richardstartin commented on a change in pull request #6320:
URL: https://github.com/apache/incubator-pinot/pull/6320#discussion_r536458126
##########
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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