feat(stdlib): create a version of map that is columnar

The columnar version of map will run map over an entire table chunk
rather than running it and then appending per row. This version of map
should be more efficient in the normal cases and be more amenable to
vectorized functions.

Related to #4186.

array/array.go

@@ -167,6 +167,9 @@ func (a *String) ValueLen(i int) int {
 	}
 	return len(a.value)
 }
+func (a *String) IsConstant() bool {
+	return a.data == nil
+}
 
 type sliceable interface {
 	Slice(i, j int) Interface

internal/feature/flags.yml

@@ -33,3 +33,9 @@
   key: queryConcurrencyLimit
   default: 0
   contact: Jonathan Sternberg
+
+- name: Vectorized Map
+  description: Enables the version of map that supports vectorized functions
+  key: vectorizedMap
+  default: false
+  contact: Jonathan Sternberg

stdlib/universe/map.go

@@ -9,6 +9,7 @@ import (
 	"github.com/influxdata/flux/compiler"
 	"github.com/influxdata/flux/execute"
 	"github.com/influxdata/flux/internal/errors"
+	"github.com/influxdata/flux/internal/feature"
 	"github.com/influxdata/flux/interpreter"
 	"github.com/influxdata/flux/plan"
 	"github.com/influxdata/flux/runtime"
@@ -101,6 +102,11 @@ func createMapTransformation(id execute.DatasetID, mode execute.AccumulationMode
 	if !ok {
 		return nil, nil, errors.Newf(codes.Internal, "invalid spec type %T", spec)
 	}
+
+	if feature.VectorizedMap().Enabled(a.Context()) {
+		return newMapTransformation2(a.Context(), id, s, a.Allocator())
+	}
+
 	cache := execute.NewTableBuilderCache(a.Allocator())
 	d := execute.NewDataset(id, mode, cache)
 	t, err := NewMapTransformation(a.Context(), s, d, cache)

stdlib/universe/map2.gen.go

@@ -0,0 +1,129 @@
+// Generated by tmpl
+// https://github.com/benbjohnson/tmpl
+//
+// DO NOT EDIT!
+// Source: map2.gen.go.tmpl
+
+package universe
+
+import (
+	"fmt"
+
+	"github.com/influxdata/flux/array"
+)
+
+func (m *mapTransformation2) isConstant(arr array.Interface) bool {
+	switch arr := arr.(type) {
+	case *array.Int:
+		return m.isIntConstant(arr)
+	case *array.Uint:
+		return m.isUintConstant(arr)
+	case *array.Float:
+		return m.isFloatConstant(arr)
+	case *array.String:
+		return m.isStringConstant(arr)
+	case *array.Boolean:
+		return m.isBooleanConstant(arr)
+
+	default:
+		panic(fmt.Errorf("unsupported array datat ype: %s", arr.DataType()))
+	}
+}
+
+func (m *mapTransformation2) isIntConstant(arr *array.Int) bool {
+	// If all values are null, then that is still constant.
+	if arr.NullN() == arr.Len() {
+		return true
+	} else if arr.NullN() > 0 {
+		// At least one value is null, but not all so
+		// not constant by definition.
+		return false
+	}
+
+	// All values are non-null so check if they are all the same.
+	v := arr.Value(0)
+	for i, n := 1, arr.Len(); i < n; i++ {
+		if arr.Value(i) != v {
+			return false
+		}
+	}
+	return true
+
+}
+
+func (m *mapTransformation2) isUintConstant(arr *array.Uint) bool {
+	// If all values are null, then that is still constant.
+	if arr.NullN() == arr.Len() {
+		return true
+	} else if arr.NullN() > 0 {
+		// At least one value is null, but not all so
+		// not constant by definition.
+		return false
+	}
+
+	// All values are non-null so check if they are all the same.
+	v := arr.Value(0)
+	for i, n := 1, arr.Len(); i < n; i++ {
+		if arr.Value(i) != v {
+			return false
+		}
+	}
+	return true
+
+}
+
+func (m *mapTransformation2) isFloatConstant(arr *array.Float) bool {
+	// If all values are null, then that is still constant.
+	if arr.NullN() == arr.Len() {
+		return true
+	} else if arr.NullN() > 0 {
+		// At least one value is null, but not all so
+		// not constant by definition.
+		return false
+	}
+
+	// All values are non-null so check if they are all the same.
+	v := arr.Value(0)
+	for i, n := 1, arr.Len(); i < n; i++ {
+		if arr.Value(i) != v {
+			return false
+		}
+	}
+	return true
+
+}
+
+func (m *mapTransformation2) isStringConstant(arr *array.String) bool {
+	// If all values are null, then that is still constant.
+	if arr.NullN() == arr.Len() {
+		return true
+	} else if arr.NullN() > 0 {
+		// At least one value is null, but not all so
+		// not constant by definition.
+		return false
+	}
+
+	return arr.IsConstant()
+
+}
+
+func (m *mapTransformation2) isBooleanConstant(arr *array.Boolean) bool {
+	// If all values are null, then that is still constant.
+	if arr.NullN() == arr.Len() {
+		return true
+	} else if arr.NullN() > 0 {
+		// At least one value is null, but not all so
+		// not constant by definition.
+		return false
+	}
+
+	// All values are non-null so check if they are all the same.
+	v := arr.Value(0)
+	for i, n := 1, arr.Len(); i < n; i++ {
+		if arr.Value(i) != v {
+			return false
+		}
+	}
+	return true
+
+}

stdlib/universe/map2.gen.go.tmpl

@@ -0,0 +1,43 @@
+package universe
+
+import (
+	"fmt"
+
+	"github.com/influxdata/flux/array"
+)
+
+func (m *mapTransformation2) isConstant(arr array.Interface) bool {
+	switch arr := arr.(type) {
+	{{range .}}case *array.{{.Name}}:
+		return m.is{{.Name}}Constant(arr)
+	{{end}}
+	default:
+		panic(fmt.Errorf("unsupported array datat ype: %s", arr.DataType()))
+	}
+}
+
+{{range .}}
+func (m *mapTransformation2) is{{.Name}}Constant(arr *array.{{.Name}}) bool {
+	// If all values are null, then that is still constant.
+	if arr.NullN() == arr.Len() {
+		return true
+	} else if arr.NullN() > 0 {
+		// At least one value is null, but not all so
+		// not constant by definition.
+		return false
+	}
+
+	{{if eq .Name "String"}}
+	return arr.IsConstant()
+	{{else}}
+	// All values are non-null so check if they are all the same.
+	v := arr.Value(0)
+	for i, n := 1, arr.Len(); i < n; i++ {
+		if arr.Value(i) != v {
+			return false
+		}
+	}
+	return true
+	{{end}}
+}
+{{end}}