This is an automated email from the ASF dual-hosted git repository.
zeroshade pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/arrow-go.git
The following commit(s) were added to refs/heads/main by this push:
new 2e264f0b feat(extensions): add VariantGet for path extraction from
variant arrays (#1206)
2e264f0b is described below
commit 2e264f0bfb1f3cfc788c4208bdb4c8fb40542847
Author: Neelesh Salian <[email protected]>
AuthorDate: Tue Sep 1 14:16:53 2026 -0700
feat(extensions): add VariantGet for path extraction from variant arrays
(#1206)
### Rationale for this change
Reading one field from a variant column today reassembles the whole
value per row (`VariantArray.Value`) and then navigates to the field in
Go. When the variant is shredded, that field is often already a typed
column, so the full reassembly is wasted work.
### What changes are included in this PR?
- Adds `compute.VariantGet(ctx, *extensions.VariantArray,
VariantGetOptions{Path, AsType, Strict})`, mirroring the arrow-rs
[variant_get](https://github.com/apache/arrow-rs/blob/main/parquet-variant-compute/src/variant_get.rs).
It follows the shredded `typed_value` columns as far as the path allows
(stepping into struct fields directly, gathering list elements with the
`take` kernel) and reassembles the residual `value` per-row only for
what remains.
- `AsType == nil` returns a `VariantArray` pointing at the path; set it
to get a typed array. Typed output is produced by grouping leaves by
their natural Arrow type and casting each group with the existing
`compute` cast kernels, so per-element values convert to the requested
target independent of row order.
- `Strict` controls cast strictness: the default allows
overflow/truncation via the cast kernels, `Strict` makes a lossy or
impossible cast error (arrow-go has no per-value null-on-failure mode).
- Adds `variant.VariantPath` (an opaque
`Field`/`Index`/`Join`/`Len`/`StepAt` builder) and
`variant.Value.GetByPath`, plus a `VariantArray.VariantType()` accessor.
### Follow-ups (out of scope here):
- Nested `AsType` output: struct/list target types return
`arrow.ErrNotImplemented`; materializing them would need a recursive
per-field builder.
### Notes on cross-implementation behavior
Path navigation follows arrow-rs rather than Spark's `variant_get` in
two places: a field access on a non-object errors (Spark returns null),
and `Strict` treats in-range fractional truncation as an error (Spark
truncates). Absent paths, out-of-range indices, and
object/array-to-primitive casts match Spark (null, or error under
`Strict`).
### Are these changes tested?
- `arrow/compute/variant_get_test.go` covers typed and variant output,
nested field and list-index paths, residual/mixed-shredded rows, missing
field, null rows, dictionary-encoded metadata, mixed-width/type leaves,
order independence, the perfect-shredding fast path, `Strict` vs default
cast outcomes, nested-type rejection, field-on-scalar errors, and
`CheckedAllocator` leak checks.
- `parquet/variant/path_test.go` covers the `VariantPath` builder and
`GetByPath` navigation, including the empty-string object key.
### Are there any user-facing changes?
Yes - new exported API: `compute.VariantGet`,
`compute.VariantGetOptions`, `variant.VariantPath`,
`variant.Value.GetByPath`, and `extensions.VariantArray.VariantType()`.
Additive only.
---
arrow/compute/variant_get.go | 750 ++++++++++++++++++++++++++++++++
arrow/compute/variant_get_test.go | 875 ++++++++++++++++++++++++++++++++++++++
arrow/extensions/variant.go | 10 +
parquet/variant/path.go | 109 +++++
parquet/variant/path_test.go | 116 +++++
5 files changed, 1860 insertions(+)
diff --git a/arrow/compute/variant_get.go b/arrow/compute/variant_get.go
new file mode 100644
index 00000000..8f5a2e2a
--- /dev/null
+++ b/arrow/compute/variant_get.go
@@ -0,0 +1,750 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package compute
+
+import (
+ "context"
+ "fmt"
+
+ "github.com/apache/arrow-go/v18/arrow"
+ "github.com/apache/arrow-go/v18/arrow/array"
+ "github.com/apache/arrow-go/v18/arrow/bitutil"
+ "github.com/apache/arrow-go/v18/arrow/decimal"
+ "github.com/apache/arrow-go/v18/arrow/decimal128"
+ "github.com/apache/arrow-go/v18/arrow/extensions"
+ "github.com/apache/arrow-go/v18/arrow/memory"
+ "github.com/apache/arrow-go/v18/parquet/variant"
+ "github.com/google/uuid"
+)
+
+// VariantGetOptions controls VariantGet.
+type VariantGetOptions struct {
+ // Path is the path to extract from every variant value.
+ Path variant.VariantPath
+ // AsType, when nil, makes VariantGet return a VariantArray pointing at
the path;
+ // when set, the extracted values are cast to it via the cast kernels.
+ AsType arrow.DataType
+ // Strict makes a lossy cast fail; otherwise a value that cannot
convert to AsType
+ // nulls only that row, not the rest of its natural-type group.
+ Strict bool
+}
+
+// VariantGet extracts opts.Path from every value of input. It follows the
shredded
+// typed_value columns as far as the path allows - stepping into struct fields
+// directly and gathering list elements with the take kernel - then
reassembles only
+// the residual for any remaining path. With AsType nil it returns a
VariantArray of
+// the extracted values; otherwise it casts them to AsType with the cast
kernels.
+func VariantGet(ctx context.Context, input *extensions.VariantArray, opts
VariantGetOptions) (arrow.Array, error) {
+ if input == nil {
+ return nil, fmt.Errorf("%w: VariantGet requires a non-nil
VariantArray", arrow.ErrInvalid)
+ }
+
+ // Reject nested target storage. Unwrap extension types first: they
embed
+ // ExtensionBase and so satisfy arrow.NestedType even when backed by
e.g. UUID.
+ nestedCheck := opts.AsType
+ if ext, ok := nestedCheck.(arrow.ExtensionType); ok {
+ nestedCheck = ext.StorageType()
+ }
+ if _, ok := nestedCheck.(arrow.NestedType); ok {
+ return nil, fmt.Errorf("%w: VariantGet cast to nested type %s",
arrow.ErrNotImplemented, opts.AsType)
+ }
+
+ // Empty path, no cast: the values are returned unchanged.
+ if opts.Path.Len() == 0 && opts.AsType == nil {
+ input.Retain()
+
+ return input, nil
+ }
+
+ return shreddedGetPath(ctx, input, opts)
+}
+
+// shreddingState is a (value?, typed_value?) column pair at one level of a
shredded
+// variant, mirroring arrow-rs ShreddingState.
+type shreddingState struct {
+ value arrow.TypedArray[[]byte]
+ typedValue arrow.Array
+ length int
+}
+
+func stateFromInput(input *extensions.VariantArray) shreddingState {
+ return shreddingState{
+ value: input.UntypedValues(),
+ typedValue: input.Shredded(),
+ length: input.Len(),
+ }
+}
+
+func stateFromFieldStruct(child *array.Struct) shreddingState {
+ ct := child.DataType().(*arrow.StructType)
+
+ var value arrow.TypedArray[[]byte]
+ if idx, ok := ct.FieldIdx("value"); ok {
+ value = child.Field(idx).(arrow.TypedArray[[]byte])
+ }
+
+ var typed arrow.Array
+ if idx, ok := ct.FieldIdx("typed_value"); ok {
+ typed = child.Field(idx)
+ }
+
+ return shreddingState{value: value, typedValue: typed, length:
child.Len()}
+}
+
+type pathStepKind int
+
+const (
+ stepSuccess pathStepKind = iota
+ stepMissing
+)
+
+type pathStep struct {
+ kind pathStepKind
+ state shreddingState
+ owned []arrow.Array // intermediate take results the caller must release
+}
+
+// missingStep marks a path step whose typed field is absent. The descent loop
breaks
+// on any residual before stepping, so a step that reaches here is provably
missing.
+func (s shreddingState) missingStep() pathStep {
+ return pathStep{kind: stepMissing}
+}
+
+// hasResidual reports whether any row carries a value in this level's value
column.
+func (s shreddingState) hasResidual() bool {
+ return s.value != nil && s.value.NullN() != s.value.Len()
+}
+
+func fieldStep(s shreddingState, name string) (pathStep, error) {
+ if s.typedValue == nil {
+ return s.missingStep(), nil
+ }
+ st, ok := s.typedValue.(*array.Struct)
+ if !ok {
+ // A field step into a non-object shredded value is a type
error, matching the
+ // per-row GetByPath path. Any residual was already diverted
before this runs.
+ return pathStep{}, fmt.Errorf("%w: variant path field %q
applied to non-object %s",
+ arrow.ErrInvalid, name, s.typedValue.DataType())
+ }
+ idx, ok := st.DataType().(*arrow.StructType).FieldIdx(name)
+ if !ok {
+ return s.missingStep(), nil
+ }
+ child, ok := st.Field(idx).(*array.Struct)
+ if !ok {
+ return pathStep{}, fmt.Errorf("%w: expected struct field %q
while following path, got %s",
+ arrow.ErrInvalid, name, st.Field(idx).DataType())
+ }
+
+ return pathStep{kind: stepSuccess, state: stateFromFieldStruct(child)},
nil
+}
+
+// indexStep gathers element index from every row of a shredded list with the
take
+// kernel, producing the shredding state one level deeper.
