func (af *avgFunction) calculateResult(ctx *ast.AggEvaluateContext) (d types.Datum) {
switch ctx.Value.Kind() {
case types.KindFloat64:
t := ctx.Value.GetFloat64() / float64(ctx.Count)
d.SetValue(t)
case types.KindMysqlDecimal:
x := ctx.Value.GetMysqlDecimal()
y := mysql.NewDecFromInt(ctx.Count)
to := new(mysql.MyDecimal)
mysql.DecimalDiv(x, y, to, mysql.DivFracIncr)
to.Round(to, ctx.Value.Frac()+mysql.DivFracIncr)
d.SetMysqlDecimal(to)
}
return
}
func (e *Evaluator) evalAggAvg(v *ast.AggregateFuncExpr) {
ctx := v.GetContext()
switch ctx.Value.Kind() {
case types.KindFloat64:
t := ctx.Value.GetFloat64() / float64(ctx.Count)
v.SetValue(t)
case types.KindMysqlDecimal:
x := ctx.Value.GetMysqlDecimal()
var y, to mysql.MyDecimal
y.FromUint(uint64(ctx.Count))
mysql.DecimalDiv(x, &y, &to, mysql.DivFracIncr)
to.Round(&to, ctx.Value.Frac()+mysql.DivFracIncr)
v.SetMysqlDecimal(&to)
}
ctx.Value = *v.GetDatum()
}
// GetGroupResult implements AggregationFunction interface.
func (af *avgFunction) GetGroupResult(groupKey []byte) (d types.Datum) {
ctx := af.getContext(groupKey)
switch ctx.Value.Kind() {
case types.KindFloat64:
t := ctx.Value.GetFloat64() / float64(ctx.Count)
d.SetValue(t)
case types.KindMysqlDecimal:
x := ctx.Value.GetMysqlDecimal()
y := mysql.NewDecFromInt(ctx.Count)
to := new(mysql.MyDecimal)
mysql.DecimalDiv(x, y, to, mysql.DivFracIncr)
to.Round(to, ctx.Value.Frac()+mysql.DivFracIncr)
d.SetMysqlDecimal(to)
}
return
}
// ComputeDiv computes the result of a/b.
func ComputeDiv(a, b Datum) (d Datum, err error) {
// MySQL support integer division Div and division operator /
// we use opcode.Div for division operator and will use another for integer division later.
// for division operator, we will use float64 for calculation.
switch a.Kind() {
case KindFloat64:
y, err1 := b.ToFloat64()
if err1 != nil {
return d, errors.Trace(err1)
}
if y == 0 {
return d, nil
}
x := a.GetFloat64()
d.SetFloat64(x / y)
return d, nil
default:
// the scale of the result is the scale of the first operand plus
// the value of the div_precision_increment system variable (which is 4 by default)
// we will use 4 here
xa, err1 := a.ToDecimal()
if err != nil {
return d, errors.Trace(err1)
}
xb, err1 := b.ToDecimal()
if err1 != nil {
return d, errors.Trace(err1)
}
// division by zero return null
to := new(mysql.MyDecimal)
err = mysql.DecimalDiv(xa, xb, to, mysql.DivFracIncr)
if err != mysql.ErrDivByZero {
d.SetMysqlDecimal(to)
} else {
err = nil
}
return d, err
}
}
// ComputeIntDiv computes the result of a / b, both a and b are integer.
func ComputeIntDiv(a, b Datum) (d Datum, err error) {
switch a.Kind() {
case KindInt64:
x := a.GetInt64()
switch b.Kind() {
case KindInt64:
y := b.GetInt64()
if y == 0 {
return d, nil
}
r, err1 := DivInt64(x, y)
d.SetInt64(r)
return d, errors.Trace(err1)
case KindUint64:
y := b.GetUint64()
if y == 0 {
return d, nil
}
r, err1 := DivIntWithUint(x, y)
d.SetUint64(r)
return d, errors.Trace(err1)
}
case KindUint64:
x := a.GetUint64()
switch b.Kind() {
case KindInt64:
y := b.GetInt64()
if y == 0 {
return d, nil
}
r, err1 := DivUintWithInt(x, y)
d.SetUint64(r)
return d, errors.Trace(err1)
case KindUint64:
y := b.GetUint64()
if y == 0 {
return d, nil
}
d.SetUint64(x / y)
return d, nil
}
}
// If either is not integer, use decimal to calculate
x, err := a.ToDecimal()
if err != nil {
return d, errors.Trace(err)
}
y, err := b.ToDecimal()
if err != nil {
return d, errors.Trace(err)
}
to := new(mysql.MyDecimal)
err = mysql.DecimalDiv(x, y, to, mysql.DivFracIncr)
if err == mysql.ErrDivByZero {
return d, nil
}
iVal, err1 := to.ToInt()
if err == nil {
err = err1
}
d.SetInt64(iVal)
return d, nil
}