[ 
https://issues.apache.org/jira/browse/BEAM-8933?focusedWorklogId=378554&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-378554
 ]

ASF GitHub Bot logged work on BEAM-8933:
----------------------------------------

                Author: ASF GitHub Bot
            Created on: 28/Jan/20 23:05
            Start Date: 28/Jan/20 23:05
    Worklog Time Spent: 10m 
      Work Description: emkornfield commented on pull request #10384: 
[BEAM-8933] Utilities for converting Arrow schemas and reading Arrow batches as 
Rows
URL: https://github.com/apache/beam/pull/10384#discussion_r372108633
 
 

 ##########
 File path: 
sdks/java/extensions/arrow/src/main/java/org/apache/beam/sdk/extensions/arrow/ArrowConversion.java
 ##########
 @@ -0,0 +1,448 @@
+/*
+ * 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 org.apache.beam.sdk.extensions.arrow;
+
+import static 
org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Preconditions.checkArgument;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import javax.annotation.Nullable;
+import org.apache.arrow.vector.FieldVector;
+import org.apache.arrow.vector.VectorSchemaRoot;
+import org.apache.arrow.vector.types.TimeUnit;
+import org.apache.arrow.vector.types.pojo.ArrowType;
+import org.apache.arrow.vector.util.Text;
+import org.apache.beam.sdk.annotations.Experimental;
+import org.apache.beam.sdk.schemas.CachingFactory;
+import org.apache.beam.sdk.schemas.Factory;
+import org.apache.beam.sdk.schemas.FieldValueGetter;
+import org.apache.beam.sdk.schemas.Schema;
+import org.apache.beam.sdk.schemas.Schema.Field;
+import org.apache.beam.sdk.schemas.Schema.FieldType;
+import org.apache.beam.sdk.schemas.logicaltypes.FixedBytes;
+import org.apache.beam.sdk.values.Row;
+import org.joda.time.DateTime;
+import org.joda.time.DateTimeZone;
+
+/**
+ * Utilities to create {@link Iterable}s of Beam {@link Row} instances backed 
by Arrow record
+ * batches.
+ */
+@Experimental(Experimental.Kind.SCHEMAS)
+public class ArrowConversion {
+  /** Converts Arrow schema to Beam row schema. */
+  public static Schema toBeamSchema(org.apache.arrow.vector.types.pojo.Schema 
schema) {
+    return toBeamSchema(schema.getFields());
+  }
+
+  public static Schema 
toBeamSchema(List<org.apache.arrow.vector.types.pojo.Field> fields) {
+    Schema.Builder builder = Schema.builder();
+    for (org.apache.arrow.vector.types.pojo.Field field : fields) {
+      Field beamField = toBeamField(field);
+      builder.addField(beamField);
+    }
+    return builder.build();
+  }
+
+  /** Get Beam Field from Arrow Field. */
+  private static Field toBeamField(org.apache.arrow.vector.types.pojo.Field 
field) {
+    FieldType beamFieldType = toFieldType(field.getFieldType(), 
field.getChildren());
+    return Field.of(field.getName(), beamFieldType);
+  }
+
+  /** Converts Arrow FieldType to Beam FieldType. */
+  private static FieldType toFieldType(
+      org.apache.arrow.vector.types.pojo.FieldType arrowFieldType,
+      List<org.apache.arrow.vector.types.pojo.Field> childrenFields) {
+    FieldType fieldType =
+        arrowFieldType
+            .getType()
+            .accept(
+                new ArrowType.ArrowTypeVisitor<FieldType>() {
+                  @Override
+                  public FieldType visit(ArrowType.Null type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Struct type) {
+                    return FieldType.row(toBeamSchema(childrenFields));
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.List type) {
+                    checkArgument(
+                        childrenFields.size() == 1,
+                        "Encountered "
+                            + childrenFields.size()
+                            + " child fields for list type, expected 1");
+                    return 
FieldType.array(toBeamField(childrenFields.get(0)).getType());
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.FixedSizeList type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Union type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Map type) {
+                    checkArgument(
+                        childrenFields.size() == 2,
+                        "Encountered "
+                            + childrenFields.size()
+                            + " child fields for map type, expected 2");
+                    return FieldType.map(
+                        toBeamField(childrenFields.get(0)).getType(),
+                        toBeamField(childrenFields.get(1)).getType());
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Int type) {
+                    if (!type.getIsSigned()) {
+                      throw new IllegalArgumentException("Unsigned integers 
are not supported.");
+                    }
+                    switch (type.getBitWidth()) {
+                      case 8:
+                        return FieldType.BYTE;
+                      case 16:
+                        return FieldType.INT16;
+                      case 32:
+                        return FieldType.INT32;
+                      case 64:
+                        return FieldType.INT64;
+                      default:
+                        throw new IllegalArgumentException(
+                            "Unsupported integer bit width: " + 
type.getBitWidth());
+                    }
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.FloatingPoint type) {
+                    switch (type.getPrecision()) {
+                      case SINGLE:
+                        return FieldType.FLOAT;
+                      case DOUBLE:
+                        return FieldType.DOUBLE;
+                      default:
+                        throw new IllegalArgumentException(
+                            "Unsupported floating-point precision: " + 
type.getPrecision().name());
+                    }
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Utf8 type) {
+                    return FieldType.STRING;
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Binary type) {
+                    return FieldType.BYTES;
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.FixedSizeBinary type) {
+                    return 
FieldType.logicalType(FixedBytes.of(type.getByteWidth()));
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Bool type) {
+                    return FieldType.BOOLEAN;
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Decimal type) {
+                    // FieldType.DECIMAL isn't perfect here since arrow 
decimal has a
+                    // scale/precision fixed by the schema, but 
FieldType.DECIMAL uses a BigDecimal,
+                    // whose precision/scale can change from row to row.
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Date type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Time type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Timestamp type) {
