Core: Make totalRecordCount optional in PartitionStats

core/src/main/java/org/apache/iceberg/PartitionStats.java

@@ -33,7 +33,7 @@ public class PartitionStats implements StructLike {
   private int positionDeleteFileCount;
   private long equalityDeleteRecordCount;
   private int equalityDeleteFileCount;
-  private long totalRecordCount;
+  private Long totalRecordCount; // null by default
   private Long lastUpdatedAt; // null by default
   private Long lastUpdatedSnapshotId; // null by default
 
@@ -78,7 +78,15 @@ public int equalityDeleteFileCount() {
     return equalityDeleteFileCount;
   }
 
+  /**
+   * @deprecated since 1.9.0, will be removed in 1.10.0, use {@link #totalRecords()} instead.
+   */
+  @Deprecated
   public long totalRecordCount() {
+    return totalRecordCount == null ? 0 : totalRecordCount;
+  }
+
+  public Long totalRecords() {
     return totalRecordCount;
   }
 
@@ -150,7 +158,14 @@ public void appendStats(PartitionStats entry) {
     this.positionDeleteFileCount += entry.positionDeleteFileCount;
     this.equalityDeleteRecordCount += entry.equalityDeleteRecordCount;
     this.equalityDeleteFileCount += entry.equalityDeleteFileCount;
-    this.totalRecordCount += entry.totalRecordCount;
+
+    if (entry.totalRecordCount != null) {
+      if (totalRecordCount == null) {
+        this.totalRecordCount = entry.totalRecordCount;
+      } else {
+        this.totalRecordCount += entry.totalRecordCount;
+      }
+    }
 
     if (entry.lastUpdatedAt != null) {
       updateSnapshotInfo(entry.lastUpdatedSnapshotId, entry.lastUpdatedAt);
@@ -236,8 +251,7 @@ public <T> void set(int pos, T value) {
         this.equalityDeleteFileCount = value == null ? 0 : (int) value;
         break;
       case 9:
-        // optional field as per spec, implementation initialize to 0 for counters
-        this.totalRecordCount = value == null ? 0L : (long) value;
+        this.totalRecordCount = (Long) value;
         break;
       case 10:
         this.lastUpdatedAt = (Long) value;

core/src/test/java/org/apache/iceberg/TestPartitionStats.java

@@ -0,0 +1,135 @@
+/*
+ * 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;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import org.apache.iceberg.types.Types;
+import org.junit.jupiter.api.Test;
+
+public class TestPartitionStats {
+
+  private static final PartitionData PARTITION =
+      new PartitionData(
+          Types.StructType.of(Types.NestedField.required(1, "foo", Types.IntegerType.get())));
+
+  @Test
+  public void testAppendWithAllValues() {
+    PartitionStats stats1 =
+        createStats(100L, 15, 1000L, 2L, 500, 1L, 200, 15L, 1625077800000L, 12345L);
+    PartitionStats stats2 = createStats(200L, 7, 500L, 1L, 100, 0L, 50, 7L, 1625077900000L, 12346L);
+
+    stats1.appendStats(stats2);
+
+    validateStats(stats1, 300L, 22, 1500L, 3L, 600, 1L, 250, 22L, 1625077900000L, 12346L);
+  }
+
+  @Test
+  public void testAppendWithThisNullOptionalField() {
+    PartitionStats stats1 = createStats(100L, 15, 1000L, 2L, 500, 1L, 200, null, null, null);
+    PartitionStats stats2 = createStats(100L, 7, 500L, 1L, 100, 0L, 50, 7L, 1625077900000L, 12346L);
+
+    stats1.appendStats(stats2);
+
+    validateStats(stats1, 200L, 22, 1500L, 3L, 600, 1L, 250, 7L, 1625077900000L, 12346L);
+  }
+
+  @Test
+  public void testAppendWithBothNullOptionalFields() {
+    PartitionStats stats1 = createStats(100L, 15, 1000L, 2L, 500, 1L, 200, null, null, null);
+    PartitionStats stats2 = createStats(100L, 7, 500L, 1L, 100, 0L, 50, null, null, null);
+
+    stats1.appendStats(stats2);
+
+    validateStats(stats1, 200L, 22, 1500L, 3L, 600, 1L, 250, null, null, null);
+  }
+
+  @Test
+  public void testAppendWithOtherNullOptionalFields() {
+    PartitionStats stats1 =
+        createStats(100L, 15, 1000L, 2L, 500, 1L, 200, 15L, 1625077900000L, 12346L);
+    PartitionStats stats2 = createStats(100L, 7, 500L, 1L, 100, 0L, 50, null, null, null);
+
+    stats1.appendStats(stats2);
+
+    validateStats(stats1, 200L, 22, 1500L, 3L, 600, 1L, 250, 15L, 1625077900000L, 12346L);
+  }
+
+  @Test
+  public void testAppendEmptyStats() {
+    PartitionStats stats1 = new PartitionStats(PARTITION, 1);
+    PartitionStats stats2 = new PartitionStats(PARTITION, 1);
+
+    stats1.appendStats(stats2);
+
+    validateStats(stats1, 0L, 0, 0L, 0L, 0, 0L, 0, null, null, null);
+  }
+
+  @Test
+  public void testAppendWithDifferentSpec() {
+    PartitionStats stats1 = new PartitionStats(PARTITION, 1);
+    PartitionStats stats2 = new PartitionStats(PARTITION, 2);
+
+    assertThatThrownBy(() -> stats1.appendStats(stats2))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("Spec IDs must match");
+  }
+
+  private PartitionStats createStats(
+      long dataRecordCount,
+      int dataFileCount,
+      long totalDataFileSizeInBytes,
+      long positionDeleteRecordCount,
+      int positionDeleteFileCount,
+      long equalityDeleteRecordCount,
+      int equalityDeleteFileCount,
+      Long totalRecordCount,
+      Long lastUpdatedAt,
+      Long lastUpdatedSnapshotId) {
+
+    PartitionStats stats = new PartitionStats(PARTITION, 1);
+    stats.set(2, dataRecordCount);
+    stats.set(3, dataFileCount);
+    stats.set(4, totalDataFileSizeInBytes);
+    stats.set(5, positionDeleteRecordCount);
+    stats.set(6, positionDeleteFileCount);
+    stats.set(7, equalityDeleteRecordCount);
+    stats.set(8, equalityDeleteFileCount);
+    stats.set(9, totalRecordCount);
+    stats.set(10, lastUpdatedAt);
+    stats.set(11, lastUpdatedSnapshotId);
+
+    return stats;
+  }
+
+  private void validateStats(PartitionStats stats, Object... expectedValues) {
+    // Spec id and partition data should be unchanged
+    assertThat(stats.get(0, PartitionData.class)).isEqualTo(PARTITION);
+    assertThat(stats.get(1, Integer.class)).isEqualTo(1);
+
+    for (int i = 0; i < expectedValues.length; i++) {
+      if (expectedValues[i] == null) {
+        assertThat(stats.get(i + 2, Object.class)).isNull();
+      } else {
+        assertThat(stats.get(i + 2, Object.class)).isEqualTo(expectedValues[i]);
+      }
+    }
+  }
+}