richardstartin commented on a change in pull request #6320:
URL: https://github.com/apache/incubator-pinot/pull/6320#discussion_r536911160
##########
File path:
pinot-core/src/main/java/org/apache/pinot/core/segment/creator/impl/inv/OffHeapBitmapInvertedIndexCreator.java
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@@ -181,33 +188,51 @@ public void seal()
}
// Create bitmaps from inverted index buffers and serialize them to file
- try (DataOutputStream offsetDataStream = new DataOutputStream(
- new BufferedOutputStream(new FileOutputStream(_invertedIndexFile)));
- FileOutputStream bitmapFileStream = new
FileOutputStream(_invertedIndexFile);
- DataOutputStream bitmapDataStream = new DataOutputStream(new
BufferedOutputStream(bitmapFileStream))) {
- int bitmapOffset = (_cardinality + 1) * Integer.BYTES;
- offsetDataStream.writeInt(bitmapOffset);
- bitmapFileStream.getChannel().position(bitmapOffset);
-
+ ByteBuffer offsetBuffer = null;
+ ByteBuffer bitmapBuffer = null;
+ try (FileChannel channel = new RandomAccessFile(_invertedIndexFile,
"rw").getChannel()) {
+ // map the offsets buffer
+ final int startOfBitmaps = (_cardinality + 1) * Integer.BYTES;
+ int bitmapOffset = startOfBitmaps;
+ offsetBuffer = channel.map(FileChannel.MapMode.READ_WRITE, 0,
bitmapOffset).order(LITTLE_ENDIAN);
+ offsetBuffer.putInt(reverseBytes(bitmapOffset));
+ RoaringBitmap[] bitmaps = new RoaringBitmap[_cardinality];
+ RoaringBitmapWriter<RoaringBitmap> writer = RoaringBitmapWriter.writer()
+ .initialCapacity(((_nextDocId - 1) >>> 16) / _cardinality).get();
Review comment:
This is just a heuristic that the keys of the bitmap will be evenly
distributed across the dictionary ids. It won't always be perfect, but is never
that bad. I can provide more justification.
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