+                    if (type.getUnit() == TimeUnit.MILLISECOND
+                        || type.getUnit() == TimeUnit.MICROSECOND) {
+                      return FieldType.DATETIME;
+                    } else {
+                      throw new IllegalArgumentException(
+                          "Unsupported timestamp unit: " + 
type.getUnit().name());
+                    }
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Interval type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+
+                  @Override
+                  public FieldType visit(ArrowType.Duration type) {
+                    throw new IllegalArgumentException(
+                        "Type \'" + type.toString() + "\' not supported.");
+                  }
+                });
+    return fieldType.withNullable(arrowFieldType.isNullable());
+  }
+
+  /**
+   * Returns an {@link Iterable<Row>} backed by the Arrow record batch stored 
in {@code
+   * vectorSchemaRoot}.
+   *
+   * <p>Note this is a lazy interface. The data in the underlying Arrow buffer 
is not read until a
+   * field of one of the returned {@link Row}s is accessed.
+   */
+  public static Iterable<Row> rowsFromRecordBatch(
+      Schema schema, VectorSchemaRoot vectorSchemaRoot) {
+    return new RecordBatchIterable(schema, vectorSchemaRoot);
+  }
+
+  public static Iterable<Row> rowsFromRecordBatch(VectorSchemaRoot 
vectorSchemaRoot) {
+    return rowsFromRecordBatch(toBeamSchema(vectorSchemaRoot.getSchema()), 
vectorSchemaRoot);
+  }
+
+  private static class VectorSchemaRootRowIterator implements Iterator<Row> {
+    private static final ArrowValueConverterVisitor valueConverterVisitor =
+        new ArrowValueConverterVisitor();
+    private final Schema schema;
+    private final VectorSchemaRoot vectorSchemaRoot;
+    private final Factory<List<FieldValueGetter>> fieldValueGetters;
+    private Integer currRowIndex;
+
+    private static class FieldVectorListValueGetterFactory
+        implements Factory<List<FieldValueGetter>> {
+      private final List<FieldVector> fieldVectors;
+
+      static FieldVectorListValueGetterFactory of(List<FieldVector> 
fieldVectors) {
+        return new FieldVectorListValueGetterFactory(fieldVectors);
+      }
+
+      private FieldVectorListValueGetterFactory(List<FieldVector> 
fieldVectors) {
+        this.fieldVectors = fieldVectors;
+      }
+
+      @Override
+      public List<FieldValueGetter> create(Class<?> clazz, Schema schema) {
+        return this.fieldVectors.stream()
+            .map(
+                (fieldVector) -> {
+                  Function<Object, Object> conversionFunction =
+                      
fieldVector.getField().getFieldType().getType().accept(valueConverterVisitor);
+                  if (conversionFunction == null) {
+                    return new FieldValueGetter<Integer, Object>() {
+                      @Nullable
+                      @Override
+                      public Object get(Integer rowIndex) {
+                        return fieldVector.getObject(rowIndex);
+                      }
+
+                      @Override
+                      public String name() {
+                        return fieldVector.getField().getName();
+                      }
+                    };
+                  } else {
+                    return new FieldValueGetter<Integer, Object>() {
+                      @Nullable
+                      @Override
+                      public Object get(Integer rowIndex) {
+                        Object value = fieldVector.getObject(rowIndex);
+                        if (value == null) {
+                          return null;
+                        }
+
+                        return conversionFunction.apply(value);
+                      }
+
+                      @Override
+                      public String name() {
+                        return fieldVector.getField().getName();
+                      }
+                    };
+                  }
+                })
+            .collect(Collectors.toList());
+      }
+    }
+
+    // TODO: Consider using ByteBuddyUtils.TypeConversion for this
+    private static class ArrowValueConverterVisitor
+        implements ArrowType.ArrowTypeVisitor<Function<Object, Object>> {
+      @Override
+      public Function<Object, Object> visit(ArrowType.Null type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Struct type) {
+        // TODO: code to create a row.
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.List type) {
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.FixedSizeList type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Union type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Map type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Duration type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Int type) {
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.FloatingPoint type) {
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Utf8 type) {
+        return (Object text) -> ((Text) text).toString();
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Binary type) {
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.FixedSizeBinary type) {
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Bool type) {
+        return null;
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Decimal type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Date type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Time type) {
+        throw new IllegalArgumentException("Type \'" + type.toString() + "\' 
not supported.");
+      }
+
+      @Override
+      public Function<Object, Object> visit(ArrowType.Timestamp type) {
+        DateTimeZone tz = DateTimeZone.forID(type.getTimezone());
 
 Review comment:
   is it ok for tz to be null or empty string here?  I forget the details on 
the java implementation but the Arrow spec differentiates between timestamps 
[with/without 
timezones](https://github.com/apache/arrow/blob/master/format/Schema.fbs#L178)
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 378554)
    Time Spent: 10h 10m  (was: 10h)

> BigQuery IO should support read/write in Arrow format
> -----------------------------------------------------
>
>                 Key: BEAM-8933
>                 URL: https://issues.apache.org/jira/browse/BEAM-8933
>             Project: Beam
>          Issue Type: Improvement
>          Components: io-java-gcp
>            Reporter: Kirill Kozlov
>            Assignee: Kirill Kozlov
>            Priority: Major
>          Time Spent: 10h 10m
>  Remaining Estimate: 0h
>
> As of right now BigQuery uses Avro format for reading and writing.
> We should add a config to BigQueryIO to specify which format to use: Arrow or 
> Avro (with Avro as default).



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