planetlabs · tschaub · Oct 1, 2023 · Oct 1, 2023
diff --git a/cmd/gpq/command/convert.go b/cmd/gpq/command/convert.go
@@ -35,6 +35,7 @@ type ConvertCmd struct {
 	Max                int    `help:"Maximum number of features to consider when building a schema." default:"100"`
 	InputPrimaryColumn string `help:"Primary geometry column name when reading Parquet withtout metadata." default:"geometry"`
 	Compression        string `help:"Parquet compression to use.  Possible values: ${enum}." enum:"uncompressed, snappy, gzip, brotli, zstd" default:"zstd"`
+	RowGroupLength     int    `help:"Maximum number of rows per group when writing Parquet."`
 }
 
 type FormatType string
@@ -149,7 +150,12 @@ func (c *ConvertCmd) Run() error {
 		if outputFormat != ParquetType && outputFormat != GeoParquetType {
 			return errors.New("GeoJSON input can only be converted to GeoParquet")
 		}
-		convertOptions := &geojson.ConvertOptions{MinFeatures: c.Min, MaxFeatures: c.Max, Compression: c.Compression}
+		convertOptions := &geojson.ConvertOptions{
+			MinFeatures:    c.Min,
+			MaxFeatures:    c.Max,
+			Compression:    c.Compression,
+			RowGroupLength: c.RowGroupLength,
+		}
 		return geojson.ToParquet(input, output, convertOptions)
 	}
 
@@ -160,6 +166,7 @@ func (c *ConvertCmd) Run() error {
 	convertOptions := &geoparquet.ConvertOptions{
 		InputPrimaryColumn: c.InputPrimaryColumn,
 		Compression:        c.Compression,
+		RowGroupLength:     c.RowGroupLength,
 	}
 
 	return geoparquet.FromParquet(input, output, convertOptions)

diff --git a/internal/geojson/geojson.go b/internal/geojson/geojson.go
@@ -58,10 +58,11 @@ func FromParquet(reader parquet.ReaderAtSeeker, writer io.Writer) error {
 }
 
 type ConvertOptions struct {
-	MinFeatures int
-	MaxFeatures int
-	Compression string
-	Metadata    string
+	MinFeatures    int
+	MaxFeatures    int
+	Compression    string
+	RowGroupLength int
+	Metadata       string
 }
 
 var defaultOptions = &ConvertOptions{
@@ -80,12 +81,19 @@ func ToParquet(input io.Reader, output io.Writer, convertOptions *ConvertOptions
 	featuresRead := 0
 
 	var pqWriterProps *parquet.WriterProperties
+	var writerOptions []parquet.WriterProperty
 	if convertOptions.Compression != "" {
 		compression, err := pqutil.GetCompression(convertOptions.Compression)
 		if err != nil {
 			return err
 		}
-		pqWriterProps = parquet.NewWriterProperties(parquet.WithCompression(compression))
+		writerOptions = append(writerOptions, parquet.WithCompression(compression))
+	}
+	if convertOptions.RowGroupLength > 0 {
+		writerOptions = append(writerOptions, parquet.WithMaxRowGroupLength(int64(convertOptions.RowGroupLength)))
+	}
+	if len(writerOptions) > 0 {
+		pqWriterProps = parquet.NewWriterProperties(writerOptions...)
 	}
 
 	var featureWriter *geoparquet.FeatureWriter

diff --git a/internal/geojson/geojson_test.go b/internal/geojson/geojson_test.go
@@ -105,6 +105,42 @@ func TestToParquet(t *testing.T) {
 	assert.JSONEq(t, string(expected), geojsonBuffer.String())
 }
 
