// decompose splits an aggregate function to two parts: a final mode function and a partial mode function. Currently // there are no differences between partial mode and complete mode, so we can confuse them. func (a *aggPushDownSolver) decompose(aggFunc expression.AggregationFunction, schema expression.Schema, id string) ([]expression.AggregationFunction, expression.Schema) { // Result is a slice because avg should be decomposed to sum and count. Currently we don't process this case. result := []expression.AggregationFunction{aggFunc.Clone()} for _, aggFunc := range result { schema = append(schema, &expression.Column{ ColName: model.NewCIStr(fmt.Sprintf("join_agg_%d", len(schema))), // useless but for debug FromID: id, Position: len(schema), RetType: aggFunc.GetType(), }) } aggFunc.SetArgs(expression.Schema2Exprs(schema[len(schema)-len(result):])) aggFunc.SetMode(expression.FinalMode) return result, schema }