add compact DB mode (--compact-db) to de-duplicate mbtiles output

planetiler-basemap/src/test/java/com/onthegomap/planetiler/basemap/util/VerifyMonacoTest.java

@@ -7,9 +7,11 @@
 import com.onthegomap.planetiler.VectorTile;
 import com.onthegomap.planetiler.geo.TileCoord;
 import com.onthegomap.planetiler.mbtiles.Mbtiles;
+import com.onthegomap.planetiler.mbtiles.TileEncodingResult;
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
+import java.util.OptionalInt;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -51,7 +53,7 @@ void testStilInvalidWithOneTile() throws IOException {
         VectorTile.encodeGeometry(point(0, 0)),
         Map.of()
       )));
-      writer.write(TileCoord.ofXYZ(0, 0, 0), gzip(tile.encode()));
+      writer.write(new TileEncodingResult(TileCoord.ofXYZ(0, 0, 0), gzip(tile.encode()), OptionalInt.empty()));
     }
     assertInvalid(mbtiles);
   }

planetiler-benchmarks/src/main/java/com/onthegomap/planetiler/benchmarks/BenchmarkMbtilesRead.java

@@ -0,0 +1,124 @@
+package com.onthegomap.planetiler.benchmarks;
+
+import com.google.common.base.Stopwatch;
+import com.onthegomap.planetiler.config.Arguments;
+import com.onthegomap.planetiler.geo.TileCoord;
+import com.onthegomap.planetiler.mbtiles.Mbtiles;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.time.Duration;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class BenchmarkMbtilesRead {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(BenchmarkMbtilesRead.class);
+
+  private static final String SELECT_RANDOM_COORDS =
+    "select tile_column, tile_row, zoom_level from tiles order by random() limit ?";
+
+  public static void main(String[] args) throws Exception {
+
+    Arguments arguments = Arguments.fromArgs(args);
+    int repetitions = arguments.getInteger("bench_repetitions", "number of repetitions", 10);
+    int nrTileReads = arguments.getInteger("bench_nr_tile_reads", "number of tiles to read", 500_000);
+    int preWarms = arguments.getInteger("bench_pre_warms", "number of pre warm runs", 3);
+
+    List<Path> mbtilesPaths = arguments.getList("bench_mbtiles", "the mbtiles file to read from", List.of()).stream()
+      .map(Paths::get).toList();
+
+
+    if (mbtilesPaths.isEmpty()) {
+      throw new IllegalArgumentException("pass one or many paths to the same mbtiles file");
+    }
+
+    mbtilesPaths.stream().forEach(p -> {
+      if (!Files.exists(p) || !Files.isRegularFile(p)) {
+        throw new IllegalArgumentException("%s does not exists".formatted(p));
+      }
+    });
+
+    List<TileCoord> randomCoordsToFetchPerRepetition = new LinkedList<>();
+
+    do {
+      try (var db = Mbtiles.newReadOnlyDatabase(mbtilesPaths.get(0))) {
+        try (var statement = db.connection().prepareStatement(SELECT_RANDOM_COORDS)) {
+          statement.setInt(1, nrTileReads - randomCoordsToFetchPerRepetition.size());
+          var rs = statement.executeQuery();
+          while (rs.next()) {
+            int x = rs.getInt("tile_column");
+            int y = rs.getInt("tile_row");
+            int z = rs.getInt("zoom_level");
+            randomCoordsToFetchPerRepetition.add(TileCoord.ofXYZ(x, (1 << z) - 1 - y, z));
+          }
+        }
+      }
+    } while (randomCoordsToFetchPerRepetition.size() < nrTileReads);
+
+    Map<Path, Double> avgReadOperationsPerSecondPerDb = new HashMap<>();
+    for (Path dbPath : mbtilesPaths) {
+      List<ReadResult> results = new LinkedList<>();
+
+      LOGGER.info("working on {}", dbPath);
+
+      for (int preWarm = 0; preWarm < preWarms; preWarm++) {
+        readEachTile(randomCoordsToFetchPerRepetition, dbPath);
+      }
+
+      for (int rep = 0; rep < repetitions; rep++) {
+        results.add(readEachTile(randomCoordsToFetchPerRepetition, dbPath));
+      }
+      var readOperationsPerSecondStats =
+        results.stream().mapToDouble(ReadResult::readOperationsPerSecond).summaryStatistics();
+      LOGGER.info("readOperationsPerSecondStats: {}", readOperationsPerSecondStats);
+
+      avgReadOperationsPerSecondPerDb.put(dbPath, readOperationsPerSecondStats.getAverage());
+    }
+
+    List<Path> keysSorted = avgReadOperationsPerSecondPerDb.entrySet().stream()
+      .sorted((o1, o2) -> o1.getValue().compareTo(o2.getValue()))
+      .map(Map.Entry::getKey)
+      .toList();
+
+    LOGGER.info("diffs");
+    for (int i = 0; i < keysSorted.size() - 1; i++) {
+      for (int j = i + 1; j < keysSorted.size(); j++) {
+        Path db0 = keysSorted.get(i);
+        double avg0 = avgReadOperationsPerSecondPerDb.get(db0);
+        Path db1 = keysSorted.get(j);
+        double avg1 = avgReadOperationsPerSecondPerDb.get(db1);
+
+        double diff = avg1 * 100 / avg0 - 100;
+
+        LOGGER.info("\"{}\" to \"{}\": avg read operations per second improved by {}%", db0, db1, diff);
+      }
+    }
+  }
+
+  private static ReadResult readEachTile(List<TileCoord> coordsToFetch, Path dbPath) throws IOException {
+    try (var db = Mbtiles.newReadOnlyDatabase(dbPath)) {
+      db.getTile(0, 0, 0); // trigger prepared statement creation
+      var totalSw = Stopwatch.createStarted();
+      for (var coordToFetch : coordsToFetch) {
+        if (db.getTile(coordToFetch) == null) {
+          throw new IllegalStateException("%s should exist in %s".formatted(coordToFetch, dbPath));
+        }
+      }
+      totalSw.stop();
+      return new ReadResult(totalSw.elapsed(), coordsToFetch.size());
+    }
+  }
+
+  private record ReadResult(Duration duration, int coordsFetchedCount) {
+    double readOperationsPerSecond() {
+      double secondsFractional = duration.toNanos() / 1E9;
+      return coordsFetchedCount / secondsFractional;
+    }
+  }
+}

