[GitHub] [arrow] alexandreyc opened a new pull request, #13310: [Go] Fix pqarrow writer for null array

[GitBox]

alexandreyc opened a new pull request, #13310:
URL: https://github.com/apache/arrow/pull/13310

   Hello world,
   
   When converting from Arrow to Parquet it looks like there is a bug with 
arrays of type `arrow.NULL`. Here is a snippet of code to reproduce the bug:
   ```go
   package main
   
   import (
        "fmt"
        "log"
        "os"
   
        "github.com/apache/arrow/go/v9/arrow"
        "github.com/apache/arrow/go/v9/arrow/array"
        "github.com/apache/arrow/go/v9/arrow/memory"
        "github.com/apache/arrow/go/v9/parquet/pqarrow"
   )
   
   const n = 10
   
   func run() error {
        schema := arrow.NewSchema(
                []arrow.Field{
                        {Name: "f1", Type: arrow.Null, Nullable: true},
                },
                nil,
        )
   
        rb := array.NewRecordBuilder(memory.DefaultAllocator, schema)
        defer rb.Release()
   
        for i := 0; i < n; i++ {
                rb.Field(0).(*array.NullBuilder).AppendNull()
        }
   
        rec := rb.NewRecord()
        defer rec.Release()
   
        for i, col := range rec.Columns() {
                fmt.Printf("column[%d] %q: %v\n", i, rec.ColumnName(i), col)
        }
   
        f, err := os.Create("output.parquet")
        if err != nil {
                return err
        }
        defer f.Close()
   
        w, err := pqarrow.NewFileWriter(rec.Schema(), f, nil, 
pqarrow.DefaultWriterProps())
        if err != nil {
                return err
        }
        defer w.Close()
   
        err = w.Write(rec)
        if err != nil {
                return err
        }
   
        return nil
   }
   
   func main() {
        if err := run(); err != nil {
                log.Fatal(err)
        }
   }
   ```
   
   I'm not 100% sure if my fix is the best, so feel free to correct me.
   
   Thanks
   
   A
   


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