInt(1));
}
else
{
iterate.SetResult(iterate.Accumulation.Add(SqlObject.BigInt(1)));
}
},
initialize => {
var groupResolver = initialize.GetGroupResolver();
var groupSize = groupResolver.Size;
var argRef = (initialize.Input as SqlReferenceExpression)?.ReferenceName;
if (groupSize == 0 || (argRef != null && argRef.IsGlob))
{
initialize.SetResult(SqlExpression.Constant(SqlObject.BigInt(groupSize)), false);
}
return(Task.CompletedTask);
});
// MIN
RegisterAggregate("MIN", Deterministic("column"), PrimitiveTypes.VarNumeric(),
iterate => {
if (iterate.IsFirst)
{
iterate.SetResult(iterate.Current);
}
else if (iterate.Current.LessThan(iterate.Accumulation).IsTrue)
{
iterate.SetResult(iterate.Current);
}
});
// MAX
RegisterAggregate("MAX", Deterministic("column"), PrimitiveTypes.VarNumeric(),
iterate => {
if (iterate.IsFirst)
{
iterate.SetResult(iterate.Current);
}
else if (iterate.Current.GreaterThan(iterate.Accumulation).IsTrue)
{
iterate.SetResult(iterate.Current);
}
else if (iterate.Accumulation.LessThan(iterate.Current).IsTrue)
{
iterate.SetResult(iterate.Accumulation);
}
});
// AVG
RegisterAggregate("AVG", Deterministic("column"), PrimitiveTypes.VarNumeric(),
iterate => {
if (iterate.IsFirst)
{
iterate.SetResult(iterate.Current);
}
else
{
iterate.SetResult(iterate.Current.Add(iterate.Accumulation));
}
}, merge: merge => {
var groupResolver = merge.GetGroupResolver();
var groupSize = groupResolver.Size;
var final = merge.Accumulated.Divide(SqlObject.BigInt(groupSize));
merge.SetOutput(final);
return(Task.CompletedTask);
});
// STDEV
RegisterAggregate("STDEV", Deterministic("column"), PrimitiveTypes.VarNumeric(), iterate => {
var aggregator = (AvgAggregator)iterate.MethodContext.Metadata["aggregator"];
aggregator.Values.Add(iterate.Current);
if (iterate.IsFirst)
{
iterate.SetResult(iterate.Current);
}
else
{
iterate.SetResult(iterate.Current.Add(iterate.Accumulation));
}
}, initialize => {
var groupResolver = initialize.GetGroupResolver();
var aggregator = new AvgAggregator {
Values = new BigList <SqlObject>(groupResolver.Size)
};
initialize.MethodContext.Metadata["aggregator"] = aggregator;
return(Task.CompletedTask);
}, merge => {
var groupResolver = merge.GetGroupResolver();
var groupSize = groupResolver.Size;
var aggregator = (AvgAggregator)merge.MethodContext.Metadata["aggregator"];
var avg = merge.Accumulated.Divide(SqlObject.BigInt(groupSize));
var sums = aggregator.Values.Select(x => SqlMath.Pow((SqlNumber)x.Subtract(avg).Value, (SqlNumber)2));
var sum = SqlNumber.Zero;
foreach (var number in sums)
{
sum += number;
}
var ret = SqlMath.Sqrt(sum / (SqlNumber)(groupSize - 1));
merge.SetOutput(SqlObject.Numeric(ret));
return(Task.CompletedTask);
});
// SUM
RegisterAggregate("SUM", Deterministic("column"), PrimitiveTypes.VarNumeric(),
iterate => {
if (iterate.IsFirst)
{
iterate.SetResult(iterate.Current);
}
else
{
iterate.SetResult(iterate.Current.Add(iterate.Accumulation));
}
});
// LAST
RegisterAggregate("LAST", Deterministic("column"), new SqlDeterministicType(),
iterate => {
var groupResolver = iterate.GetGroupResolver();
var groupSize = groupResolver.Size;
if (iterate.Offset == groupSize - 1)
{
iterate.SetResult(iterate.Current);
}
else
{
iterate.SetResult(SqlObject.Null);
}
});
// FIRST
RegisterAggregate("FIRST", Deterministic("column"), new SqlDeterministicType(),
iterate => {
if (iterate.IsFirst)
{
iterate.SetResult(iterate.Current, false);
}
});
RegisterAggregate("GROUP_ID", PrimitiveTypes.Integer(),
iterate => {
// no-op
}, merge: merge => {
var groupResolver = merge.GetGroupResolver();
merge.SetOutput(SqlObject.Integer(groupResolver.GroupId));
return(Task.CompletedTask);
});
}