+func indexStep(ctx context.Context, mem memory.Allocator, s shreddingState,
index int) (pathStep, error) {
+ if s.typedValue == nil {
+ return s.missingStep(), nil
+ }
+ list, ok := s.typedValue.(array.ListLike)
+ if !ok {
+ return s.missingStep(), nil
+ }
+ elems, ok := list.ListValues().(*array.Struct)
+ if !ok {
+ return s.missingStep(), nil
+ }
+
+ ib := array.NewUint64Builder(mem)
+ defer ib.Release()
+ ib.Reserve(s.length)
+ for row := 0; row < s.length; row++ {
+ start, end := list.ValueOffsets(row)
+ if list.IsValid(row) && index >= 0 && int64(index) < end-start {
+ ib.Append(uint64(start + int64(index)))
+ } else {
+ ib.AppendNull()
+ }
+ }
+ indices := ib.NewArray()
+ defer indices.Release()
+
+ et := elems.DataType().(*arrow.StructType)
+ var owned []arrow.Array
+ var next shreddingState
+ next.length = s.length
+
+ if vi, ok := et.FieldIdx("value"); ok {
+ taken, err := TakeArray(ctx, elems.Field(vi), indices)
+ if err != nil {
+ return pathStep{}, err
+ }
+ owned = append(owned, taken)
+ next.value = taken.(arrow.TypedArray[[]byte])
+ }
+ if ti, ok := et.FieldIdx("typed_value"); ok {
+ taken, err := TakeArray(ctx, elems.Field(ti), indices)
+ if err != nil {
+ releaseAll(owned)
+
+ return pathStep{}, err
+ }
+ owned = append(owned, taken)
+ next.typedValue = taken
+ }
+
+ return pathStep{kind: stepSuccess, state: next, owned: owned}, nil
+}
+
+func releaseAll(arrs []arrow.Array) {
+ for _, a := range arrs {
+ a.Release()
+ }
+}
+
+func shreddedGetPath(ctx context.Context, input *extensions.VariantArray, opts
VariantGetOptions) (arrow.Array, error) {
+ mem := GetAllocator(ctx)
+ state := stateFromInput(input)
+ nulls := newNullTracker(input.Len(), mem)
+ defer nulls.release()
+ nulls.merge(input.Storage())
+
+ var owned []arrow.Array
+ defer func() { releaseAll(owned) }()
+
+ idx := 0
+ for idx < opts.Path.Len() {
+ // residual-backed rows live in the value column, unreachable
by the typed_value descent; reassemble per-row.
+ if state.hasResidual() {
+ break
+ }
+
+ name, index, isField := opts.Path.StepAt(idx)
+ var (
+ step pathStep
+ err error
+ )
+ if isField {
+ step, err = fieldStep(state, name)
+ } else {
+ step, err = indexStep(ctx, mem, state, index)
+ }
+ if err != nil {
+ return nil, err
+ }
+
+ if step.kind == stepSuccess {
+ nulls.merge(state.typedValue)
+ state = step.state
+ owned = append(owned, step.owned...)
+ idx++
+
+ continue
+ }
+
+ // stepMissing: the typed field is provably absent (no
residual, checked above).
+ return allNullResult(mem, input.Len(), opts.AsType), nil
+ }
+
+ remaining := subPath(opts.Path, idx)
+
+ // Try to return the typed column directly before building the target
array,
+ // so a perfect shredding does not allocate a struct and bitmap it
discards.
+ if remaining.Len() == 0 && opts.AsType != nil {
+ if col := perfectShredded(state, nulls, opts.AsType); col !=
nil {
+ defer col.Release()
+
+ return CastArray(ctx, col, NewCastOptions(opts.AsType,
opts.Strict))
+ }
+ }
+
+ target, err := buildTargetVariant(input, state, nulls, mem)
+ if err != nil {
+ return nil, err
+ }
+ defer target.Release()
+
+ if remaining.Len() == 0 && opts.AsType == nil {
+ target.Retain()
+
+ return target, nil
+ }
+
+ leaves, err := extractLeaves(target, remaining)
+ if err != nil {
+ return nil, err
+ }
+ if opts.AsType == nil {
+ return buildLeafVariantArray(mem, leaves), nil
+ }
+
+ return castLeaves(ctx, mem, leaves, opts.AsType, opts.Strict)
+}
+
+// perfectShredded returns the typed_value column when the path landed on a
fully
+// shredded value of exactly AsType and no ancestor nulls need merging;
otherwise
+// the caller's reassembly path produces the same values.
+func perfectShredded(s shreddingState, nulls *nullTracker, asType
arrow.DataType) arrow.Array {
+ if s.typedValue == nil || !nulls.allValid() {
+ return nil
+ }
+ if !arrow.TypeEqual(s.typedValue.DataType(), asType) {
+ return nil
+ }
+ if s.value != nil && s.value.NullN() != s.value.Len() {
+ return nil
+ }
+
+ s.typedValue.Retain()
+
+ return s.typedValue
+}
+
+func buildTargetVariant(input *extensions.VariantArray, s shreddingState,
nulls *nullTracker, mem memory.Allocator) (*extensions.VariantArray, error) {
+ // Read the raw metadata column rather than input.Metadata(), which
asserts plain
+ // binary and panics on dictionary-encoded metadata; the raw column
preserves
+ // dictionary/large-binary encoding and is decoded by the target's own
reader.
+ storage := input.Storage().(*array.Struct)
+ mdIdx, ok := storage.DataType().(*arrow.StructType).FieldIdx("metadata")
+ if !ok {
+ return nil, fmt.Errorf("%w: variant storage is missing its
metadata field", arrow.ErrInvalid)
+ }
+ metadata := storage.Field(mdIdx)
+
+ fields := []arrow.Field{{Name: "metadata", Type: metadata.DataType(),
Nullable: false}}
+ cols := []arrow.Array{metadata}
+ if s.value != nil {
+ fields = append(fields, arrow.Field{Name: "value", Type:
s.value.DataType(), Nullable: true})
+ cols = append(cols, s.value)
+ }
+ if s.typedValue != nil {
+ fields = append(fields, arrow.Field{Name: "typed_value", Type:
s.typedValue.DataType(), Nullable: true})
+ cols = append(cols, s.typedValue)
+ }
+
+ bitmap, nullCount := nulls.validityBitmap()
+ st, err := array.NewStructArrayWithFieldsAndNulls(cols, fields, bitmap,
nullCount, 0)
+ if err != nil {
+ return nil, err
+ }
+ defer st.Release()
+
+ vt, err := extensions.NewVariantType(st.DataType())
+ if err != nil {
+ return nil, err
+ }
+
+ return array.NewExtensionArrayWithStorage(vt,
st).(*extensions.VariantArray), nil
+}
+
+// subPath returns the suffix of p starting at from, rebuilt through the
opaque API.
+func subPath(p variant.VariantPath, from int) variant.VariantPath {
+ var out variant.VariantPath
+ for i := from; i < p.Len(); i++ {
+ if name, index, isField := p.StepAt(i); isField {
+ out = out.Field(name)
+ } else {
+ out = out.Index(index)
+ }
+ }
+
+ return out
+}
+
+// variantLeaf is one row's extracted value; present is false when the path is
+// absent for that row (or the row is null).
+type variantLeaf struct {
+ value variant.Value
+ present bool
+}
+
+func extractLeaves(target *extensions.VariantArray, path variant.VariantPath)
([]variantLeaf, error) {
+ leaves := make([]variantLeaf, target.Len())
+ for i := range leaves {
+ if target.IsNull(i) {
+ continue
+ }
+ v, err := target.Value(i)
+ if err != nil {
+ return nil, fmt.Errorf("variant: reassembling row %d:
%w", i, err)
+ }
+ leaf, found, err := v.GetByPath(path)
+ if err != nil {
+ return nil, err
+ }
+ leaves[i] = variantLeaf{value: leaf, present: found}
+ }
+
+ return leaves, nil
+}
+
+func buildLeafVariantArray(mem memory.Allocator, leaves []variantLeaf)
arrow.Array {
+ bldr := extensions.NewVariantBuilder(mem,
extensions.NewDefaultVariantType())
+ defer bldr.Release()
+ bldr.Reserve(len(leaves))
+ for _, l := range leaves {
+ if !l.present {
+ bldr.AppendNull()
+
+ continue
+ }
+ bldr.Append(l.value)
+ }
+
+ return bldr.NewArray()
+}
+
+// castLeaves converts each leaf to asType (arrow-rs variant_get parity):
leaves are
+// grouped by natural type, each group cast with the cast kernels, then
scattered back
+// so the result is order-independent. Strict errors on a lossy cast, else
null.
+func castLeaves(ctx context.Context, mem memory.Allocator, leaves
[]variantLeaf, asType arrow.DataType, strict bool) (arrow.Array, error) {
+ type leafGroup struct {
+ dt arrow.DataType
+ rows []int
+ }
+ groups := make(map[string]*leafGroup)
+ var order []string
+ for i, l := range leaves {
+ if !l.present || l.value.Type() == variant.Null {
+ continue
+ }
+ dt := naturalArrowType(l.value)
+ if dt == nil {
+ // Object/array leaves have no primitive natural type.