planetiler-benchmarks/src/main/java/com/onthegomap/planetiler/benchmarks/BenchmarkMbtilesWriter.java

@@ -0,0 +1,142 @@
+package com.onthegomap.planetiler.benchmarks;
+
+import com.google.common.base.Stopwatch;
+import com.onthegomap.planetiler.config.Arguments;
+import com.onthegomap.planetiler.config.PlanetilerConfig;
+import com.onthegomap.planetiler.geo.TileCoord;
+import com.onthegomap.planetiler.mbtiles.Mbtiles;
+import com.onthegomap.planetiler.mbtiles.Mbtiles.BatchedTileWriter;
+import com.onthegomap.planetiler.mbtiles.TileEncodingResult;
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.DoubleSummaryStatistics;
+import java.util.OptionalInt;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class BenchmarkMbtilesWriter {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(BenchmarkMbtilesWriter.class);
+
+  public static void main(String[] args) throws IOException {
+
+    Arguments arguments = Arguments.fromArgs(args);
+
+    int tilesToWrite = arguments.getInteger("bench_tiles_to_write", "number of tiles to write", 1_000_000);
+    int repetitions = arguments.getInteger("bench_repetitions", "number of repetitions", 10);
+    /*
+     * select count(distinct(tile_data_id)) * 100.0 / count(*) from tiles_shallow
+     * => ~8% (Australia)
+     */
+    int distinctTilesInPercent = arguments.getInteger("bench_distinct_tiles", "distinct tiles in percent", 10);
+    /*
+     * select avg(length(tile_data)) 
+     * from (select tile_data_id from tiles_shallow group by tile_data_id having count(*) = 1) as x 
+     * join tiles_data using(tile_data_id)
+     * => ~785 (Australia)
+     */
+    int distinctTileDataSize =
+      arguments.getInteger("bench_distinct_tile_data_size", "distinct tile data size in bytes", 800);
+    /*
+     * select avg(length(tile_data)) 
+     * from (select tile_data_id from tiles_shallow group by tile_data_id having count(*) > 1) as x 
+     * join tiles_shallow using(tile_data_id) 
+     * join tiles_data using(tile_data_id)
+     * => ~93 (Australia)
+     */
+    int dupeTileDataSize = arguments.getInteger("bench_dupe_tile_data_size", "dupe tile data size in bytes", 100);
+    /*
+     * select count(*) * 100.0 / sum(usage_count) 
+     * from (select tile_data_id, count(*) as usage_count from tiles_shallow group by tile_data_id having count(*) > 1)
+     * => ~0.17% (Australia)
+     */
+    int dupeSpreadInPercent = arguments.getInteger("bench_dupe_spread", "dupe spread in percent", 10);
+
+    byte[] distinctTileData = createFilledByteArray(distinctTileDataSize);
+    byte[] dupeTileData = createFilledByteArray(dupeTileDataSize);
+
+    PlanetilerConfig config = PlanetilerConfig.from(arguments);
+
+    DoubleSummaryStatistics tileWritesPerSecondsStats = new DoubleSummaryStatistics();
+
+    for (int repetition = 0; repetition < repetitions; repetition++) {
+
+      Path outputPath = getTempOutputPath();
+      try (var mbtiles = Mbtiles.newWriteToFileDatabase(outputPath, config.compactDb())) {
+
+        mbtiles.createTables();
+        if (!config.deferIndexCreation()) {
+          mbtiles.addTileIndex();
+        }
+
+        try (var writer = mbtiles.newBatchedTileWriter()) {
+          Stopwatch sw = Stopwatch.createStarted();
+          writeTiles(writer, tilesToWrite, distinctTilesInPercent, distinctTileData, dupeTileData, dupeSpreadInPercent);
+          sw.stop();
+          double secondsFractional = sw.elapsed(TimeUnit.NANOSECONDS) / 1E9;
+          double tileWritesPerSecond = tilesToWrite / secondsFractional;
+          tileWritesPerSecondsStats.accept(tileWritesPerSecond);
+        }
+
+      } finally {
+        Files.delete(outputPath);
+      }
+    }
+
+    LOGGER.info("tileWritesPerSecondsStats: {}", tileWritesPerSecondsStats);
+  }
+
+
+  private static void writeTiles(BatchedTileWriter writer, int tilesToWrite, int distinctTilesInPercent,
+    byte[] distinctTileData, byte[] dupeTileData, int dupeSpreadInPercent) {
+
+    int dupesToWrite = (int) Math.round(tilesToWrite * (100 - distinctTilesInPercent) / 100.0);
+    int dupeHashMod = (int) Math.round(dupesToWrite * dupeSpreadInPercent / 100.0);
+    int tilesWritten = 0;
+    int dupeCounter = 0;
+    for (int z = 0; z <= 14; z++) {
+      int maxCoord = 1 << z;
+      for (int x = 0; x < maxCoord; x++) {
+        for (int y = 0; y < maxCoord; y++) {
+
+          TileCoord coord = TileCoord.ofXYZ(x, y, z);
+          TileEncodingResult toWrite;
+          if (tilesWritten % 100 < distinctTilesInPercent) {
+            toWrite = new TileEncodingResult(coord, distinctTileData, OptionalInt.empty());
+          } else {
+            ++dupeCounter;
+            int hash = dupeHashMod == 0 ? 0 : dupeCounter % dupeHashMod;
+            toWrite = new TileEncodingResult(coord, dupeTileData, OptionalInt.of(hash));
+          }
+
+          writer.write(toWrite);
+
+          if (++tilesWritten >= tilesToWrite) {
+            return;
+          }
+        }
+      }
+    }
+  }
+
+  private static Path getTempOutputPath() {
+    File f;
+    try {
+      f = File.createTempFile("planetiler", ".mbtiles");
+    } catch (IOException e) {
+      throw new IllegalStateException(e);
+    }
+    f.deleteOnExit();
+    return f.toPath();
+  }
+
+  private static byte[] createFilledByteArray(int len) {
+    byte[] data = new byte[len];
+    new Random(0).nextBytes(data);
+    return data;
+  }
+}

