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