Under Strict this is an
+ // impossible cast (errors like any other); otherwise
the row stays null.
+ if strict {
+ return nil, fmt.Errorf("%w: cannot cast
non-primitive variant leaf to %s", arrow.ErrInvalid, asType)
+ }
+
+ continue
+ }
+ key := dt.String()
+ g := groups[key]
+ if g == nil {
+ g = &leafGroup{dt: dt}
+ groups[key] = g
+ order = append(order, key)
+ }
+ g.rows = append(g.rows, i)
+ }
+
+ perm := make([]uint64, len(leaves))
+ valid := make([]bool, len(leaves))
+ var casted []arrow.Array
+ defer func() { releaseAll(casted) }()
+
+ var pos uint64
+ for _, key := range order {
+ g := groups[key]
+ col := buildTypedColumn(mem, g.dt, leaves, g.rows)
+ cast, err := CastArray(ctx, col, NewCastOptions(asType, strict))
+ col.Release()
+ if err == nil {
+ casted = append(casted, cast)
+ for _, row := range g.rows {
+ perm[row] = pos
+ valid[row] = true
+ pos++
+ }
+
+ continue
+ }
+ if strict {
+ return nil, err
+ }
+ // Non-strict: retry each row alone so only the inconvertible
rows null, not the whole group.
+ for _, row := range g.rows {
+ rc := buildTypedColumn(mem, g.dt, leaves, []int{row})
+ one, cerr := CastArray(ctx, rc, NewCastOptions(asType,
strict))
+ rc.Release()
+ if cerr != nil {
+ continue // this row alone is inconvertible; it
stays null
+ }
+ casted = append(casted, one)
+ perm[row] = pos
+ valid[row] = true
+ pos++
+ }
+ }
+
+ if len(casted) == 0 {
+ return allNullResult(mem, len(leaves), asType), nil
+ }
+
+ // One natural type covering every row already sits in original order.
+ if len(casted) == 1 && pos == uint64(len(leaves)) {
+ casted[0].Retain()
+
+ return casted[0], nil
+ }
+
+ combined, err := array.Concatenate(casted, mem)
+ if err != nil {
+ return nil, err
+ }
+ defer combined.Release()
+
+ ib := array.NewUint64Builder(mem)
+ defer ib.Release()
+ ib.AppendValues(perm, valid)
+ indices := ib.NewArray()
+ defer indices.Release()
+
+ return TakeArray(ctx, combined, indices)
+}
+
+// buildTypedColumn materializes the given leaf rows, all of natural type dt,
into a
+// homogeneous Arrow array the cast kernels can consume.
+func buildTypedColumn(mem memory.Allocator, dt arrow.DataType, leaves
[]variantLeaf, rows []int) arrow.Array {
+ bldr := array.NewBuilder(mem, dt)
+ defer bldr.Release()
+ bldr.Reserve(len(rows))
+ for _, row := range rows {
+ if !appendNatural(bldr, leaves[row].value) {
+ bldr.AppendNull()
+ }
+ }
+
+ return bldr.NewArray()
+}
+
+// allNullResult builds the all-null output for a provably missing path.
+func allNullResult(mem memory.Allocator, n int, asType arrow.DataType)
arrow.Array {
+ if asType != nil {
+ return array.MakeArrayOfNull(mem, asType, n)
+ }
+
+ // MakeArrayOfNull cannot build the variant extension type (its storage
struct's
+ // metadata/value are non-nullable), so append encoded variant nulls
instead.
+ bldr := extensions.NewVariantBuilder(mem,
extensions.NewDefaultVariantType())
+ defer bldr.Release()
+ for range n {
+ bldr.AppendNull()
+ }
+
+ return bldr.NewArray()
+}
+
+// nullTracker accumulates ancestor validity bitmaps with a bitmap AND.
+type nullTracker struct {
+ length int
+ mem memory.Allocator
+ buf *memory.Buffer // validity bitmap (1 = valid); nil means all
valid
+}
+
+func newNullTracker(length int, mem memory.Allocator) *nullTracker {
+ return &nullTracker{length: length, mem: mem}
+}
+
+// merge folds arr's validity into the accumulated mask. Arrow validity bits
are
+// 1=valid, so accumulating ancestor nulls is a bitmap AND (a row is null in
the
+// result when it is null at any level) - the validity-space equivalent of
OR-ing
+// null masks.
+func (n *nullTracker) merge(arr arrow.Array) {
+ if arr == nil {
+ return
+ }
+ vb := arr.Data().Buffers()[0]
+ if vb == nil {
+ return // all valid
+ }
+ off := int64(arr.Data().Offset())
+ if n.buf == nil {
+ n.buf = bitutil.BitmapAndAlloc(n.mem, vb.Bytes(), vb.Bytes(),
off, off, int64(n.length), 0)
+
+ return
+ }
+ merged := bitutil.BitmapAndAlloc(n.mem, n.buf.Bytes(), vb.Bytes(), 0,
off, int64(n.length), 0)
+ n.buf.Release()
+ n.buf = merged
+}
+
+func (n *nullTracker) allValid() bool { return n.buf == nil }
+
+func (n *nullTracker) validityBitmap() (*memory.Buffer, int) {
+ if n.buf == nil {
+ return nil, 0
+ }
+
+ return n.buf, n.length - bitutil.CountSetBits(n.buf.Bytes(), 0,
n.length)
+}
+
+func (n *nullTracker) release() {
+ if n.buf != nil {
+ n.buf.Release()
+ n.buf = nil
+ }
+}
+
+func naturalArrowType(v variant.Value) arrow.DataType {
+ switch v.Type() {
+ case variant.Bool:
+ return arrow.FixedWidthTypes.Boolean
+ case variant.Int8:
+ return arrow.PrimitiveTypes.Int8
+ case variant.Int16:
+ return arrow.PrimitiveTypes.Int16
+ case variant.Int32:
+ return arrow.PrimitiveTypes.Int32
+ case variant.Int64:
+ return arrow.PrimitiveTypes.Int64
+ case variant.Float:
+ return arrow.PrimitiveTypes.Float32
+ case variant.Double:
+ return arrow.PrimitiveTypes.Float64
+ case variant.String:
+ return arrow.BinaryTypes.String
+ case variant.Binary:
+ return arrow.BinaryTypes.Binary
+ case variant.Date:
+ return arrow.FixedWidthTypes.Date32
+ case variant.Time:
+ return arrow.FixedWidthTypes.Time64us
+ case variant.TimestampMicros:
+ return &arrow.TimestampType{Unit: arrow.Microsecond, TimeZone:
"UTC"}
+ case variant.TimestampMicrosNTZ:
+ return &arrow.TimestampType{Unit: arrow.Microsecond}
+ case variant.TimestampNanos:
+ return &arrow.TimestampType{Unit: arrow.Nanosecond, TimeZone:
"UTC"}
+ case variant.TimestampNanosNTZ:
+ return &arrow.TimestampType{Unit: arrow.Nanosecond}
+ case variant.UUID:
+ return extensions.NewUUIDType()
+ case variant.Decimal4, variant.Decimal8, variant.Decimal16:
+ return &arrow.Decimal128Type{Precision: 38, Scale:
int32(decimalScale(v))}
+ }
+
+ return nil
+}
+
+// appendNatural appends v to bldr when v's value matches bldr's element type,
+// reporting whether it did; callers group leaves by natural type first, so it
matches.
