[GitHub] [iceberg] marun224 commented on a diff in pull request #3024: Arrow: Convert dict encoded vectors to their expected Arrow vector types

[GitBox <gi...@apache.org>]

marun224 commented on code in PR #3024:
URL: https://github.com/apache/iceberg/pull/3024#discussion_r1064350851


##########
arrow/src/main/java/org/apache/iceberg/arrow/DictEncodedArrowConverter.java:
##########
@@ -0,0 +1,225 @@
+/*
+ * 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.iceberg.arrow;
+
+import java.math.BigDecimal;
+import java.nio.charset.StandardCharsets;
+import java.util.function.IntConsumer;
+import org.apache.arrow.vector.BaseFixedWidthVector;
+import org.apache.arrow.vector.BaseVariableWidthVector;
+import org.apache.arrow.vector.BigIntVector;
+import org.apache.arrow.vector.DecimalVector;
+import org.apache.arrow.vector.FieldVector;
+import org.apache.arrow.vector.Float4Vector;
+import org.apache.arrow.vector.Float8Vector;
+import org.apache.arrow.vector.TimeMicroVector;
+import org.apache.arrow.vector.TimeStampMicroTZVector;
+import org.apache.arrow.vector.TimeStampMicroVector;
+import org.apache.arrow.vector.TimeStampVector;
+import org.apache.arrow.vector.VarBinaryVector;
+import org.apache.arrow.vector.VarCharVector;
+import org.apache.iceberg.arrow.vectorized.ArrowVectorAccessor;
+import org.apache.iceberg.arrow.vectorized.VectorHolder;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.types.Type;
+import org.apache.iceberg.types.Types;
+
+/** This converts dictionary encoded arrow vectors to a correctly typed arrow vector. */
+public class DictEncodedArrowConverter {
+
+  private DictEncodedArrowConverter() {}
+
+  @SuppressWarnings("checkstyle:CyclomaticComplexity")
+  public static FieldVector toArrowVector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    Preconditions.checkArgument(null != vectorHolder, "VectorHolder cannot be null");
+    Preconditions.checkArgument(null != accessor, "ArrowVectorAccessor cannot be null");
+
+    if (vectorHolder.isDictionaryEncoded()) {
+      if (Type.TypeID.DECIMAL.equals(vectorHolder.icebergType().typeId())) {
+        return toDecimalVector(vectorHolder, accessor);
+      } else if (Type.TypeID.TIMESTAMP.equals(vectorHolder.icebergType().typeId())) {
+        return toTimestampVector(vectorHolder, accessor);
+      } else if (Type.TypeID.LONG.equals(vectorHolder.icebergType().typeId())) {
+        return toBigIntVector(vectorHolder, accessor);
+      } else if (Type.TypeID.FLOAT.equals(vectorHolder.icebergType().typeId())) {
+        return toFloat4Vector(vectorHolder, accessor);
+      } else if (Type.TypeID.DOUBLE.equals(vectorHolder.icebergType().typeId())) {
+        return toFloat8Vector(vectorHolder, accessor);
+      } else if (Type.TypeID.STRING.equals(vectorHolder.icebergType().typeId())) {
+        return toVarCharVector(vectorHolder, accessor);
+      } else if (Type.TypeID.BINARY.equals(vectorHolder.icebergType().typeId())) {
+        return toVarBinaryVector(vectorHolder, accessor);
+      } else if (Type.TypeID.TIME.equals(vectorHolder.icebergType().typeId())) {
+        return toTimeMicroVector(vectorHolder, accessor);
+      }
+
+      throw new IllegalArgumentException(
+          String.format(
+              "Cannot convert dict encoded field '%s' of type '%s' to Arrow "
+                  + "vector as it is currently not supported",
+              vectorHolder.icebergField().name(), vectorHolder.icebergType().typeId()));
+    }
+
+    return vectorHolder.vector();
+  }
+
+  private static boolean isNullAt(VectorHolder vectorHolder, int idx) {
+    return vectorHolder.nullabilityHolder().isNullAt(idx) == 1;
+  }
+
+  private static DecimalVector toDecimalVector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    int precision = ((Types.DecimalType) vectorHolder.icebergType()).precision();
+    int scale = ((Types.DecimalType) vectorHolder.icebergType()).scale();
+
+    DecimalVector vector =
+        new DecimalVector(
+            vectorHolder.vector().getName(),
+            ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+            vectorHolder.vector().getAllocator());
+
+    initVector(
+        vector,
+        vectorHolder,
+        idx -> vector.set(idx, (BigDecimal) accessor.getDecimal(idx, precision, scale)));
+    return vector;
+  }
+
+  private static TimeStampVector toTimestampVector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    TimeStampVector vector;
+    if (((Types.TimestampType) vectorHolder.icebergType()).shouldAdjustToUTC()) {
+      vector =
+          new TimeStampMicroTZVector(
+              vectorHolder.vector().getName(),
+              ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+              vectorHolder.vector().getAllocator());
+    } else {
+      vector =
+          new TimeStampMicroVector(
+              vectorHolder.vector().getName(),
+              ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+              vectorHolder.vector().getAllocator());
+    }
+
+    initVector(vector, vectorHolder, idx -> vector.set(idx, accessor.getLong(idx)));
+    return vector;
+  }
+
+  private static BigIntVector toBigIntVector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    BigIntVector vector =
+        new BigIntVector(
+            vectorHolder.vector().getName(),
+            ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+            vectorHolder.vector().getAllocator());
+
+    initVector(vector, vectorHolder, idx -> vector.set(idx, accessor.getLong(idx)));
+    return vector;
+  }
+
+  private static Float4Vector toFloat4Vector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    Float4Vector vector =
+        new Float4Vector(
+            vectorHolder.vector().getName(),
+            ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+            vectorHolder.vector().getAllocator());
+
+    initVector(vector, vectorHolder, idx -> vector.set(idx, accessor.getFloat(idx)));
+    return vector;
+  }
+
+  private static Float8Vector toFloat8Vector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    Float8Vector vector =
+        new Float8Vector(
+            vectorHolder.vector().getName(),
+            ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+            vectorHolder.vector().getAllocator());
+
+    initVector(vector, vectorHolder, idx -> vector.set(idx, accessor.getDouble(idx)));
+    return vector;
+  }
+
+  private static VarCharVector toVarCharVector(
+      VectorHolder vectorHolder, ArrowVectorAccessor<?, String, ?, ?> accessor) {
+    VarCharVector vector =
+        new VarCharVector(
+            vectorHolder.vector().getName(),
+            ArrowSchemaUtil.convert(vectorHolder.icebergField()).getFieldType(),
+            vectorHolder.vector().getAllocator());
+
+    initVector(
+        vector,
+        vectorHolder,
+        idx -> vector.set(idx, accessor.getUTF8String(idx).getBytes(StandardCharsets.UTF_8)));

Review Comment:
   @nastra,
   
   We need to use setSafe() method instead of set() method. As we are not setting the size initially, there is chance of getting IndexOutOfBoundsException if the varchar column value is lengthy.
   



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