Add table metadata changes for statistics information in table metadata

api/src/main/java/org/apache/iceberg/BlobMetadata.java

@@ -0,0 +1,40 @@
+/*
+ * 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 java.util.List;
+import java.util.Map;
+
+/** A metadata about a statistics or indices blob. */
+public interface BlobMetadata {
+  /** Type of the blob. Never null */
+  String type();
+
+  /** ID of the Iceberg table's snapshot the blob was computed from */
+  long sourceSnapshotId();
+
+  /** Sequence number of the Iceberg table's snapshot the blob was computed from */
+  long sourceSnapshotSequenceNumber();
+
+  /** Ordered list of fields the blob was calculated from. Never null */
+  List<Integer> fields();
+
+  /** Additional properties of the blob, specific to the blob type. Never null */
+  Map<String, String> properties();
+}

api/src/main/java/org/apache/iceberg/StatisticsFile.java

@@ -0,0 +1,47 @@
+/*
+ * 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 java.util.List;
+
+/**
+ * Represents a statistics file in the Puffin format, that can be used to read table data more
+ * efficiently.
+ *
+ * <p>Statistics are informational. A reader can choose to ignore statistics information. Statistics
+ * support is not required to read the table correctly.
+ */
+public interface StatisticsFile {
+  /** ID of the Iceberg table's snapshot the statistics were computed from. */
+  long snapshotId();
+
+  /**
+   * Returns fully qualified path to the file, suitable for constructing a Hadoop Path. Never null.
+   */
+  String path();
+
+  /** Size of the file */
+  long fileSizeInBytes();
+
+  /** Size of the Puffin footer. */
+  long fileFooterSizeInBytes();
+
+  /** List of statistics contained in the file. Never null. */
+  List<BlobMetadata> blobMetadata();
+}

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

@@ -0,0 +1,108 @@
+/*
+ * 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 java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.StringJoiner;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableMap;
+
+public class GenericBlobMetadata implements BlobMetadata {
+  private final String type;
+  private final long sourceSnapshotId;
+  private final long sourceSnapshotSequenceNumber;
+  private final List<Integer> fields;
+  private final Map<String, String> properties;
+
+  public GenericBlobMetadata(
+      String type,
+      long sourceSnapshotId,
+      long sourceSnapshotSequenceNumber,
+      List<Integer> fields,
+      Map<String, String> properties) {
+    Preconditions.checkNotNull(type, "type is null");
+    Preconditions.checkNotNull(fields, "fields is null");
+    Preconditions.checkNotNull(properties, "properties is null");
+    this.type = type;
+    this.sourceSnapshotId = sourceSnapshotId;
+    this.sourceSnapshotSequenceNumber = sourceSnapshotSequenceNumber;
+    this.fields = ImmutableList.copyOf(fields);
+    this.properties = ImmutableMap.copyOf(properties);
+  }
+
+  @Override
+  public String type() {
+    return type;
+  }
+
+  @Override
+  public long sourceSnapshotId() {
+    return sourceSnapshotId;
+  }
+
+  @Override
+  public long sourceSnapshotSequenceNumber() {
+    return sourceSnapshotSequenceNumber;
+  }
+
+  @Override
+  public List<Integer> fields() {
+    return fields;
+  }
+
+  @Override
+  public Map<String, String> properties() {
+    return properties;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    GenericBlobMetadata that = (GenericBlobMetadata) o;
+    return sourceSnapshotId == that.sourceSnapshotId
+        && sourceSnapshotSequenceNumber == that.sourceSnapshotSequenceNumber
+        && Objects.equals(type, that.type)
+        && Objects.equals(fields, that.fields)
+        && Objects.equals(properties, that.properties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(type, sourceSnapshotId, sourceSnapshotSequenceNumber, fields, properties);
+  }
+
+  @Override
+  public String toString() {
+    return new StringJoiner(", ", GenericBlobMetadata.class.getSimpleName() + "[", "]")
+        .add("type='" + type + "'")
+        .add("sourceSnapshotId=" + sourceSnapshotId)
+        .add("sourceSnapshotSequenceNumber=" + sourceSnapshotSequenceNumber)
+        .add("fields=" + fields)
+        .add("properties=" + properties)
+        .toString();
+  }
+}