+func appendNatural(bldr array.Builder, v variant.Value) bool {
+ switch b := bldr.(type) {
+ case *array.BooleanBuilder:
+ if x, ok := v.Value().(bool); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Int8Builder:
+ if x, ok := v.Value().(int8); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Int16Builder:
+ if x, ok := v.Value().(int16); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Int32Builder:
+ if x, ok := v.Value().(int32); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Int64Builder:
+ if x, ok := v.Value().(int64); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Float32Builder:
+ if x, ok := v.Value().(float32); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Float64Builder:
+ if x, ok := v.Value().(float64); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.StringBuilder:
+ if x, ok := v.Value().(string); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.BinaryBuilder:
+ if x, ok := v.Value().([]byte); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Date32Builder:
+ if x, ok := v.Value().(arrow.Date32); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Time64Builder:
+ if x, ok := v.Value().(arrow.Time64); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.TimestampBuilder:
+ if x, ok := v.Value().(arrow.Timestamp); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *extensions.UUIDBuilder:
+ if x, ok := v.Value().(uuid.UUID); ok {
+ b.Append(x)
+
+ return true
+ }
+ case *array.Decimal128Builder:
+ if num, ok := decimalAsNum128(v); ok && int32(decimalScale(v))
== b.Type().(*arrow.Decimal128Type).Scale {
+ b.Append(num)
+
+ return true
+ }
+ }
+
+ return false
+}
+
+func decimalScale(v variant.Value) uint8 {
+ switch d := v.Value().(type) {
+ case variant.DecimalValue[decimal.Decimal32]:
+ return d.Scale
+ case variant.DecimalValue[decimal.Decimal64]:
+ return d.Scale
+ case variant.DecimalValue[decimal.Decimal128]:
+ return d.Scale
+ }
+
+ return 0
+}
+
+func decimalAsNum128(v variant.Value) (decimal128.Num, bool) {
+ switch d := v.Value().(type) {
+ case variant.DecimalValue[decimal.Decimal32]:
+ return decimal128.FromI64(int64(d.Value.(decimal.Decimal32))),
true
+ case variant.DecimalValue[decimal.Decimal64]:
+ return decimal128.FromI64(int64(d.Value.(decimal.Decimal64))),
true
+ case variant.DecimalValue[decimal.Decimal128]:
+ return d.Value.(decimal.Decimal128), true
+ }
+
+ return decimal128.Num{}, false
+}
diff --git a/arrow/compute/variant_get_test.go
b/arrow/compute/variant_get_test.go
new file mode 100644
index 00000000..cf841ba2
--- /dev/null
+++ b/arrow/compute/variant_get_test.go
@@ -0,0 +1,875 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package compute_test
+
+import (
+ "context"
+ "testing"
+
+ "github.com/apache/arrow-go/v18/arrow"
+ "github.com/apache/arrow-go/v18/arrow/array"
+ "github.com/apache/arrow-go/v18/arrow/compute"
+ "github.com/apache/arrow-go/v18/arrow/compute/exec"
+ "github.com/apache/arrow-go/v18/arrow/decimal"
+ "github.com/apache/arrow-go/v18/arrow/extensions"
+ "github.com/apache/arrow-go/v18/arrow/memory"
+ "github.com/apache/arrow-go/v18/parquet/variant"
+ "github.com/google/uuid"
+ "github.com/stretchr/testify/assert"
+ "github.com/stretchr/testify/require"
+)
+
+func vgVariant(t *testing.T, v any) variant.Value {
+ t.Helper()
+ var b variant.Builder
+ require.NoError(t, b.Append(v))
+ val, err := b.Build()
+ require.NoError(t, err)
+
+ return val
+}
+
+func vgNonShredded(t *testing.T, mem memory.Allocator, vals ...any)
*extensions.VariantArray {
+ t.Helper()
+ bldr := extensions.NewVariantBuilder(mem,
extensions.NewDefaultVariantType())
+ defer bldr.Release()
+ for _, v := range vals {
+ if v == nil {
+ bldr.AppendNull()
+
+ continue
+ }
+ bldr.Append(vgVariant(t, v))
+ }
+
+ return bldr.NewArray().(*extensions.VariantArray)
+}
+
+func vgShreddedInt(t *testing.T, mem memory.Allocator, vals ...int64)
*extensions.VariantArray {
+ t.Helper()
+ vt := extensions.NewShreddedVariantType(arrow.PrimitiveTypes.Int64)
+ bldr := extensions.NewVariantBuilder(mem, vt)
+ defer bldr.Release()
+ for _, v := range vals {
+ bldr.Append(vgVariant(t, v))
+ }
+
+ return bldr.NewArray().(*extensions.VariantArray)
+}
+
+func field(name string) variant.VariantPath { return
variant.VariantPath{}.Field(name) }
+
+func TestVariantGetTyped(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem,
+ map[string]any{"a": int64(1)},
+ map[string]any{"a": int64(2)},
+ nil,
+ )
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a"), AsType: arrow.PrimitiveTypes.Int64})
+ require.NoError(t, err)
+ defer out.Release()
+
+ ints := out.(*array.Int64)
+ require.Equal(t, 3, ints.Len())
+ assert.EqualValues(t, 1, ints.Value(0))
+ assert.EqualValues(t, 2, ints.Value(1))
+ assert.True(t, ints.IsNull(2))
+}
+
+func TestVariantGetVariantOutput(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, map[string]any{"a": int64(7)},
map[string]any{"b": int64(9)})
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a")})
+ require.NoError(t, err)
+ defer out.Release()
+
+ varr := out.(*extensions.VariantArray)
+ v, err := varr.Value(0)
+ require.NoError(t, err)
+ assert.EqualValues(t, 7, v.Value())
+ assert.True(t, varr.IsNull(1))
+}
+
+func TestVariantGetNestedAndIndex(t *testing.T) {
+ mem := memory.DefaultAllocator
+ nested := vgNonShredded(t, mem, map[string]any{"a": map[string]any{"b":
int64(5)}})
+ defer nested.Release()
+ out, err := compute.VariantGet(context.Background(), nested,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Field("a").Field("b"), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ assert.EqualValues(t, 5, out.(*array.Int64).Value(0))
+
+ arrs := vgNonShredded(t, mem, []any{int64(10), int64(20), int64(30)})
+ defer arrs.Release()
+ got, err := compute.VariantGet(context.Background(), arrs,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(1), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer got.Release()
+ assert.EqualValues(t, 20, got.(*array.Int64).Value(0))
+
+ oob, err := compute.VariantGet(context.Background(), arrs,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(9), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer oob.Release()
+ assert.True(t, oob.(*array.Int64).IsNull(0))
+}
+
+// TestVariantGetMixedShreddedRows reproduces zeroshade's [1,2] case: row 0 is
in
+// typed_value, row 1 is in the residual value. Both must come back, not
[1,null].
+func TestVariantGetMixedShreddedRows(t *testing.T) {
+ mem := memory.DefaultAllocator
+ s := arrow.StructOf(
+ arrow.Field{Name: "metadata", Type: arrow.BinaryTypes.Binary},
+ arrow.Field{Name: "value", Type: arrow.BinaryTypes.Binary,
Nullable: true},
+ arrow.Field{Name: "typed_value", Type:
arrow.PrimitiveTypes.Int64, Nullable: true})
+ b := array.NewStructBuilder(mem, s)
+ defer b.Release()
+ mb := b.FieldBuilder(0).(*array.BinaryBuilder)
+ vb := b.FieldBuilder(1).(*array.BinaryBuilder)
+ tb := b.FieldBuilder(2).(*array.Int64Builder)
+
+ b.Append(true)
+ mb.Append(variant.EmptyMetadataBytes[:])
+ vb.AppendNull()
+ tb.Append(1)
+
+ b.Append(true)
+ mb.Append(variant.EmptyMetadataBytes[:])
+ enc, err := variant.Encode(int64(2))
+ require.NoError(t, err)
+ vb.Append(enc)
+ tb.AppendNull()
+
+ st := b.NewArray()
+ defer st.Release()
+ vt, err := extensions.NewVariantType(s)
+ require.NoError(t, err)
+ arr := array.NewExtensionArrayWithStorage(vt,
st).(*extensions.VariantArray)
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Int64})
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ require.Equal(t, 2, ints.Len())
+ assert.EqualValues(t, 1, ints.Value(0))
+ assert.EqualValues(t, 2, ints.Value(1), "residual-value row must be
reconstructed, not null")
+ assert.False(t, ints.IsNull(1))
+}
+
+// TestVariantGetLenientCast covers zeroshade's :269 examples: ordinary
widening
+// casts succeed under the default (non-strict) mode.
+func TestVariantGetLenientCast(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgShreddedInt(t, mem, 3, 5)
+ defer arr.Release()
+
+ f64, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Float64})
+ require.NoError(t, err)
+ defer f64.Release()
+ assert.EqualValues(t, 3, f64.(*array.Float64).Value(0))
+ assert.EqualValues(t, 5, f64.(*array.Float64).Value(1))
+
+ dec, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{AsType: &arrow.Decimal128Type{Precision: 10, Scale:
0}})
+ require.NoError(t, err)
+ defer dec.Release()
+ assert.Equal(t, 2, dec.Len())
+}
+
+func TestVariantGetStrictCastErrors(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgShreddedInt(t, mem, 5_000_000_000) // overflows int8
+ defer arr.Release()
+
+ _, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ AsType: arrow.PrimitiveTypes.Int8, Strict: true,
+ })
+ require.Error(t, err, "strict cast of an overflowing value must error")
+}
+
+// TestVariantGetFieldOnScalarErrors covers :323: a field step into a scalar
is a
+// type error, not a silent null.
+func TestVariantGetFieldOnScalarErrors(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, int64(1))
+ defer arr.Release()
+
+ _, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a")})
+ require.ErrorIs(t, err, arrow.ErrInvalid)
+}
+
+// TestVariantGetHugeIndex covers :307: a huge index must not wrap to a valid
one.
+func TestVariantGetHugeIndex(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, []any{int64(10), int64(20)})
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(1 << 40), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ assert.True(t, out.(*array.Int64).IsNull(0))
+}
+
+func TestVariantGetEmptyPath(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, int64(1), int64(2))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{})
+ require.NoError(t, err)
+ defer out.Release()
+ assert.Equal(t, 2, out.Len())
+}
+
+// TestVariantGetShreddedFieldPushdown drives nested field steps through the
shredded
+// typed_value columns and the perfect-shredding fast path.
