Implement AVG, COUNT, MAX, MIN, SUM functions

parsers/models.go

@@ -119,9 +119,23 @@ const (
 	FunctionCallSetIntersect FunctionCallType = "SetIntersect"
 	FunctionCallSetUnion     FunctionCallType = "SetUnion"
 
+	FunctionCallAggregateAvg   FunctionCallType = "AggregateAvg"
+	FunctionCallAggregateCount FunctionCallType = "AggregateCount"
+	FunctionCallAggregateMax   FunctionCallType = "AggregateMax"
+	FunctionCallAggregateMin   FunctionCallType = "AggregateMin"
+	FunctionCallAggregateSum   FunctionCallType = "AggregateSum"
+
 	FunctionCallIn FunctionCallType = "In"
 )
 
+var AggregateFunctions = []FunctionCallType{
+	FunctionCallAggregateAvg,
+	FunctionCallAggregateCount,
+	FunctionCallAggregateMax,
+	FunctionCallAggregateMin,
+	FunctionCallAggregateSum,
+}
+
 type FunctionCall struct {
 	Arguments []interface{}
 	Type      FunctionCallType

parsers/nosql/aggregate_functions_test.go

@@ -0,0 +1,130 @@
+package nosql_test
+
+import (
+	"testing"
+
+	"github.com/pikami/cosmium/parsers"
+)
+
+func Test_Parse_AggregateFunctions(t *testing.T) {
+
+	t.Run("Should parse function AVG()", func(t *testing.T) {
+		testQueryParse(
+			t,
+			`SELECT AVG(c.a1) FROM c`,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Type: parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateAvg,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "a1"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+		)
+	})
+
+	t.Run("Should parse function COUNT()", func(t *testing.T) {
+		testQueryParse(
+			t,
+			`SELECT COUNT(c.a1) FROM c`,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Type: parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateCount,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "a1"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+		)
+	})
+
+	t.Run("Should parse function MAX()", func(t *testing.T) {
+		testQueryParse(
+			t,
+			`SELECT MAX(c.a1) FROM c`,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Type: parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateMax,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "a1"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+		)
+	})
+
+	t.Run("Should parse function MIN()", func(t *testing.T) {
+		testQueryParse(
+			t,
+			`SELECT MIN(c.a1) FROM c`,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Type: parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateMin,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "a1"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+		)
+	})
+
+	t.Run("Should parse function SUM()", func(t *testing.T) {
+		testQueryParse(
+			t,
+			`SELECT SUM(c.a1) FROM c`,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Type: parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateSum,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "a1"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+		)
+	})
+}

parsers/nosql/nosql.peg

@@ -327,6 +327,7 @@ FunctionCall <- StringFunctions
     / TypeCheckingFunctions
     / ArrayFunctions
     / InFunction
+    / AggregateFunctions
 
 StringFunctions <- StringEqualsExpression
     / ToStringExpression
@@ -356,6 +357,12 @@ TypeCheckingFunctions <- IsDefined
     / IsPrimitive
     / IsString
 
+AggregateFunctions <- AvgAggregateExpression
+    / CountAggregateExpression
+    / MaxAggregateExpression
+    / MinAggregateExpression
+    / SumAggregateExpression
+
 ArrayFunctions <- ArrayConcatExpression
     / ArrayLengthExpression
     / ArraySliceExpression
@@ -509,6 +516,26 @@ InFunction <- ex1:SelectProperty ws "IN"i ws "(" ws ex2:SelectItem others:(ws ",
     return createFunctionCall(parsers.FunctionCallIn, append([]interface{}{ex1, ex2}, others.([]interface{})...))
 }
 
+AvgAggregateExpression   <- "AVG"i "(" ws ex:SelectItem  ws ")" {
+    return createFunctionCall(parsers.FunctionCallAggregateAvg, []interface{}{ex})
+}
+
+CountAggregateExpression <- "COUNT"i "(" ws ex:SelectItem ws ")" {
+    return createFunctionCall(parsers.FunctionCallAggregateCount, []interface{}{ex})
+}
+
+MaxAggregateExpression   <- "MAX"i "(" ws ex:SelectItem ws ")" {
+    return createFunctionCall(parsers.FunctionCallAggregateMax, []interface{}{ex})
+}
+
+MinAggregateExpression   <- "MIN"i "(" ws ex:SelectItem ws ")" {
+    return createFunctionCall(parsers.FunctionCallAggregateMin, []interface{}{ex})
+}
+
+SumAggregateExpression   <- "SUM"i "(" ws ex:SelectItem ws ")" {
+    return createFunctionCall(parsers.FunctionCallAggregateSum, []interface{}{ex})
+}
+
 Integer <- [0-9]+ {
     return strconv.Atoi(string(c.text))
 }

query_executors/memory_executor/aggregate_functions.go

@@ -0,0 +1,131 @@
+package memoryexecutor
+
+import (
+	"math"
+
+	"github.com/pikami/cosmium/parsers"
+)
+
+func (c memoryExecutorContext) aggregate_Avg(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	sum := 0.0
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				sum += numericValue
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				sum += float64(numericValue)
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return sum / float64(count)
+	} else {
+		return nil
+	}
+}
+
+func (c memoryExecutorContext) aggregate_Count(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if value != nil {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func (c memoryExecutorContext) aggregate_Max(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	max := 0.0
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				if numericValue > max {
+					max = numericValue
+				}
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				if float64(numericValue) > max {
+					max = float64(numericValue)
+				}
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return max
+	} else {
+		return nil
+	}
+}
+
+func (c memoryExecutorContext) aggregate_Min(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	min := math.MaxFloat64
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				if numericValue < min {
+					min = numericValue
+				}
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				if float64(numericValue) < min {
+					min = float64(numericValue)
+				}
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return min
+	} else {
+		return nil
+	}
+}
+
+func (c memoryExecutorContext) aggregate_Sum(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	sum := 0.0
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				sum += numericValue
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				sum += float64(numericValue)
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return sum
+	} else {
+		return nil
+	}
+}