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

@@ -0,0 +1,105 @@
+/*
+ * 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 java.util.List;
+import java.util.Objects;
+import java.util.StringJoiner;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+
+public class GenericStatisticsFile implements StatisticsFile {
+  private final long snapshotId;
+  private final String path;
+  private final long fileSizeInBytes;
+  private final long fileFooterSizeInBytes;
+  private final List<BlobMetadata> blobMetadata;
+
+  public GenericStatisticsFile(
+      long snapshotId,
+      String path,
+      long fileSizeInBytes,
+      long fileFooterSizeInBytes,
+      List<BlobMetadata> blobMetadata) {
+    Preconditions.checkNotNull(path, "path is null");
+    Preconditions.checkNotNull(blobMetadata, "blobMetadata is null");
+    this.snapshotId = snapshotId;
+    this.path = path;
+    this.fileSizeInBytes = fileSizeInBytes;
+    this.fileFooterSizeInBytes = fileFooterSizeInBytes;
+    this.blobMetadata = ImmutableList.copyOf(blobMetadata);
+  }
+
+  @Override
+  public long snapshotId() {
+    return snapshotId;
+  }
+
+  @Override
+  public String path() {
+    return path;
+  }
+
+  @Override
+  public long fileSizeInBytes() {
+    return fileSizeInBytes;
+  }
+
+  @Override
+  public long fileFooterSizeInBytes() {
+    return fileFooterSizeInBytes;
+  }
+
+  @Override
+  public List<BlobMetadata> blobMetadata() {
+    return blobMetadata;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    GenericStatisticsFile that = (GenericStatisticsFile) o;
+    return snapshotId == that.snapshotId
+        && fileSizeInBytes == that.fileSizeInBytes
+        && fileFooterSizeInBytes == that.fileFooterSizeInBytes
+        && Objects.equals(path, that.path)
+        && Objects.equals(blobMetadata, that.blobMetadata);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(snapshotId, path, fileSizeInBytes, fileFooterSizeInBytes, blobMetadata);
+  }
+
+  @Override
+  public String toString() {
+    return new StringJoiner(", ", GenericStatisticsFile.class.getSimpleName() + "[", "]")
+        .add("snapshotId=" + snapshotId)
+        .add("path='" + path + "'")
+        .add("fileSizeInBytes=" + fileSizeInBytes)
+        .add("fileFooterSizeInBytes=" + fileFooterSizeInBytes)
+        .add("blobMetadata=" + blobMetadata)
+        .toString();
+  }
+}

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

@@ -178,6 +178,46 @@ public void applyTo(TableMetadata.Builder metadataBuilder) {
     }
   }
 
+  class SetStatistics implements MetadataUpdate {
+    private final long snapshotId;
+    private final StatisticsFile statisticsFile;
+
+    public SetStatistics(long snapshotId, StatisticsFile statisticsFile) {
+      this.snapshotId = snapshotId;
+      this.statisticsFile = statisticsFile;
+    }
+
+    public long snapshotId() {
+      return snapshotId;
+    }
+
+    public StatisticsFile statisticsFile() {
+      return statisticsFile;
+    }
+
+    @Override
+    public void applyTo(TableMetadata.Builder metadataBuilder) {
+      metadataBuilder.setStatistics(snapshotId, statisticsFile);
+    }
+  }
+
+  class RemoveStatistics implements MetadataUpdate {
+    private final long snapshotId;
+
+    public RemoveStatistics(long snapshotId) {
+      this.snapshotId = snapshotId;
+    }
+
+    public long snapshotId() {
+      return snapshotId;
+    }
+
+    @Override
+    public void applyTo(TableMetadata.Builder metadataBuilder) {
+      metadataBuilder.removeStatistics(snapshotId);
+    }
+  }
+
   class AddSnapshot implements MetadataUpdate {
     private final Snapshot snapshot;