planetiler-core/src/main/java/com/onthegomap/planetiler/collection/FeatureGroup.java

@@ -12,6 +12,7 @@
 import com.onthegomap.planetiler.util.CloseableConusmer;
 import com.onthegomap.planetiler.util.CommonStringEncoder;
 import com.onthegomap.planetiler.util.DiskBacked;
+import com.onthegomap.planetiler.util.Hashing;
 import com.onthegomap.planetiler.util.LayerStats;
 import java.io.Closeable;
 import java.io.IOException;
@@ -341,6 +342,22 @@ public TileCoord tileCoord() {
       return tileCoord;
     }
 
+    /**
+     * Generates a hash over the feature's relevant data: layer, geometry, and attributes. The coordinates are
+     * <b>not</b> part of the hash.
+     * <p>
+     * Used as an optimization to avoid writing the same (ocean) tiles over and over again.
+     */
+    public int generateContentHash() {
+      int hash = Hashing.FNV1_32_INIT;
+      for (var feature : entries) {
+        byte layerId = extractLayerIdFromKey(feature.key());
+        hash = Hashing.fnv1a32(hash, layerId);
+        hash = Hashing.fnv1a32(hash, feature.value());
+      }
+      return hash;
+    }
+
     /**
      * Returns true if {@code other} contains features with identical layer, geometry, and attributes, as this tile -
      * even if the tiles have separate coordinates.
@@ -363,6 +380,7 @@ public boolean hasSameContents(TileFeatures other) {
       return true;
     }
 
+
     private VectorTile.Feature decodeVectorTileFeature(SortableFeature entry) {
       try (MessageUnpacker unpacker = MessagePack.newDefaultUnpacker(entry.value())) {
         long group;

planetiler-core/src/main/java/com/onthegomap/planetiler/config/PlanetilerConfig.java

@@ -39,7 +39,8 @@ public record PlanetilerConfig(
   double minFeatureSizeBelowMaxZoom,
   double simplifyToleranceAtMaxZoom,
   double simplifyToleranceBelowMaxZoom,
-  boolean osmLazyReads
+  boolean osmLazyReads,
+  boolean compactDb
 ) {
 
   public static final int MIN_MINZOOM = 0;
@@ -135,6 +136,9 @@ public static PlanetilerConfig from(Arguments arguments) {
         0.1d),
       arguments.getBoolean("osm_lazy_reads",
         "Read OSM blocks from disk in worker threads",
+        false),
+      arguments.getBoolean("compact_db",
+        "Reduce the DB size by separating and deduping the tile data",
         false)
     );
   }