+func TestVariantGetShreddedFieldPushdown(t *testing.T) {
+ mem := memory.DefaultAllocator
+ vt := extensions.NewShreddedVariantType(arrow.StructOf(
+ arrow.Field{Name: "a", Type: arrow.StructOf(
+ arrow.Field{Name: "b", Type:
arrow.PrimitiveTypes.Int64})}))
+ bldr := extensions.NewVariantBuilder(mem, vt)
+ defer bldr.Release()
+ bldr.Append(vgVariant(t, map[string]any{"a": map[string]any{"b":
int64(5)}}))
+ bldr.Append(vgVariant(t, map[string]any{"a": map[string]any{"b":
int64(6)}}))
+ arr := bldr.NewArray().(*extensions.VariantArray)
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Field("a").Field("b"), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ assert.EqualValues(t, 5, ints.Value(0))
+ assert.EqualValues(t, 6, ints.Value(1))
+}
+
+// TestVariantGetShreddedListIndex drives an index step over a shredded list,
which
+// gathers elements with the take kernel.
+func TestVariantGetShreddedListIndex(t *testing.T) {
+ mem := memory.DefaultAllocator
+ vt :=
extensions.NewShreddedVariantType(arrow.ListOf(arrow.PrimitiveTypes.Int64))
+ bldr := extensions.NewVariantBuilder(mem, vt)
+ defer bldr.Release()
+ bldr.Append(vgVariant(t, []any{int64(10), int64(20), int64(30)}))
+ bldr.Append(vgVariant(t, []any{int64(40), int64(50)}))
+ arr := bldr.NewArray().(*extensions.VariantArray)
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(1), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ assert.EqualValues(t, 20, ints.Value(0))
+ assert.EqualValues(t, 50, ints.Value(1))
+}
+
+func TestVariantGetNoLeak(t *testing.T) {
+ mem := memory.NewCheckedAllocator(memory.DefaultAllocator)
+ defer mem.AssertSize(t, 0)
+ ctx := exec.WithAllocator(context.Background(), mem)
+
+ vt :=
extensions.NewShreddedVariantType(arrow.ListOf(arrow.PrimitiveTypes.Int64))
+ bldr := extensions.NewVariantBuilder(mem, vt)
+ bldr.Append(vgVariant(t, []any{int64(10), int64(20)}))
+ bldr.AppendNull()
+ arr := bldr.NewArray().(*extensions.VariantArray)
+ bldr.Release()
+
+ idx, err := compute.VariantGet(ctx, arr, compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(0), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ idx.Release()
+ arr.Release()
+
+ // A missing field on an object-shredded variant exercises the all-null
path.
+ objVT :=
extensions.NewShreddedVariantType(arrow.StructOf(arrow.Field{Name: "a", Type:
arrow.PrimitiveTypes.Int64}))
+ ob := extensions.NewVariantBuilder(mem, objVT)
+ ob.Append(vgVariant(t, map[string]any{"a": int64(1)}))
+ objArr := ob.NewArray().(*extensions.VariantArray)
+ ob.Release()
+
+ missing, err := compute.VariantGet(ctx, objArr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Field("nope"), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ missing.Release()
+ objArr.Release()
+}
+
+// TestVariantGetDictMetadata guards against a panic when the metadata column
is
+// dictionary-encoded (spec-legal): buildTargetVariant must read the raw
column,
+// not the plain-binary accessor.
+func TestVariantGetDictMetadata(t *testing.T) {
+ mem := memory.DefaultAllocator
+ s := arrow.StructOf(
+ arrow.Field{Name: "metadata", Type:
&arrow.DictionaryType{IndexType: arrow.PrimitiveTypes.Uint8, ValueType:
arrow.BinaryTypes.Binary}},
+ arrow.Field{Name: "value", Type: arrow.BinaryTypes.Binary,
Nullable: true},
+ arrow.Field{Name: "typed_value", Type: arrow.StructOf(
+ arrow.Field{Name: "a", Type: arrow.StructOf(
+ arrow.Field{Name: "value", Type:
arrow.BinaryTypes.Binary, Nullable: true},
+ arrow.Field{Name: "typed_value", Type:
arrow.PrimitiveTypes.Int64, Nullable: true},
+ )},
+ ), Nullable: true})
+ vt, err := extensions.NewVariantType(s)
+ require.NoError(t, err)
+ bldr := vt.NewBuilder(mem).(*extensions.VariantBuilder)
+ defer bldr.Release()
+ bldr.Append(vgVariant(t, map[string]any{"a": int64(5), "b": "resid"}))
+ arr := bldr.NewArray().(*extensions.VariantArray)
+ defer arr.Release()
+
+ // "b" is not shredded, so this takes the NotShredded ->
buildTargetVariant path.
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: variant.VariantPath{}.Field("b")})
+ require.NoError(t, err)
+ defer out.Release()
+ v, err := out.(*extensions.VariantArray).Value(0)
+ require.NoError(t, err)
+ assert.Equal(t, "resid", v.Value())
+}
+
+// vgMixedResidual builds a two-row shredded array: row 0 shredded (fill
populates typed_value, top value null),
+// row 1 residual (top typed_value null, top value = resid). Storage comes
from NewShreddedVariantType.
+func vgMixedResidual(t *testing.T, mem memory.Allocator, shredType
arrow.DataType, fill func(b array.Builder), resid variant.Value)
*extensions.VariantArray {
+ t.Helper()
+ vt := extensions.NewShreddedVariantType(shredType)
+ s := vt.StorageType().(*arrow.StructType)
+ mIdx, _ := s.FieldIdx("metadata")
+ vIdx, _ := s.FieldIdx("value")
+ tIdx, _ := s.FieldIdx("typed_value")
+
+ b := array.NewStructBuilder(mem, s)
+ defer b.Release()
+ mb := b.FieldBuilder(mIdx).(*array.BinaryBuilder)
+ vb := b.FieldBuilder(vIdx).(*array.BinaryBuilder)
+
+ b.Append(true)
+ mb.Append(variant.EmptyMetadataBytes[:])
+ vb.AppendNull()
+ fill(b.FieldBuilder(tIdx))
+
+ b.Append(true)
+ mb.Append(resid.Metadata().Bytes())
+ vb.Append(resid.Bytes())
+ b.FieldBuilder(tIdx).AppendNull()
+
+ st := b.NewArray()
+ defer st.Release()
+
+ return array.NewExtensionArrayWithStorage(vt,
st).(*extensions.VariantArray)
+}
+
+// TestVariantGetResidualBackedField covers zeroshade's blocking :233 case for
a root
+// field path: row 1's {"a":2} lives in the top residual, so $.a must return 2
not null.
+func TestVariantGetResidualBackedField(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgMixedResidual(t, mem, arrow.StructOf(arrow.Field{Name: "a",
Type: arrow.PrimitiveTypes.Int64}),
+ func(b array.Builder) {
+ tv := b.(*array.StructBuilder)
+ tv.Append(true)
+ a := tv.FieldBuilder(0).(*array.StructBuilder)
+ a.Append(true)
+ a.FieldBuilder(0).(*array.BinaryBuilder).AppendNull()
+ a.FieldBuilder(1).(*array.Int64Builder).Append(1)
+ }, vgVariant(t, map[string]any{"a": int64(2)}))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a"), AsType: arrow.PrimitiveTypes.Int64})
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ require.Equal(t, 2, ints.Len())
+ assert.EqualValues(t, 1, ints.Value(0))
+ assert.EqualValues(t, 2, ints.Value(1), "residual-backed row must be
reassembled, not nulled")
+}
+
+// TestVariantGetResidualBackedNestedField covers the nested-field case: $.a.b
where
+// row 1's whole {"a":{"b":6}} lives in the top residual.
+func TestVariantGetResidualBackedNestedField(t *testing.T) {
+ mem := memory.DefaultAllocator
+ shred := arrow.StructOf(arrow.Field{Name: "a", Type:
arrow.StructOf(arrow.Field{Name: "b", Type: arrow.PrimitiveTypes.Int64})})
+ arr := vgMixedResidual(t, mem, shred,
+ func(b array.Builder) {
+ tv := b.(*array.StructBuilder)
+ tv.Append(true)
+ a := tv.FieldBuilder(0).(*array.StructBuilder)
+ a.Append(true)
+ a.FieldBuilder(0).(*array.BinaryBuilder).AppendNull()
+ aTV := a.FieldBuilder(1).(*array.StructBuilder)
+ aTV.Append(true)
+ bf := aTV.FieldBuilder(0).(*array.StructBuilder)
+ bf.Append(true)
+ bf.FieldBuilder(0).(*array.BinaryBuilder).AppendNull()
+ bf.FieldBuilder(1).(*array.Int64Builder).Append(5)
+ }, vgVariant(t, map[string]any{"a": map[string]any{"b":
int64(6)}}))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Field("a").Field("b"), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ assert.EqualValues(t, 5, ints.Value(0))
+ assert.EqualValues(t, 6, ints.Value(1), "residual-backed row must be
reassembled, not nulled")
+}
+
+// TestVariantGetResidualBackedListIndex covers the list-index case: [0] where
row 1's
+// whole [30,40] lives in the top residual.
