clone smallest bitmap, adjust naive/workshy and thresholds

RoaringBitmap · Jan 2, 2023 · cc67655 · cc67655
1 parent 7056910
commit cc67655
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Showing 2 changed files with 28 additions and 10 deletions.
diff --git a/RoaringBitmap/src/main/java/org/roaringbitmap/FastAggregation.java b/RoaringBitmap/src/main/java/org/roaringbitmap/FastAggregation.java
@@ -35,7 +35,7 @@ public static RoaringBitmap and(Iterator<? extends RoaringBitmap> bitmaps) {
    * @return aggregated bitmap
    */
   public static RoaringBitmap and(RoaringBitmap... bitmaps) {
-    if (bitmaps.length > 2) {
+    if (bitmaps.length > 10) {
       return workShyAnd(new long[1024], bitmaps);
     }
     return naive_and(bitmaps);
@@ -49,7 +49,7 @@ public static RoaringBitmap and(RoaringBitmap... bitmaps) {
    * @return aggregated bitmap
    */
   public static RoaringBitmap and(long[] aggregationBuffer, RoaringBitmap... bitmaps) {
-    if (bitmaps.length > 2) {
+    if (bitmaps.length > 10) {
       if(aggregationBuffer.length < 1024) {
         throw new IllegalArgumentException("buffer should have at least 1024 elements.");
       }
@@ -329,9 +329,18 @@ public static RoaringBitmap naive_and(RoaringBitmap... bitmaps) {
     if (bitmaps.length == 0) {
       return new RoaringBitmap();
     }
-    RoaringBitmap answer = bitmaps[0].clone();
-    for (int k = 1; k < bitmaps.length && !answer.isEmpty(); ++k) {
-      answer.and(bitmaps[k]);
+    RoaringBitmap smallest = bitmaps[0];
+    for (int i = 1; i < bitmaps.length; i++) {
+      RoaringBitmap bitmap = bitmaps[i];
+      if (bitmap.highLowContainer.size() < smallest.highLowContainer.size()) {
+        smallest = bitmap;
+      }
+    }
+    RoaringBitmap answer = smallest.clone();
+    for (int k = 0; k < bitmaps.length && !answer.isEmpty(); ++k) {
+      if (bitmaps[k] != smallest) {
+        answer.and(bitmaps[k]);
+      }
     }
     return answer;
   }

diff --git a/RoaringBitmap/src/main/java/org/roaringbitmap/buffer/BufferFastAggregation.java b/RoaringBitmap/src/main/java/org/roaringbitmap/buffer/BufferFastAggregation.java
@@ -26,7 +26,7 @@ public final class BufferFastAggregation {
    * @return aggregated bitmap
    */
   public static MutableRoaringBitmap and(ImmutableRoaringBitmap... bitmaps) {
-    if (bitmaps.length > 2) {
+    if (bitmaps.length > 10) {
       return workShyAnd(new long[1024], bitmaps);
     }
     return naive_and(bitmaps);
@@ -42,7 +42,7 @@ public static MutableRoaringBitmap and(ImmutableRoaringBitmap... bitmaps) {
    */
   public static MutableRoaringBitmap and(long[] aggregationBuffer,
                                          ImmutableRoaringBitmap... bitmaps) {
-    if (bitmaps.length > 2) {
+    if (bitmaps.length > 10) {
       if(aggregationBuffer.length < 1024) {
         throw new IllegalArgumentException("buffer should have at least 1024 elements.");
       }
@@ -348,9 +348,18 @@ public static MutableRoaringBitmap naive_and(ImmutableRoaringBitmap... bitmaps)
     MutableRoaringBitmap answer;
 
     if (bitmaps.length > 0) {
-      answer = (bitmaps[0]).toMutableRoaringBitmap();
-      for (int k = 1; k < bitmaps.length; ++k) {
-        answer = ImmutableRoaringBitmap.and(answer, bitmaps[k]);
+      ImmutableRoaringBitmap smallest = bitmaps[0];
+      for (int i = 1; i < bitmaps.length; i++) {
+        ImmutableRoaringBitmap bitmap = bitmaps[i];
+        if (bitmap.highLowContainer.size() < smallest.highLowContainer.size()) {
+          smallest = bitmap;
+        }
+      }
+      answer = (smallest).toMutableRoaringBitmap();
+      for (ImmutableRoaringBitmap bitmap : bitmaps) {
+        if (bitmap != smallest) {
+          answer.and(bitmap);
+        }
       }
     } else {
       answer = new MutableRoaringBitmap();