ipc/schema/array: avoid unnecessary allocations from Schema.Fields

Some for loops can be replaced with an iteration over schema field indices rather than a copy of the fields. This reduces allocations.
asubiotto · Nov 28, 2023 · cea1ffc · cea1ffc
1 parent 054464a
commit cea1ffc
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Showing 4 changed files with 11 additions and 11 deletions.
diff --git a/go/arrow/array/record.go b/go/arrow/array/record.go
@@ -185,7 +185,7 @@ func (rec *simpleRecord) validate() error {
 		return nil
 	}
 
-	if len(rec.arrs) != len(rec.schema.Fields()) {
+	if len(rec.arrs) != rec.schema.NumFields() {
 		return fmt.Errorf("arrow/array: number of columns/fields mismatch")
 	}
 
@@ -288,8 +288,8 @@ func NewRecordBuilder(mem memory.Allocator, schema *arrow.Schema) *RecordBuilder
 		fields:   make([]Builder, schema.NumFields()),
 	}
 
-	for i, f := range schema.Fields() {
-		b.fields[i] = NewBuilder(b.mem, f.Type)
+	for i := 0; i < schema.NumFields(); i++ {
+		b.fields[i] = NewBuilder(b.mem, schema.Field(i).Type)
 	}
 
 	return b
@@ -397,8 +397,8 @@ func (b *RecordBuilder) UnmarshalJSON(data []byte) error {
 		}
 	}
 
-	for i, f := range b.schema.Fields() {
-		if !keylist[f.Name] {
+	for i := 0; i < b.schema.NumFields(); i++ {
+		if !keylist[b.schema.Field(i).Name] {
 			b.fields[i].AppendNull()
 		}
 	}

diff --git a/go/arrow/ipc/file_reader.go b/go/arrow/ipc/file_reader.go
@@ -352,8 +352,8 @@ func newRecord(schema *arrow.Schema, memo *dictutils.Memo, meta *memory.Buffer,
 
 	pos := dictutils.NewFieldPos()
 	cols := make([]arrow.Array, schema.NumFields())
-	for i, field := range schema.Fields() {
-		data := ctx.loadArray(field.Type)
+	for i := 0; i < schema.NumFields(); i++ {
+		data := ctx.loadArray(schema.Field(i).Type)
 		defer data.Release()
 
 		if err := dictutils.ResolveFieldDict(memo, data, pos.Child(int32(i)), mem); err != nil {

diff --git a/go/arrow/ipc/metadata.go b/go/arrow/ipc/metadata.go
@@ -1102,8 +1102,8 @@ func schemaFromFB(schema *flatbuf.Schema, memo *dictutils.Memo) (*arrow.Schema,
 func schemaToFB(b *flatbuffers.Builder, schema *arrow.Schema, memo *dictutils.Mapper) flatbuffers.UOffsetT {
 	fields := make([]flatbuffers.UOffsetT, schema.NumFields())
 	pos := dictutils.NewFieldPos()
-	for i, field := range schema.Fields() {
-		fields[i] = fieldToFB(b, pos.Child(int32(i)), field, memo)
+	for i := 0; i < schema.NumFields(); i++ {
+		fields[i] = fieldToFB(b, pos.Child(int32(i)), schema.Field(i), memo)
 	}
 
 	flatbuf.SchemaStartFieldsVector(b, len(fields))

diff --git a/go/arrow/schema.go b/go/arrow/schema.go
@@ -260,7 +260,7 @@ func (s *Schema) AddField(i int, field Field) (*Schema, error) {
 func (s *Schema) String() string {
 	o := new(strings.Builder)
 	fmt.Fprintf(o, "schema:\n  fields: %d\n", s.NumFields())
-	for i, f := range s.Fields() {
+	for i, f := range s.fields {
 		if i > 0 {
 			o.WriteString("\n")
 		}
@@ -282,7 +282,7 @@ func (s *Schema) Fingerprint() string {
 
 	var b strings.Builder
 	b.WriteString("S{")
-	for _, f := range s.Fields() {
+	for _, f := range s.fields {
 		fieldFingerprint := f.Fingerprint()
 		if fieldFingerprint == "" {
 			return ""