+func TestVariantGetResidualBackedListIndex(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgMixedResidual(t, mem, arrow.ListOf(arrow.PrimitiveTypes.Int64),
+ func(b array.Builder) {
+ lb := b.(*array.ListBuilder)
+ lb.Append(true)
+ el := lb.ValueBuilder().(*array.StructBuilder)
+ for _, v := range []int64{10, 20} {
+ el.Append(true)
+
el.FieldBuilder(0).(*array.BinaryBuilder).AppendNull()
+
el.FieldBuilder(1).(*array.Int64Builder).Append(v)
+ }
+ }, vgVariant(t, []any{int64(30), int64(40)}))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(0), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ assert.EqualValues(t, 10, ints.Value(0))
+ assert.EqualValues(t, 30, ints.Value(1), "residual-backed row must be
reassembled, not nulled")
+}
+
+// TestVariantGetMixedWidthIntegers covers zeroshade :411: variant ints encode
at their
+// natural width, so a wider AsType must not drop rows whose leaf shredded
narrower.
+func TestVariantGetMixedWidthIntegers(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem,
+ map[string]any{"a": int64(1)}, // int8
+ map[string]any{"a": int64(1000)}, // int16
+ map[string]any{"a": int64(5_000_000_000)}, // int64
+ map[string]any{"a": int64(9007199254740993)}) // int64 > 2^53,
must stay exact (no float intermediate)
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a"), AsType: arrow.PrimitiveTypes.Int64})
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ require.Equal(t, 4, ints.Len())
+ assert.EqualValues(t, 1, ints.Value(0))
+ assert.EqualValues(t, 1000, ints.Value(1), "narrower-width leaf must
not be dropped")
+ assert.EqualValues(t, 5_000_000_000, ints.Value(2))
+ assert.EqualValues(t, 9007199254740993, ints.Value(3), "value > 2^53
must be exact, not routed through float64")
+}
+
+// TestVariantGetHeterogeneousLeaves (arrow-rs parity): a valid int64 survives
a
+// narrower-typed sibling; only a non-numeric string nulls.
+func TestVariantGetHeterogeneousLeaves(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem,
+ map[string]any{"a": int64(1)}, // int8 encoding
+ map[string]any{"a": int64(5_000_000_000)}, // int64, does not
fit int8
+ map[string]any{"a": "x"}) // non-numeric ->
null
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a"), AsType: arrow.PrimitiveTypes.Int64})
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ assert.EqualValues(t, 1, ints.Value(0))
+ assert.EqualValues(t, 5_000_000_000, ints.Value(1), "valid int64 must
survive a narrower-typed sibling")
+ assert.True(t, ints.IsNull(2), "non-numeric string must be null")
+}
+
+// TestVariantGetEmptyKey covers zeroshade's blocking path.go:42 case: an
empty-string
+// object key is a field step, not array index 0.
+func TestVariantGetEmptyKey(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, map[string]any{"": int64(42)})
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field(""), AsType: arrow.PrimitiveTypes.Int64})
+ require.NoError(t, err)
+ defer out.Release()
+ assert.EqualValues(t, 42, out.(*array.Int64).Value(0))
+}
+
+// TestVariantGetResidualBackedDeepField exercises the residual break after a
successful
+// columnar descent: row 0 is shredded through a.b, row 1's {"b":6} sits in
a's residual.
+func TestVariantGetResidualBackedDeepField(t *testing.T) {
+ mem := memory.DefaultAllocator
+ shred := arrow.StructOf(arrow.Field{Name: "a", Type:
arrow.StructOf(arrow.Field{Name: "b", Type: arrow.PrimitiveTypes.Int64})})
+ vt := extensions.NewShreddedVariantType(shred)
+ s := vt.StorageType().(*arrow.StructType)
+ mIdx, _ := s.FieldIdx("metadata")
+ vIdx, _ := s.FieldIdx("value")
+ tIdx, _ := s.FieldIdx("typed_value")
+
+ b := array.NewStructBuilder(mem, s)
+ defer b.Release()
+ mb := b.FieldBuilder(mIdx).(*array.BinaryBuilder)
+ vb := b.FieldBuilder(vIdx).(*array.BinaryBuilder)
+ tvb := b.FieldBuilder(tIdx).(*array.StructBuilder) // struct{a}
+ aField := tvb.FieldBuilder(0).(*array.StructBuilder)
+ aVal := aField.FieldBuilder(0).(*array.BinaryBuilder)
+ aTyped := aField.FieldBuilder(1).(*array.StructBuilder) // struct{b}
+ bField := aTyped.FieldBuilder(0).(*array.StructBuilder)
+ bVal := bField.FieldBuilder(0).(*array.BinaryBuilder)
+ bTyped := bField.FieldBuilder(1).(*array.Int64Builder)
+
+ // row 0: fully shredded a.b = 5
+ b.Append(true)
+ mb.Append(variant.EmptyMetadataBytes[:])
+ vb.AppendNull()
+ tvb.Append(true)
+ aField.Append(true)
+ aVal.AppendNull()
+ aTyped.Append(true)
+ bField.Append(true)
+ bVal.AppendNull()
+ bTyped.Append(5)
+
+ // row 1: a is residual-backed with {"b":6} (top typed_value present,
a.value set)
+ resid := vgVariant(t, map[string]any{"b": int64(6)})
+ b.Append(true)
+ mb.Append(resid.Metadata().Bytes())
+ vb.AppendNull()
+ tvb.Append(true)
+ aField.Append(true)
+ aVal.Append(resid.Bytes())
+ aTyped.AppendNull() // a.typed_value null -> recurses
bField/bVal/bTyped null
+
+ st := b.NewArray()
+ defer st.Release()
+ arr := array.NewExtensionArrayWithStorage(vt,
st).(*extensions.VariantArray)
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Field("a").Field("b"), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ ints := out.(*array.Int64)
+ require.Equal(t, 2, ints.Len())
+ assert.EqualValues(t, 5, ints.Value(0))
+ assert.EqualValues(t, 6, ints.Value(1), "mid-level residual row must be
reassembled, not nulled")
+}
+
+// TestVariantGetResidualNoLeak guards the residual break path
(buildTargetVariant +
+// per-row reassembly) against leaks, which TestVariantGetNoLeak does not
reach.
+func TestVariantGetResidualNoLeak(t *testing.T) {
+ mem := memory.NewCheckedAllocator(memory.DefaultAllocator)
+ defer mem.AssertSize(t, 0)
+ ctx := exec.WithAllocator(context.Background(), mem)
+
+ arr := vgMixedResidual(t, mem, arrow.ListOf(arrow.PrimitiveTypes.Int64),
+ func(bld array.Builder) {
+ lb := bld.(*array.ListBuilder)
+ lb.Append(true)
+ el := lb.ValueBuilder().(*array.StructBuilder)
+ for _, v := range []int64{10, 20} {
+ el.Append(true)
+
el.FieldBuilder(0).(*array.BinaryBuilder).AppendNull()
+
el.FieldBuilder(1).(*array.Int64Builder).Append(v)
+ }
+ }, vgVariant(t, []any{int64(30), int64(40)}))
+
+ out, err := compute.VariantGet(ctx, arr, compute.VariantGetOptions{
+ Path: variant.VariantPath{}.Index(0), AsType:
arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+ out.Release()
+ arr.Release()
+}
+
+// vgNonShreddedVals builds a non-shredded array from pre-built values, so a
test can
+// control per-value encoding (e.g. timestamp unit) that vgNonShredded cannot.
+func vgNonShreddedVals(t *testing.T, mem memory.Allocator, vals
...variant.Value) *extensions.VariantArray {
+ t.Helper()
+ bldr := extensions.NewVariantBuilder(mem,
extensions.NewDefaultVariantType())
+ defer bldr.Release()
+ for _, v := range vals {
+ bldr.Append(v)
+ }
+
+ return bldr.NewArray().(*extensions.VariantArray)
+}
+
+func vgTimestamp(t *testing.T, ts arrow.Timestamp, nano bool) variant.Value {
+ t.Helper()
+ var b variant.Builder
+ opts := []variant.AppendOpt{variant.OptTimestampUTC}
+ if nano {
+ opts = append(opts, variant.OptTimestampNano)
+ }
+ require.NoError(t, b.Append(ts, opts...))
+ val, err := b.Build()
+ require.NoError(t, err)
+
+ return val
+}
+
+// TestVariantGetMixedFloatWidths (:411, floats): a Float(32) and a Double(64)
leaf
+// both survive a Float64 request, independent of order.
+func TestVariantGetMixedFloatWidths(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, float32(1.5), float64(2.5))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Float64})
+ require.NoError(t, err)
+ defer out.Release()
+ f := out.(*array.Float64)
+ require.Equal(t, 2, f.Len())
+ assert.InDelta(t, 1.5, f.Value(0), 1e-9)
+ assert.InDelta(t, 2.5, f.Value(1), 1e-9, "Double leaf must not be
dropped by a Float first leaf")
+}
+
+// TestVariantGetIntPlusFloat: a mixed int/float column cast to Float64 widens
the int
+// through the cast kernels rather than nulling it.
+func TestVariantGetIntPlusFloat(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, int64(3), float64(2.5))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Float64})
+ require.NoError(t, err)
+ defer out.Release()
+ f := out.(*array.Float64)
+ assert.InDelta(t, 3.0, f.Value(0), 1e-9)
+ assert.InDelta(t, 2.5, f.Value(1), 1e-9)
+}
+
+// TestVariantGetTypeOrderIndependent (:411): the same two values give the
same result
+// regardless of which row comes first.