+func TestToParquetRowGroupLength3(t *testing.T) {
+	geojsonFile, openErr := os.Open("testdata/ten-points.geojson")
+	require.NoError(t, openErr)
+
+	parquetBuffer := &bytes.Buffer{}
+	toParquetErr := geojson.ToParquet(geojsonFile, parquetBuffer, &geojson.ConvertOptions{
+		RowGroupLength: 3,
+	})
+	assert.NoError(t, toParquetErr)
+
+	parquetInput := bytes.NewReader(parquetBuffer.Bytes())
+	fileReader, fileErr := file.NewParquetReader(parquetInput)
+	require.NoError(t, fileErr)
+	defer fileReader.Close()
+
+	assert.Equal(t, 4, fileReader.NumRowGroups())
+}
+
+func TestToParquetRowGroupLength5(t *testing.T) {
+	geojsonFile, openErr := os.Open("testdata/ten-points.geojson")
+	require.NoError(t, openErr)
+
+	parquetBuffer := &bytes.Buffer{}
+	toParquetErr := geojson.ToParquet(geojsonFile, parquetBuffer, &geojson.ConvertOptions{
+		RowGroupLength: 5,
+	})
+	assert.NoError(t, toParquetErr)
+
+	parquetInput := bytes.NewReader(parquetBuffer.Bytes())
+	fileReader, fileErr := file.NewParquetReader(parquetInput)
+	require.NoError(t, fileErr)
+	defer fileReader.Close()
+
+	assert.Equal(t, 2, fileReader.NumRowGroups())
+}
+
 func TestToParquetMismatchedTypes(t *testing.T) {
 	geojsonFile, openErr := os.Open("testdata/mismatched-types.geojson")
 	require.NoError(t, openErr)

diff --git a/internal/geojson/testdata/ten-points.geojson b/internal/geojson/testdata/ten-points.geojson
@@ -0,0 +1,105 @@
+{
+  "type": "FeatureCollection",
+  "features": [
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 0
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [0, 0]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 1
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [1, 1]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 2
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [2, 2]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 3
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [3, 3]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 4
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [4, 4]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 5
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [5, 5]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 6
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [6, 6]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 7
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [7, 7]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 8
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [8, 8]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {
+        "num": 9
+      },
+      "geometry": {
+        "type": "Point",
+        "coordinates": [9, 9]
+      }
+    }
+  ]
+}
diff --git a/internal/geoparquet/geoparquet.go b/internal/geoparquet/geoparquet.go
@@ -21,6 +21,7 @@ import (
 type ConvertOptions struct {
 	InputPrimaryColumn string
 	Compression        string
+	RowGroupLength     int
 }
 
 func getMetadata(fileReader *file.Reader, convertOptions *ConvertOptions) *Metadata {
@@ -171,6 +172,7 @@ func FromParquet(input parquet.ReaderAtSeeker, output io.Writer, convertOptions
 		TransformColumn: transformColumn,
 		BeforeClose:     beforeClose,
 		Compression:     compression,
+		RowGroupLength:  convertOptions.RowGroupLength,
 	}
 
 	return pqutil.TransformByColumn(config)

diff --git a/internal/pqutil/transform.go b/internal/pqutil/transform.go
@@ -23,6 +23,7 @@ type TransformConfig struct {
 	Reader          parquet.ReaderAtSeeker
 	Writer          io.Writer
 	Compression     *compress.Compression
+	RowGroupLength  int
 	TransformSchema SchemaTransformer
 	TransformColumn ColumnTransformer
 	BeforeClose     func(*file.Reader, *file.Writer) error
@@ -50,6 +51,10 @@ func getWriterProperties(config *TransformConfig, fileReader *file.Reader) (*par
 		}
 	}
 
+	if config.RowGroupLength > 0 {
+		writerProperties = append(writerProperties, parquet.WithMaxRowGroupLength(int64(config.RowGroupLength)))
+	}
+
 	return parquet.NewWriterProperties(writerProperties...), nil
 }
 
@@ -104,34 +109,85 @@ func TransformByColumn(config *TransformConfig) error {
 
 	ctx := pqarrow.NewArrowWriteContext(context.Background(), nil)
 
