From eddc8a40379d99fe45d62a11d2c000df4df46719 Mon Sep 17 00:00:00 2001
From: Ryan Blue <blue@apache.org>
Date: Fri, 26 Jun 2020 17:23:44 -0700
Subject: [PATCH] Use Java reflection to get ORC date stats.

---
 .../org/apache/iceberg/orc/OrcMetrics.java    | 36 ++++++++++++++-----
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/orc/src/main/java/org/apache/iceberg/orc/OrcMetrics.java b/orc/src/main/java/org/apache/iceberg/orc/OrcMetrics.java
index e1cba36d5737..86b76972a346 100644
--- a/orc/src/main/java/org/apache/iceberg/orc/OrcMetrics.java
+++ b/orc/src/main/java/org/apache/iceberg/orc/OrcMetrics.java
@@ -21,7 +21,6 @@
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
-import java.sql.Date;
 import java.sql.Timestamp;
 import java.util.List;
 import java.util.Map;
@@ -29,9 +28,11 @@
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
+import java.util.stream.Stream;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.iceberg.Metrics;
 import org.apache.iceberg.Schema;
+import org.apache.iceberg.common.DynFields;
 import org.apache.iceberg.exceptions.RuntimeIOException;
 import org.apache.iceberg.hadoop.HadoopInputFile;
 import org.apache.iceberg.io.InputFile;
@@ -43,7 +44,6 @@
 import org.apache.iceberg.types.Conversions;
 import org.apache.iceberg.types.Type;
 import org.apache.iceberg.types.Types;
-import org.apache.iceberg.util.DateTimeUtil;
 import org.apache.orc.BooleanColumnStatistics;
 import org.apache.orc.ColumnStatistics;
 import org.apache.orc.DateColumnStatistics;
@@ -55,6 +55,7 @@
 import org.apache.orc.TimestampColumnStatistics;
 import org.apache.orc.TypeDescription;
 import org.apache.orc.Writer;
+import org.apache.orc.impl.ColumnStatisticsImpl;
 
 public class OrcMetrics {
 
@@ -157,9 +158,7 @@ private static Optional<ByteBuffer> fromOrcMin(Types.NestedField column,
               .setScale(((Types.DecimalType) column.type()).scale()))
           .orElse(null);
     } else if (columnStats instanceof DateColumnStatistics) {
-      min = Optional.ofNullable(((DateColumnStatistics) columnStats).getMinimum())
-          .map(minStats -> DateTimeUtil.daysFromDate(((Date) minStats).toLocalDate()))
-          .orElse(null);
+      min = Optional.ofNullable(minDayFromEpoch((DateColumnStatistics) columnStats)).orElse(null);
     } else if (columnStats instanceof TimestampColumnStatistics) {
       TimestampColumnStatistics tColStats = (TimestampColumnStatistics) columnStats;
       Timestamp minValue = tColStats.getMinimumUTC();
@@ -195,9 +194,7 @@ private static Optional<ByteBuffer> fromOrcMax(Types.NestedField column,
               .setScale(((Types.DecimalType) column.type()).scale()))
           .orElse(null);
     } else if (columnStats instanceof DateColumnStatistics) {
-      max = Optional.ofNullable(((DateColumnStatistics) columnStats).getMaximum())
-          .map(maxStats -> DateTimeUtil.daysFromDate(((Date) maxStats).toLocalDate()))
-          .orElse(null);
+      max = Optional.ofNullable(maxDayFromEpoch((DateColumnStatistics) columnStats)).orElse(null);
     } else if (columnStats instanceof TimestampColumnStatistics) {
       TimestampColumnStatistics tColStats = (TimestampColumnStatistics) columnStats;
       Timestamp maxValue = tColStats.getMaximumUTC();
@@ -272,4 +269,27 @@ public TypeDescription primitive(Type.PrimitiveType iPrimitive, TypeDescription
       return primitive;
     }
   }
+
+  private static final Class<?> DATE_STATS_IMPL = Stream.of(ColumnStatisticsImpl.class.getDeclaredClasses())
+      .filter(statsClass -> "DateStatisticsImpl".equals(statsClass.getSimpleName()))
+      .findFirst()
+      .orElse(null);
+
+  private static final DynFields.UnboundField<Integer> DATE_MINIMUM = DynFields.builder()
+      .hiddenImpl(DATE_STATS_IMPL, "minimum")
+      .defaultAlwaysNull() // if the minimum field isn't found, don't add a value
+      .build();
+
+  private static final DynFields.UnboundField<Integer> DATE_MAXIMUM = DynFields.builder()
+      .hiddenImpl(DATE_STATS_IMPL, "maximum")
+      .defaultAlwaysNull() // if the minimum field isn't found, don't add a value
+      .build();
+
+  private static Integer minDayFromEpoch(DateColumnStatistics stats) {
+    return DATE_MINIMUM.get(stats);
+  }
+
+  private static Integer maxDayFromEpoch(DateColumnStatistics stats) {
+    return DATE_MAXIMUM.get(stats);
+  }
 }