feat(java): expose ManifestSummary to java api

java/src/main/java/com/lancedb/lance/ManifestSummary.java

@@ -0,0 +1,115 @@
+/*
+ * Licensed 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 com.lancedb.lance;
+
+import com.google.common.base.MoreObjects;
+
+import java.util.Map;
+
+/** Statistical summary of a dataset manifest for a specific version. */
+public class ManifestSummary {
+  private static final String TOTAL_FRAGMENTS_KEY = "total_fragments";
+  private static final String TOTAL_DATA_FILES_KEY = "total_data_files";
+  private static final String TOTAL_FILES_SIZE_KEY = "total_files_size";
+  private static final String TOTAL_DELETION_FILES_KEY = "total_deletion_files";
+  private static final String TOTAL_DATA_FILE_ROWS_KEY = "total_data_file_rows";
+  private static final String TOTAL_DELETION_FILE_ROWS_KEY = "total_deletion_file_rows";
+  private static final String TOTAL_ROWS_KEY = "total_rows";
+
+  private final long totalFragments;
+  private final long totalDataFiles;
+  private final long totalFilesSize;
+  private final long totalDeletionFiles;
+  private final long totalDataFileRows;
+  private final long totalDeletionFileRows;
+  private final long totalRows;
+
+  public ManifestSummary(
+      long totalFragments,
+      long totalDataFiles,
+      long totalFilesSize,
+      long totalDeletionFiles,
+      long totalDataFileRows,
+      long totalDeletionFileRows,
+      long totalRows) {
+    this.totalFragments = totalFragments;
+    this.totalDataFiles = totalDataFiles;
+    this.totalFilesSize = totalFilesSize;
+    this.totalDeletionFiles = totalDeletionFiles;
+    this.totalDataFileRows = totalDataFileRows;
+    this.totalDeletionFileRows = totalDeletionFileRows;
+    this.totalRows = totalRows;
+  }
+
+  public long getTotalDataFileRows() {
+    return totalDataFileRows;
+  }
+
+  public long getTotalDataFiles() {
+    return totalDataFiles;
+  }
+
+  public long getTotalDeletionFileRows() {
+    return totalDeletionFileRows;
+  }
+
+  public long getTotalDeletionFiles() {
+    return totalDeletionFiles;
+  }
+
+  public long getTotalFilesSize() {
+    return totalFilesSize;
+  }
+
+  public long getTotalFragments() {
+    return totalFragments;
+  }
+
+  public long getTotalRows() {
+    return totalRows;
+  }
+
+  public static ManifestSummary fromMetadata(Map<String, String> map) {
+    long totalFragments = Long.parseLong(map.getOrDefault(TOTAL_FRAGMENTS_KEY, "0"));
+    long totalDataFiles = Long.parseLong(map.getOrDefault(TOTAL_DATA_FILES_KEY, "0"));
+    long totalFilesSize = Long.parseLong(map.getOrDefault(TOTAL_FILES_SIZE_KEY, "0"));
+    long totalDeletionFiles = Long.parseLong(map.getOrDefault(TOTAL_DELETION_FILES_KEY, "0"));
+    long totalDataFileRows = Long.parseLong(map.getOrDefault(TOTAL_DATA_FILE_ROWS_KEY, "0"));
+    long totalDeletionFileRows =
+        Long.parseLong(map.getOrDefault(TOTAL_DELETION_FILE_ROWS_KEY, "0"));
+    long totalRows = Long.parseLong(map.getOrDefault(TOTAL_ROWS_KEY, "0"));
+
+    return new ManifestSummary(
+        totalFragments,
+        totalDataFiles,
+        totalFilesSize,
+        totalDeletionFiles,
+        totalDataFileRows,
+        totalDeletionFileRows,
+        totalRows);
+  }
+
+  @Override
+  public String toString() {
+    return MoreObjects.toStringHelper(this)
+        .add("totalFragments", totalFragments)
+        .add("totalDataFiles", totalDataFiles)
+        .add("totalFilesSize", totalFilesSize)
+        .add("totalDeletionFiles", totalDeletionFiles)
+        .add("totalDataFileRows", totalDataFileRows)
+        .add("totalDeletionFileRows", totalDeletionFileRows)
+        .add("totalRows", totalRows)
+        .toString();
+  }
+}

java/src/main/java/com/lancedb/lance/Version.java

@@ -43,6 +43,10 @@ public long getId() {
     return id;
   }
 
+  public ManifestSummary getManifestSummary() {
+    return ManifestSummary.fromMetadata(metadata);
+  }
+
   @Override
   public String toString() {
     return MoreObjects.toStringHelper(this)

java/src/test/java/com/lancedb/lance/DatasetTest.java

@@ -203,6 +203,21 @@ void testDatasetVersion(@TempDir Path tempDir) {
             assertEquals(3, dataset.version());
             assertTrue(time3.isEqual(dataset.getVersion().getDataTime()));
             assertEquals(3, dataset.latestVersion());
+
+            List<ManifestSummary> summaries =
+                versions.stream().map(Version::getManifestSummary).collect(Collectors.toList());
+            assertEquals(0, summaries.get(0).getTotalFragments());
+            assertEquals(0, summaries.get(0).getTotalDataFiles());
+            assertEquals(0, summaries.get(0).getTotalDataFileRows());
+            assertEquals(0, summaries.get(0).getTotalRows());
+            assertEquals(1, summaries.get(1).getTotalFragments());
+            assertEquals(1, summaries.get(1).getTotalDataFiles());
+            assertEquals(5, summaries.get(1).getTotalDataFileRows());
+            assertEquals(5, summaries.get(1).getTotalRows());
+            assertEquals(2, summaries.get(2).getTotalFragments());
+            assertEquals(2, summaries.get(2).getTotalDataFiles());
+            assertEquals(8, summaries.get(2).getTotalDataFileRows());
+            assertEquals(8, summaries.get(2).getTotalRows());
           }
         }
       }