-	numRowGroups := fileReader.NumRowGroups()
-	for rowGroupIndex := 0; rowGroupIndex < numRowGroups; rowGroupIndex += 1 {
-		rowGroupReader := arrowReader.RowGroup(rowGroupIndex)
-		rowGroupWriter := fileWriter.AppendRowGroup()
+	if config.RowGroupLength > 0 {
+		columnReaders := make([]*pqarrow.ColumnReader, numFields)
 		for fieldNum := 0; fieldNum < numFields; fieldNum += 1 {
-			arr, readErr := rowGroupReader.Column(fieldNum).Read(ctx)
-			if readErr != nil {
-				return readErr
+			colReader, err := arrowReader.GetColumn(ctx, fieldNum)
+			if err != nil {
+				return err
 			}
-			if config.TransformColumn != nil {
-				inputField := inputManifest.Fields[fieldNum].Field
-				outputField := outputManifest.Fields[fieldNum].Field
-				transformed, err := config.TransformColumn(inputField, outputField, arr)
-				if err != nil {
-					return err
+			columnReaders[fieldNum] = colReader
+		}
+
+		numRows := fileReader.NumRows()
+		numRowsWritten := int64(0)
+		for {
+			rowGroupWriter := fileWriter.AppendRowGroup()
+			for fieldNum := 0; fieldNum < numFields; fieldNum += 1 {
+				colReader := columnReaders[fieldNum]
+				arr, readErr := colReader.NextBatch(int64(config.RowGroupLength))
+				if readErr != nil {
+					return readErr
 				}
-				if transformed.DataType() != outputField.Type {
-					return fmt.Errorf("transform generated an unexpected type, got %s, expected %s", transformed.DataType().Name(), outputField.Type.Name())
+				if config.TransformColumn != nil {
+					inputField := inputManifest.Fields[fieldNum].Field
+					outputField := outputManifest.Fields[fieldNum].Field
+					transformed, err := config.TransformColumn(inputField, outputField, arr)
+					if err != nil {
+						return err
+					}
+					if transformed.DataType() != outputField.Type {
+						return fmt.Errorf("transform generated an unexpected type, got %s, expected %s", transformed.DataType().Name(), outputField.Type.Name())
+					}
+					arr = transformed
+				}
+				colWriter, colWriterErr := pqarrow.NewArrowColumnWriter(arr, 0, int64(arr.Len()), outputManifest, rowGroupWriter, fieldNum)
+				if colWriterErr != nil {
+					return colWriterErr
+				}
+				if err := colWriter.Write(ctx); err != nil {
+					return err
 				}
-				arr = transformed
-			}
-			colWriter, colWriterErr := pqarrow.NewArrowColumnWriter(arr, 0, int64(arr.Len()), outputManifest, rowGroupWriter, fieldNum)
-			if colWriterErr != nil {
-				return colWriterErr
 			}
-			if err := colWriter.Write(ctx); err != nil {
+			numRowsInGroup, err := rowGroupWriter.NumRows()
+			if err != nil {
 				return err
 			}
+			numRowsWritten += int64(numRowsInGroup)
+			if numRowsWritten >= numRows {
+				break
+			}
+		}
+	} else {
+		numRowGroups := fileReader.NumRowGroups()
+		for rowGroupIndex := 0; rowGroupIndex < numRowGroups; rowGroupIndex += 1 {
+			rowGroupReader := arrowReader.RowGroup(rowGroupIndex)
+			rowGroupWriter := fileWriter.AppendRowGroup()
+			for fieldNum := 0; fieldNum < numFields; fieldNum += 1 {
+				arr, readErr := rowGroupReader.Column(fieldNum).Read(ctx)
+				if readErr != nil {
+					return readErr
+				}
+				if config.TransformColumn != nil {
+					inputField := inputManifest.Fields[fieldNum].Field
+					outputField := outputManifest.Fields[fieldNum].Field
+					transformed, err := config.TransformColumn(inputField, outputField, arr)
+					if err != nil {
+						return err
+					}
+					if transformed.DataType() != outputField.Type {
+						return fmt.Errorf("transform generated an unexpected type, got %s, expected %s", transformed.DataType().Name(), outputField.Type.Name())
+					}
+					arr = transformed
+				}
+				colWriter, colWriterErr := pqarrow.NewArrowColumnWriter(arr, 0, int64(arr.Len()), outputManifest, rowGroupWriter, fieldNum)
+				if colWriterErr != nil {
+					return colWriterErr
+				}
+				if err := colWriter.Write(ctx); err != nil {
+					return err
+				}
+			}
 		}
 	}