+func TestVariantGetTypeOrderIndependent(t *testing.T) {
+ mem := memory.DefaultAllocator
+ forward := vgNonShredded(t, mem, int64(3), float64(2.5))
+ defer forward.Release()
+ reverse := vgNonShredded(t, mem, float64(2.5), int64(3))
+ defer reverse.Release()
+
+ optsF := compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Float64}
+ fwd, err := compute.VariantGet(context.Background(), forward, optsF)
+ require.NoError(t, err)
+ defer fwd.Release()
+ rev, err := compute.VariantGet(context.Background(), reverse, optsF)
+ require.NoError(t, err)
+ defer rev.Release()
+
+ fa, ra := fwd.(*array.Float64), rev.(*array.Float64)
+ assert.InDelta(t, fa.Value(0), ra.Value(1), 1e-9)
+ assert.InDelta(t, fa.Value(1), ra.Value(0), 1e-9)
+ assert.False(t, fa.IsNull(0) || fa.IsNull(1) || ra.IsNull(0) ||
ra.IsNull(1), "no leaf dropped in either order")
+}
+
+// TestVariantGetMixedTimestampUnits: a micros leaf and a nanos leaf of the
same instant
+// both land on it when cast to a nanos target (units are converted, not
reinterpreted).
+func TestVariantGetMixedTimestampUnits(t *testing.T) {
+ mem := memory.DefaultAllocator
+ const micros = arrow.Timestamp(1_600_000_000_000_000)
+ const nanos = arrow.Timestamp(1_600_000_000_000_000_000)
+ arr := vgNonShreddedVals(t, mem, vgTimestamp(t, micros, false),
vgTimestamp(t, nanos, true))
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ AsType: &arrow.TimestampType{Unit: arrow.Nanosecond, TimeZone:
"UTC"},
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ ts := out.(*array.Timestamp)
+ require.Equal(t, 2, ts.Len())
+ assert.EqualValues(t, nanos, ts.Value(0), "micros leaf must be scaled
to nanos, not copied raw")
+ assert.EqualValues(t, nanos, ts.Value(1))
+}
+
+// TestVariantGetMixedDecimalScales: leaves shredded at different scales both
rescale to
+// the requested target scale.
+func TestVariantGetMixedDecimalScales(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShreddedVals(t, mem,
+ vgVariant(t, variant.DecimalValue[decimal.Decimal32]{Scale: 1,
Value: decimal.Decimal32(15)}), // 1.5
+ vgVariant(t, variant.DecimalValue[decimal.Decimal32]{Scale: 2,
Value: decimal.Decimal32(225)})) // 2.25
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ AsType: &arrow.Decimal128Type{Precision: 38, Scale: 2},
+ })
+ require.NoError(t, err)
+ defer out.Release()
+ d := out.(*array.Decimal128)
+ require.Equal(t, 2, d.Len())
+ assert.InDelta(t, 1.5, d.Value(0).ToFloat64(2), 1e-9, "scale-1 leaf
must rescale to scale-2, not drop")
+ assert.InDelta(t, 2.25, d.Value(1).ToFloat64(2), 1e-9)
+}
+
+// TestVariantGetStrictSlowPathErrors (:411/:269): on the reassembly path a
lossy cast
+// errors under Strict rather than nulling.
+func TestVariantGetStrictSlowPathErrors(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, map[string]any{"a": int64(5_000_000_000)})
// overflows int32
+ defer arr.Release()
+
+ _, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: field("a"), AsType: arrow.PrimitiveTypes.Int32, Strict:
true,
+ })
+ require.Error(t, err, "Strict must error on an overflowing cast, not
null it")
+}
+
+// TestVariantGetMixedTypeNoLeak guards the multi-group scatter path (cast +
Concatenate
+// + Take), which the single-type leak tests do not reach.
+// TestVariantGetNestedTypeNotImplemented pins that a nested AsType is
rejected with
+// ErrNotImplemented rather than silently producing an all-null array.
+func TestVariantGetNestedTypeNotImplemented(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, map[string]any{"a": map[string]any{"x":
int64(1)}})
+ defer arr.Release()
+
+ for _, nested := range []arrow.DataType{
+ arrow.StructOf(arrow.Field{Name: "x", Type:
arrow.PrimitiveTypes.Int64}),
+ arrow.ListOf(arrow.PrimitiveTypes.Int64),
+ } {
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a"), AsType: nested})
+ if out != nil {
+ out.Release()
+ }
+ require.ErrorIs(t, err, arrow.ErrNotImplemented, "nested AsType
%s must error, not null", nested)
+ }
+}
+
+func TestVariantGetMixedTypeNoLeak(t *testing.T) {
+ mem := memory.NewCheckedAllocator(memory.DefaultAllocator)
+ defer mem.AssertSize(t, 0)
+ ctx := exec.WithAllocator(context.Background(), mem)
+
+ arr := vgNonShredded(t, mem, int64(3), float64(2.5), nil, "x")
+ out, err := compute.VariantGet(ctx, arr,
compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Float64})
+ require.NoError(t, err)
+ out.Release()
+ arr.Release()
+}
+
+// TestVariantGetInterleavedScatter exercises the multi-group scatter
(Concatenate +
+// TakeArray) with a NON-IDENTITY permutation: two same-typed leaves straddle a
+// differently-typed one, so group order [3,7,2.5] must scatter back to row
order
+// [3,2.5,7]. Every other multi-group test lands in identity order.
+func TestVariantGetInterleavedScatter(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgNonShredded(t, mem, int64(3), float64(2.5), int64(7)) //
Int8{0,2}, Float64{1}
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{AsType: arrow.PrimitiveTypes.Float64})
+ require.NoError(t, err)
+ defer out.Release()
+ f := out.(*array.Float64)
+ require.Equal(t, 3, f.Len())
+ assert.InDelta(t, 3.0, f.Value(0), 1e-9)
+ assert.InDelta(t, 2.5, f.Value(1), 1e-9, "interleaved leaf must scatter
back to its row, not stay in group order")
+ assert.InDelta(t, 7.0, f.Value(2), 1e-9)
+}
+
+// TestVariantGetStrictObjectLeafErrors pins that under Strict an object/array
leaf cast
+// to a primitive errors (impossible cast) rather than silently nulling.
+func TestVariantGetStrictObjectLeafErrors(t *testing.T) {
+ mem := memory.DefaultAllocator
+ for _, v := range []any{
+ map[string]any{"a": map[string]any{"x": int64(1)}}, // object
leaf at $.a
+ map[string]any{"a": []any{int64(1), int64(2)}}, // array
leaf at $.a
+ } {
+ arr := vgNonShredded(t, mem, v)
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: field("a"), AsType: arrow.PrimitiveTypes.Int64,
Strict: true,
+ })
+ if out != nil {
+ out.Release()
+ }
+ arr.Release()
+ require.ErrorIs(t, err, arrow.ErrInvalid, "strict cast of a
non-primitive leaf to Int64 must error")
+ }
+}
+
+// TestVariantGetShreddedFieldOnScalarErrors pins that a field step into a
shredded
+// scalar column errors on the columnar path, matching the per-row GetByPath
path.
+func TestVariantGetShreddedFieldOnScalarErrors(t *testing.T) {
+ mem := memory.DefaultAllocator
+ arr := vgShreddedInt(t, mem, 1, 2, 3) // typed_value is a scalar Int64
column
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{Path: field("a"), AsType: arrow.PrimitiveTypes.Int64})
+ if out != nil {
+ out.Release()
+ }
+ require.ErrorIs(t, err, arrow.ErrInvalid, "field access on a shredded
scalar must error, not return null")
+}
+
+// TestVariantGetUUIDTarget pins that a UUID AsType reaches the UUID cast, not
the nested-type reject.
+func TestVariantGetUUIDTarget(t *testing.T) {
+ mem := memory.DefaultAllocator
+ u := uuid.MustParse("00112233-4455-6677-8899-aabbccddeeff")
+ arr := vgNonShredded(t, mem, map[string]any{"id": u})
+ defer arr.Release()
+
+ out, err := compute.VariantGet(context.Background(), arr,
compute.VariantGetOptions{
+ Path: field("id"), AsType: extensions.NewUUIDType(),
+ })
+ require.NoError(t, err, "UUID target must not be rejected as a nested
type")
+ defer out.Release()
+
+ uarr, ok := out.(*extensions.UUIDArray)
+ require.True(t, ok, "expected *extensions.UUIDArray, got %T", out)
+ require.Equal(t, 1, uarr.Len())
+ require.False(t, uarr.IsNull(0))
+ assert.Equal(t, u, uarr.Value(0))
+}
+
+// TestVariantGetPartialCastFailure pins that non-strict nulls only the
inconvertible row: ["1","bad"]->int64 is [1,null].
