mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-26 07:30:54 +00:00
45 lines
1.9 KiB
C
45 lines
1.9 KiB
C
|
// Copyright (c) Meta Platforms, Inc. and affiliates.
|
||
|
|
//
|
||
|
|
// This source code is licensed under both the GPLv2 (found in the
|
||
|
|
// COPYING file in the root directory) and Apache 2.0 License
|
||
|
|
// (found in the LICENSE.Apache file in the root directory).
|
||
|
|
|
||
|
|
#pragma once
|
||
|
|
|
||
|
|
#include "db/range_del_aggregator.h"
|
||
|
|
#include "rocksdb/slice.h"
|
||
|
|
#include "rocksdb/types.h"
|
||
|
|
#include "table/merging_iterator.h"
|
||
|
|
|
||
|
|
namespace ROCKSDB_NAMESPACE {
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This is a simplified version of MergingIterator and is specifically used for
|
||
|
|
* compaction. It merges the input `children` iterators into a sorted stream of
|
||
|
|
* keys. Range tombstone start keys are also emitted to prevent oversize
|
||
|
|
* compactions. For example, consider an L1 file with content [a, b), y, z,
|
||
|
|
* where [a, b) is a range tombstone and y and z are point keys. This could
|
||
|
|
* cause an oversize compaction as it can overlap with a wide range of key space
|
||
|
|
* in L2.
|
||
|
|
*
|
||
|
|
* CompactionMergingIterator emits range tombstone start keys from each LSM
|
||
|
|
* level's range tombstone iterator, and for each range tombstone
|
||
|
|
* [start,end)@seqno, the key will be start@seqno with op_type
|
||
|
|
* kTypeRangeDeletion unless truncated at file boundary (see detail in
|
||
|
|
* TruncatedRangeDelIterator::start_key()).
|
||
|
|
*
|
||
|
|
* Caller should use CompactionMergingIterator::IsDeleteRangeSentinelKey() to
|
||
|
|
* check if the current key is a range tombstone key.
|
||
|
|
* TODO(cbi): IsDeleteRangeSentinelKey() is used for two kinds of keys at
|
||
|
|
* different layers: file boundary and range tombstone keys. Separate them into
|
||
|
|
* two APIs for clarity.
|
||
|
|
*/
|
||
|
|
class CompactionMergingIterator;
|
||
|
|
|
||
|
|
InternalIterator* NewCompactionMergingIterator(
|
||
|
|
const InternalKeyComparator* comparator, InternalIterator** children, int n,
|
||
|
|
std::vector<std::pair<TruncatedRangeDelIterator*,
|
||
|
|
TruncatedRangeDelIterator***>>& range_tombstone_iters,
|
||
|
|
Arena* arena = nullptr);
|
||
|
|
} // namespace ROCKSDB_NAMESPACE
|