zeroshade commented on code in PR #13806:
URL: https://github.com/apache/arrow/pull/13806#discussion_r939218404
##########
go/arrow/ipc/writer.go:
##########
@@ -574,6 +577,100 @@ func (w *recordEncoder) visit(p *Payload, arr
arrow.Array) error {
}
w.depth++
+ case *arrow.SparseUnionType:
+ offset, length := arr.Data().Offset(), arr.Len()
+ arr := arr.(*array.SparseUnion)
+ typeCodes := getTruncatedBuffer(int64(offset), int64(length),
int32(unsafe.Sizeof(arrow.UnionTypeCode(0))), arr.TypeCodes())
+ p.body = append(p.body, typeCodes)
+
+ w.depth--
+ for i := 0; i < arr.NumFields(); i++ {
+ err := w.visit(p, arr.Field(i))
+ if err != nil {
+ return fmt.Errorf("could not visit field %d of
sparse union array: %w", i, err)
+ }
+ }
+ w.depth++
+ case *arrow.DenseUnionType:
+ offset, length := arr.Data().Offset(), arr.Len()
+ arr := arr.(*array.DenseUnion)
+ typeCodes := getTruncatedBuffer(int64(offset), int64(length),
int32(unsafe.Sizeof(arrow.UnionTypeCode(0))), arr.TypeCodes())
+ p.body = append(p.body, typeCodes)
+
+ w.depth--
+ dt := arr.UnionType()
+
+ // union type codes are not necessarily 0-indexed
+ maxCode := dt.MaxTypeCode()
+
+ // allocate an array of child offsets. Set all to -1 to
indicate we
+ // haven't observed a first occurrence of a particular child yet
+ offsets := make([]int32, maxCode+1)
+ lengths := make([]int32, maxCode+1)
+ offsets[0], lengths[0] = -1, 0
+ for i := 1; i < len(offsets); i *= 2 {
+ copy(offsets[i:], offsets[:i])
+ copy(lengths[i:], lengths[:i])
+ }
+
+ var valueOffsets *memory.Buffer
+ if offset != 0 {
+ // this case sucks. Because the offsets are different
for each
+ // child array, when we have a sliced array, we need to
re-base
+ // the value offsets for each array! ew.
+
Review Comment:
created new function `rebaseDenseUnionValueOffsets`
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