+func TestVariantGetPartialCastFailure(t *testing.T) {
+ mem := memory.NewCheckedAllocator(memory.DefaultAllocator)
+ defer mem.AssertSize(t, 0)
+ ctx := exec.WithAllocator(context.Background(), mem)
+ arr := vgNonShredded(t, mem, "1", "bad")
+
+ out, err := compute.VariantGet(ctx, arr, compute.VariantGetOptions{
+ AsType: arrow.PrimitiveTypes.Int64,
+ })
+ require.NoError(t, err)
+
+ ints := out.(*array.Int64)
+ require.Equal(t, 2, ints.Len())
+ assert.False(t, ints.IsNull(0), "valid row must survive a sibling row's
cast failure")
+ assert.EqualValues(t, 1, ints.Value(0))
+ assert.True(t, ints.IsNull(1), "only the inconvertible row is null")
+
+ out.Release()
+ arr.Release()
+}
diff --git a/arrow/extensions/variant.go b/arrow/extensions/variant.go
index fee2e046..a0cc74ed 100644
--- a/arrow/extensions/variant.go
+++ b/arrow/extensions/variant.go
@@ -458,6 +458,11 @@ func (v *VariantArray) IsShredded() bool {
return v.ExtensionType().(*VariantType).typedValueFieldIdx != -1
}
+// VariantType returns the array's extension type without the ExtensionType
cast.
+func (v *VariantArray) VariantType() *VariantType {
+ return v.ExtensionType().(*VariantType)
+}
+
// UnshredVariant returns an equivalent VariantArray in the non-shredded layout
// (a struct of metadata and value), reassembling each row's value from the
// shredded typed_value and value columns. If the array is already non-shredded
@@ -513,6 +518,11 @@ func (v *VariantArray) IsNull(i int) bool {
}
}
+ if vt.valueFieldIdx == -1 {
+ // No residual value column: a null typed_value means the value
is missing.
+ return true
+ }
+
valArr := v.Storage().(*array.Struct).Field(vt.valueFieldIdx)
b := valArr.(arrow.TypedArray[[]byte]).Value(i)
return len(b) == 1 && b[0] == 0 // variant null
diff --git a/parquet/variant/path.go b/parquet/variant/path.go
new file mode 100644
index 00000000..bc46da77
--- /dev/null
+++ b/parquet/variant/path.go
@@ -0,0 +1,109 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package variant
+
+import (
+ "errors"
+ "fmt"
+
+ "github.com/apache/arrow-go/v18/arrow"
+)
+
+// pathElem is one step of a VariantPath: an object field when isField is set,
else an array index.
+type pathElem struct {
+ name string
+ index int
+ isField bool
+}
+
+// VariantPath is an ordered list of steps to navigate into a variant value.
The
+// zero value is the root path; extend it with Field and Index.
+type VariantPath struct {
+ elems []pathElem
+}
+
+// Field returns a copy of the path with an object-field step appended.
+func (p VariantPath) Field(name string) VariantPath {
+ return VariantPath{elems: append(p.grow(), pathElem{name: name,
isField: true})}
+}
+
+// Index returns a copy of the path with an array-index step appended.
+func (p VariantPath) Index(i int) VariantPath {
+ return VariantPath{elems: append(p.grow(), pathElem{index: i})}
+}
+
+// Join returns a copy of the path with other's steps appended.
+func (p VariantPath) Join(other VariantPath) VariantPath {
+ return VariantPath{elems: append(p.grow(), other.elems...)}
+}
+
+func (p VariantPath) grow() []pathElem {
+ return append(make([]pathElem, 0, len(p.elems)+1), p.elems...)
+}
+
+// Len returns the number of steps in the path.
+func (p VariantPath) Len() int { return len(p.elems) }
+
+// StepAt returns the i-th step's name and index, with isField true for an
object-field step.
+func (p VariantPath) StepAt(i int) (name string, index int, isField bool) {
+ e := p.elems[i]
+
+ return e.name, e.index, e.isField
+}
+
+// GetByPath navigates path into v and returns the leaf value. found is false
when
+// the path is cleanly absent (a missing object field, or an out-of-range or
+// non-array index). It returns an error for a type error (a field step into a
+// non-object) or corrupt data (a field id not present in the metadata).
+func (v Value) GetByPath(path VariantPath) (leaf Value, found bool, err error)
{
+ cur := v
+ for _, e := range path.elems {
+ if e.isField {
+ obj, ok := cur.Value().(ObjectValue)
+ if !ok {
+ return Value{}, false, fmt.Errorf("%w: variant
path field %q applied to non-object", arrow.ErrInvalid, e.name)
+ }
+ field, ferr := obj.ValueByKey(e.name)
+ if ferr != nil {
+ if errors.Is(ferr, arrow.ErrNotFound) {
+ return Value{}, false, nil
+ }
+
+ return Value{}, false, ferr
+ }
+ cur = field.Value
+
+ continue
+ }
+
+ arr, ok := cur.Value().(ArrayValue)
+ if !ok {
+ return Value{}, false, nil
+ }
+ if e.index < 0 || uint64(e.index) >= uint64(arr.Len()) {
+ return Value{}, false, nil
+ }
+ el, aerr := arr.Value(uint32(e.index))
+ if aerr != nil {
+ return Value{}, false, nil
+ }
+ cur = el
+ }
+
+ return cur, true, nil
+}
diff --git a/parquet/variant/path_test.go b/parquet/variant/path_test.go
new file mode 100644
index 00000000..9de8b84a
--- /dev/null
+++ b/parquet/variant/path_test.go
@@ -0,0 +1,116 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package variant_test
+
+import (
+ "testing"
+
+ "github.com/apache/arrow-go/v18/arrow"
+ "github.com/apache/arrow-go/v18/parquet/variant"
+ "github.com/stretchr/testify/assert"
+ "github.com/stretchr/testify/require"
+)
+
+func buildVar(t *testing.T, v any) variant.Value {
+ t.Helper()
+ var b variant.Builder
+ require.NoError(t, b.Append(v))
+ val, err := b.Build()
+ require.NoError(t, err)
+
+ return val
+}
+
+func TestGetByPathFieldAndIndex(t *testing.T) {
+ v := buildVar(t, map[string]any{"a": map[string]any{"b": int64(5)},
"arr": []any{int64(10), int64(20)}})
+
+ leaf, found, err :=
v.GetByPath(variant.VariantPath{}.Field("a").Field("b"))
+ require.NoError(t, err)
+ require.True(t, found)
+ assert.EqualValues(t, 5, leaf.Value())
+
+ leaf, found, err =
v.GetByPath(variant.VariantPath{}.Field("arr").Index(1))
+ require.NoError(t, err)
+ require.True(t, found)
+ assert.EqualValues(t, 20, leaf.Value())
+}
+
+func TestGetByPathAbsent(t *testing.T) {
+ v := buildVar(t, map[string]any{"a": int64(1), "arr": []any{int64(10)}})
+
+ for _, p := range []variant.VariantPath{
+ variant.VariantPath{}.Field("missing"), // absent object
field
+ variant.VariantPath{}.Field("arr").Index(9), // out-of-range
index
+ variant.VariantPath{}.Field("a").Index(0), // index into a
scalar
+ variant.VariantPath{}.Index(0), // index into an
object
+ } {
+ _, found, err := v.GetByPath(p)
+ require.NoError(t, err)
+ assert.False(t, found)
+ }
+}
+
+// TestGetByPathFieldOnScalarErrors: a field step into a non-object is a type
error.
+func TestGetByPathFieldOnScalarErrors(t *testing.T) {
+ v := buildVar(t, int64(1))
+ _, _, err := v.GetByPath(variant.VariantPath{}.Field("a"))
+ require.ErrorIs(t, err, arrow.ErrInvalid)
+}
+
+// TestGetByPathHugeIndex: a huge index must not wrap; it is simply absent.
+func TestGetByPathHugeIndex(t *testing.T) {
+ v := buildVar(t, []any{int64(10), int64(20)})
+ _, found, err := v.GetByPath(variant.VariantPath{}.Index(1 << 40))
+ require.NoError(t, err)
+ assert.False(t, found)
+}
+
+func TestVariantPathJoinAndStepAt(t *testing.T) {
+ p :=
variant.VariantPath{}.Field("a").Join(variant.VariantPath{}.Index(2).Field("b"))
+ require.Equal(t, 3, p.Len())
+
+ name, _, isField := p.StepAt(0)
+ assert.Equal(t, "a", name)
+ assert.True(t, isField)
+ name, idx, isField := p.StepAt(1)
+ assert.Equal(t, "", name)
+ assert.Equal(t, 2, idx)
+ assert.False(t, isField)
+ name, _, isField = p.StepAt(2)
+ assert.Equal(t, "b", name)
+ assert.True(t, isField)
+}
+
+// TestGetByPathEmptyKey covers the empty-string object key: Field("") is a
field
+// step distinct from Index(0), so it must resolve the "" key rather than
index 0.
+func TestGetByPathEmptyKey(t *testing.T) {
+ v := buildVar(t, map[string]any{"": int64(42)})
+
+ _, _, isField := variant.VariantPath{}.Field("").StepAt(0)
+ assert.True(t, isField, `Field("") must be a field step, not an index
step`)
+
+ leaf, found, err := v.GetByPath(variant.VariantPath{}.Field(""))
+ require.NoError(t, err)
+ require.True(t, found)
+ assert.EqualValues(t, 42, leaf.Value())
+
+ // Index(0) on the object must not match the "" key.
+ _, found, err = v.GetByPath(variant.VariantPath{}.Index(0))
+ require.NoError(t, err)
+ assert.False(t, found)
+}
