(arrow-go) branch main updated: [Go][Parquet] Fix FixedSizeList nullable elements read as NULL (#585)

[zeroshade]

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The following commit(s) were added to refs/heads/main by this push:
     new 5ac5d69e [Go][Parquet] Fix FixedSizeList nullable elements read as 
NULL (#585)
5ac5d69e is described below

commit 5ac5d69e120b4078c54cce1c0e75406bd5727d59
Author: Rick  Morgans <rick.morg...@gmail.com>
AuthorDate: Sun Nov 30 10:38:47 2025 +1030

    [Go][Parquet] Fix FixedSizeList nullable elements read as NULL (#585)
    
    Fixes #584
    
    The `FIXED_SIZE_LIST` case in `pathBuilder.Visit` was missing the
    `nullableInParent` assignment that the `LIST` case has, causing non-null
    values to be read back as NULL.
    
    **Fix:** Add one line to set `nullableInParent` before visiting child
    values.
    
    **Test:** Added `TestFixedSizeListNullableElements` roundtrip test.
---
 parquet/pqarrow/encode_arrow_test.go | 31 +++++++++++++++++++++++++++++++
 parquet/pqarrow/path_builder.go      |  1 +
 2 files changed, 32 insertions(+)

diff --git a/parquet/pqarrow/encode_arrow_test.go 
b/parquet/pqarrow/encode_arrow_test.go
index 3ce4c98e..8b11e75a 100644
--- a/parquet/pqarrow/encode_arrow_test.go
+++ b/parquet/pqarrow/encode_arrow_test.go
@@ -1871,6 +1871,37 @@ func (ps *ParquetIOTestSuite) TestFixedSizeList() {
        ps.roundTripTable(mem, tbl, true)
 }
 
+// TestFixedSizeListNullableElements verifies that FixedSizeList with nullable
+// element type correctly round-trips non-null values through Parquet.
+// This is a regression test for https://github.com/apache/arrow-go/issues/584
+func (ps *ParquetIOTestSuite) TestFixedSizeListNullableElements() {
+       mem := memory.NewCheckedAllocator(memory.DefaultAllocator)
+       defer mem.AssertSize(ps.T(), 0)
+
+       // FixedSizeList<float32>[8] with nullable elements (the default)
+       bldr := array.NewFixedSizeListBuilder(mem, 8, 
arrow.PrimitiveTypes.Float32)
+       defer bldr.Release()
+
+       vb := bldr.ValueBuilder().(*array.Float32Builder)
+
+       // Single row with non-null values [1, 2, 3, 4, 5, 6, 7, 8]
+       bldr.Append(true)
+       vb.AppendValues([]float32{1, 2, 3, 4, 5, 6, 7, 8}, nil)
+
+       data := bldr.NewArray()
+       defer data.Release()
+
+       field := arrow.Field{Name: "embedding", Type: data.DataType(), 
Nullable: true}
+       cnk := arrow.NewChunked(field.Type, []arrow.Array{data})
+       defer data.Release()
+
+       tbl := array.NewTable(arrow.NewSchema([]arrow.Field{field}, nil), 
[]arrow.Column{*arrow.NewColumn(field, cnk)}, -1)
+       defer cnk.Release()
+       defer tbl.Release()
+
+       ps.roundTripTable(mem, tbl, true)
+}
+
 func (ps *ParquetIOTestSuite) TestNull() {
        mem := memory.NewCheckedAllocator(memory.DefaultAllocator)
        defer mem.AssertSize(ps.T(), 0)
diff --git a/parquet/pqarrow/path_builder.go b/parquet/pqarrow/path_builder.go
index 784a2c21..5fd3ffca 100644
--- a/parquet/pqarrow/path_builder.go
+++ b/parquet/pqarrow/path_builder.go
@@ -412,6 +412,7 @@ func (p *pathBuilder) Visit(arr arrow.Array) error {
                        defLevelIfEmpty: p.info.maxDefLevel,
                })
                // if arr.data.offset > 0, slice?
+               p.nullableInParent = 
arr.DataType().(*arrow.FixedSizeListType).ElemField().Nullable
                return p.Visit(larr.ListValues())
        case arrow.DICTIONARY:
                // only currently handle dictionaryarray where the dictionary