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Posted to commits@pinot.apache.org by GitBox <gi...@apache.org> on 2020/12/05 00:21:59 UTC
[GitHub] [incubator-pinot] richardstartin commented on a change in pull request #6320: More efficient use of RoaringBitmap in OnHeapBitmapInvertedIndexCreator
richardstartin commented on a change in pull request #6320:
URL: https://github.com/apache/incubator-pinot/pull/6320#discussion_r536458126
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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 +188,49 @@ 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));
+ MutableRoaringBitmap[] bitmaps = new MutableRoaringBitmap[_cardinality];
Review comment:
This is a allocation, but it's offset against the 16KB in stream buffers no longer allocated, and is a lot smaller than the bitmaps being materialised here anyway. This pattern where bitmaps are allocated just to obtain their serialized bytes could probably be supported by roaringbitmap without actually creating the intermediate bitmaps without much complication.
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