curcur commented on a change in pull request #14893:
URL: https://github.com/apache/flink/pull/14893#discussion_r762717436
##########
File path:
flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBIncrementalCheckpointUtils.java
##########
@@ -122,30 +118,17 @@ private static void deleteRange(
RocksDB db,
List<ColumnFamilyHandle> columnFamilyHandles,
byte[] beginKeyBytes,
- byte[] endKeyBytes,
- @Nonnegative long writeBatchSize)
+ byte[] endKeyBytes)
throws RocksDBException {
for (ColumnFamilyHandle columnFamilyHandle : columnFamilyHandles) {
- try (ReadOptions readOptions = new ReadOptions();
- RocksIteratorWrapper iteratorWrapper =
- RocksDBOperationUtils.getRocksIterator(
- db, columnFamilyHandle, readOptions);
- RocksDBWriteBatchWrapper writeBatchWrapper =
- new RocksDBWriteBatchWrapper(db, writeBatchSize)) {
-
- iteratorWrapper.seek(beginKeyBytes);
-
- while (iteratorWrapper.isValid()) {
- final byte[] currentKey = iteratorWrapper.key();
- if (beforeThePrefixBytes(currentKey, endKeyBytes)) {
- writeBatchWrapper.remove(columnFamilyHandle,
currentKey);
- } else {
- break;
- }
- iteratorWrapper.next();
- }
- }
+ // Using RocksDB's deleteRange will take advantage of delete
+ // tombstones, which mark the range as deleted. There are
situations
+ // where tombstones can cause degraded performance, such as when
+ // too many tombstones are created.
+ //
+ //
https://github.com/facebook/rocksdb/blob/bcd32560dd5898956b9d24553c2bb3c1b1d2319f/include/rocksdb/db.h#L357-L371
Review comment:
Wondering whether this could be a problem (too many `tombstones`) for
Flink, given that the key group range is continuous and either left or right or
both of the key group range can be deleted during rescaling.
Besides, would the tombstones go away after compaction is done? Or if I miss
anything here?
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