Jackie-Jiang commented on a change in pull request #6320:
URL: https://github.com/apache/incubator-pinot/pull/6320#discussion_r537847693
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File path:
pinot-core/src/main/java/org/apache/pinot/core/segment/creator/impl/inv/OffHeapBitmapInvertedIndexCreator.java
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@@ -181,33 +184,45 @@ 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
+ int startOfBitmaps = (_cardinality + 1) * Integer.BYTES;
+ offsetBuffer = channel.map(FileChannel.MapMode.READ_WRITE, 0,
startOfBitmaps)
+ .order(ByteOrder.BIG_ENDIAN);
+ offsetBuffer.putInt(startOfBitmaps);
+ bitmapBuffer = channel.map(FileChannel.MapMode.READ_WRITE,
startOfBitmaps, Integer.MAX_VALUE - startOfBitmaps)
+ .order(ByteOrder.LITTLE_ENDIAN);
+ RoaringBitmapWriter<RoaringBitmap> writer =
RoaringBitmapWriter.writer().get();
Review comment:
The bitmap could be dense (when cardinality is very low), but won't be
contiguous. What is the old behavior? We don't explicitly call `runOptimize()`
on the `MutableRoaringBitmap`, will it perform RLE automatically? If not, we
can disable it here to keep the same behavior and have better performance.
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