query_executors/memory_executor/aggregate_functions_test.go

@@ -0,0 +1,210 @@
+package memoryexecutor_test
+
+import (
+	"testing"
+
+	"github.com/pikami/cosmium/parsers"
+	memoryexecutor "github.com/pikami/cosmium/query_executors/memory_executor"
+)
+
+func Test_Execute_AggregateFunctions(t *testing.T) {
+	mockData := []memoryexecutor.RowType{
+		map[string]interface{}{"id": "123", "number": 123, "key": "a"},
+		map[string]interface{}{"id": "456", "number": 456, "key": "a"},
+		map[string]interface{}{"id": "789", "number": 789, "key": "b"},
+		map[string]interface{}{"id": "no-number", "key": "b"},
+	}
+
+	t.Run("Should execute function AVG()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+					{
+						Alias: "avg",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateAvg,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "number"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				GroupBy: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"key": "a", "avg": 289.5},
+				map[string]interface{}{"key": "b", "avg": 789.0},
+			},
+		)
+	})
+
+	t.Run("Should execute function AVG() without GROUP BY clause", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Alias: "avg",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateAvg,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "number"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"avg": 456.0},
+			},
+		)
+	})
+
+	t.Run("Should execute function COUNT()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+					{
+						Alias: "cnt",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateCount,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "number"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				GroupBy: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"key": "a", "cnt": 2},
+				map[string]interface{}{"key": "b", "cnt": 1},
+			},
+		)
+	})
+
+	t.Run("Should execute function MAX()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+					{
+						Alias: "max",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateMax,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "number"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				GroupBy: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"key": "a", "max": 456.0},
+				map[string]interface{}{"key": "b", "max": 789.0},
+			},
+		)
+	})
+
+	t.Run("Should execute function MIN()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+					{
+						Alias: "min",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateMin,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "number"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				GroupBy: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"key": "a", "min": 123.0},
+				map[string]interface{}{"key": "b", "min": 789.0},
+			},
+		)
+	})
+
+	t.Run("Should execute function SUM()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+					{
+						Alias: "sum",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallAggregateSum,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "number"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				GroupBy: []parsers.SelectItem{
+					{Path: []string{"c", "key"}},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"key": "a", "sum": 579.0},
+				map[string]interface{}{"key": "b", "sum": 789.0},
+			},
+		)
+	})
+}

query_executors/memory_executor/memory_executor.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/pikami/cosmium/internal/logger"
 	"github.com/pikami/cosmium/parsers"
+	"golang.org/x/exp/slices"
 )
 
 type RowType interface{}
@@ -45,9 +46,16 @@ func Execute(query parsers.SelectStmt, data []RowType) []RowType {
 	// Apply select
 	if !isGroupSelect {
 		selectedData := make([]RowType, 0)
-		for _, row := range result {
-			selectedData = append(selectedData, ctx.selectRow(query.SelectItems, row))
+		if hasAggregateFunctions(query.SelectItems) {
+			// When can have aggregate functions without GROUP BY clause,
+			// we should aggregate all rows in that case
+			selectedData = append(selectedData, ctx.selectRow(query.SelectItems, result))
+		} else {
+			for _, row := range result {
+				selectedData = append(selectedData, ctx.selectRow(query.SelectItems, row))
+			}
 		}
+
 		result = selectedData
 	}
 
@@ -275,6 +283,17 @@ func (c memoryExecutorContext) getFieldValue(field parsers.SelectItem, row RowTy
 		case parsers.FunctionCallSetUnion:
 			return c.set_Union(typedValue.Arguments, rowValue)
 
+		case parsers.FunctionCallAggregateAvg:
+			return c.aggregate_Avg(typedValue.Arguments, row)
+		case parsers.FunctionCallAggregateCount:
+			return c.aggregate_Count(typedValue.Arguments, row)
+		case parsers.FunctionCallAggregateMax:
+			return c.aggregate_Max(typedValue.Arguments, row)
+		case parsers.FunctionCallAggregateMin:
+			return c.aggregate_Min(typedValue.Arguments, row)
+		case parsers.FunctionCallAggregateSum:
+			return c.aggregate_Sum(typedValue.Arguments, row)
+
 		case parsers.FunctionCallIn:
 			return c.misc_In(typedValue.Arguments, rowValue)
 		}
@@ -431,3 +450,23 @@ func deduplicate(slice []RowType) []RowType {
 
 	return result
 }
+
+func hasAggregateFunctions(selectItems []parsers.SelectItem) bool {
+	if selectItems == nil {
+		return false
+	}
+
+	for _, selectItem := range selectItems {
+		if selectItem.Type == parsers.SelectItemTypeFunctionCall {
+			if typedValue, ok := selectItem.Value.(parsers.FunctionCall); ok && slices.Contains[[]parsers.FunctionCallType](parsers.AggregateFunctions, typedValue.Type) {
+				return true
+			}
+		}
+
+		if hasAggregateFunctions(selectItem.SelectItems) {
+			return true
+		}
+	}
+
+	return false
+}