mirror of https://github.com/facebook/rocksdb.git
Improve FragmentTombstones() speed by lazily initializing `seq_set_` (#10848)
Summary: FragmentedRangeTombstoneList has a member variable `seq_set_` that contains the sequence numbers of all range tombstones in a set. The set is constructed in `FragmentTombstones()` and is used only in `FragmentedRangeTombstoneList::ContainsRange()` which only happens during compaction. This PR moves the initialization of `seq_set_` to `FragmentedRangeTombstoneList::ContainsRange()`. This should speed up `FragmentTombstones()` when the range tombstone list is used for read/scan requests. Microbench shows the speed improvement to be ~45%. Pull Request resolved: https://github.com/facebook/rocksdb/pull/10848 Test Plan: - Existing tests and stress test: `python3 tools/db_crashtest.py whitebox --simple --verify_iterator_with_expected_state_one_in=5`. - Microbench: update `range_del_aggregator_bench` to benchmark speed of `FragmentTombstones()`: ``` ./range_del_aggregator_bench --num_range_tombstones=1000 --tombstone_start_upper_bound=50000000 --num_runs=10000 --tombstone_width_mean=200 --should_deletes_per_run=100 --use_compaction_range_del_aggregator=true Before this PR: ========================= Fragment Tombstones: 270.286 us AddTombstones: 1.28933 us ShouldDelete (first): 0.525528 us ShouldDelete (rest): 0.0797519 us After this PR: time to fragment tombstones is pushed to AddTombstones() which only happen during compaction. ========================= Fragment Tombstones: 149.879 us AddTombstones: 102.131 us ShouldDelete (first): 0.565871 us ShouldDelete (rest): 0.0729444 us ``` - db_bench: this should improve speed for fragmenting range tombstones for mutable memtable: ``` ./db_bench --benchmarks=readwhilewriting --writes_per_range_tombstone=100 --max_write_buffer_number=100 --min_write_buffer_number_to_merge=100 --writes=500000 --reads=250000 --disable_auto_compactions --max_num_range_tombstones=100000 --finish_after_writes --write_buffer_size=1073741824 --threads=25 Before this PR: readwhilewriting : 18.301 micros/op 1310445 ops/sec 4.769 seconds 6250000 operations; 28.1 MB/s (41001 of 250000 found) After this PR: readwhilewriting : 16.943 micros/op 1439376 ops/sec 4.342 seconds 6250000 operations; 23.8 MB/s (28977 of 250000 found) ``` Reviewed By: ajkr Differential Revision: D40646227 Pulled By: cbi42 fbshipit-source-id: ea471667edb258f67d01cfd828588e80a89e4083
This commit is contained in:
Changyu Bi
Facebook GitHub Bot
parent
fc74abb436
commit
7a95938899
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@ -587,8 +587,7 @@ FragmentedRangeTombstoneIterator* MemTable::NewRangeTombstoneIteratorInternal(
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auto* unfragmented_iter =
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new MemTableIterator(*this, read_options, nullptr /* arena */,
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true /* use_range_del_table */);
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cache->tombstones = std::make_unique<FragmentedRangeTombstoneList>(
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FragmentedRangeTombstoneList(
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cache->tombstones.reset(new FragmentedRangeTombstoneList(
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std::unique_ptr<InternalIterator>(unfragmented_iter),
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comparator_.comparator));
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cache->initialized.store(true, std::memory_order_release);
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@ -54,12 +54,17 @@ DEFINE_int32(should_deletes_per_run, 1, "number of ShouldDelete calls per run");
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DEFINE_int32(add_tombstones_per_run, 1,
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"number of AddTombstones calls per run");
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DEFINE_bool(use_compaction_range_del_aggregator, false,
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"Whether to use CompactionRangeDelAggregator. Default is to use "
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"ReadRangeDelAggregator.");
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namespace {
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struct Stats {
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uint64_t time_add_tombstones = 0;
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uint64_t time_first_should_delete = 0;
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uint64_t time_rest_should_delete = 0;
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uint64_t time_fragment_tombstones = 0;
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};
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std::ostream& operator<<(std::ostream& os, const Stats& s) {
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@ -67,6 +72,10 @@ std::ostream& operator<<(std::ostream& os, const Stats& s) {
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fmt_holder.copyfmt(os);
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os << std::left;
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os << std::setw(25) << "Fragment Tombstones: "
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<< s.time_fragment_tombstones /
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(FLAGS_add_tombstones_per_run * FLAGS_num_runs * 1.0e3)
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<< " us\n";
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os << std::setw(25) << "AddTombstones: "
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<< s.time_add_tombstones /
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(FLAGS_add_tombstones_per_run * FLAGS_num_runs * 1.0e3)
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@ -186,10 +195,17 @@ int main(int argc, char** argv) {
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FLAGS_num_range_tombstones);
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}
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auto mode = ROCKSDB_NAMESPACE::RangeDelPositioningMode::kForwardTraversal;
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std::vector<ROCKSDB_NAMESPACE::SequenceNumber> snapshots{0};
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for (int i = 0; i < FLAGS_num_runs; i++) {
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ROCKSDB_NAMESPACE::ReadRangeDelAggregator range_del_agg(
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&icmp, ROCKSDB_NAMESPACE::kMaxSequenceNumber /* upper_bound */);
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std::unique_ptr<ROCKSDB_NAMESPACE::RangeDelAggregator> range_del_agg =
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nullptr;
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if (FLAGS_use_compaction_range_del_aggregator) {
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range_del_agg.reset(new ROCKSDB_NAMESPACE::CompactionRangeDelAggregator(
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&icmp, snapshots));
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} else {
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range_del_agg.reset(new ROCKSDB_NAMESPACE::ReadRangeDelAggregator(
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&icmp, ROCKSDB_NAMESPACE::kMaxSequenceNumber /* upper_bound */));
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}
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std::vector<
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std::unique_ptr<ROCKSDB_NAMESPACE::FragmentedRangeTombstoneList> >
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@ -207,12 +223,16 @@ int main(int argc, char** argv) {
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ROCKSDB_NAMESPACE::PersistentRangeTombstone(
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ROCKSDB_NAMESPACE::Key(start), ROCKSDB_NAMESPACE::Key(end), j);
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}
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auto iter =
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ROCKSDB_NAMESPACE::MakeRangeDelIterator(persistent_range_tombstones);
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ROCKSDB_NAMESPACE::StopWatchNano stop_watch_fragment_tombstones(
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clock, true /* auto_start */);
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fragmented_range_tombstone_lists.emplace_back(
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new ROCKSDB_NAMESPACE::FragmentedRangeTombstoneList(
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ROCKSDB_NAMESPACE::MakeRangeDelIterator(
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persistent_range_tombstones),
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icmp));
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std::move(iter), icmp, FLAGS_use_compaction_range_del_aggregator,
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snapshots));
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stats.time_fragment_tombstones +=
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stop_watch_fragment_tombstones.ElapsedNanos();
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std::unique_ptr<ROCKSDB_NAMESPACE::FragmentedRangeTombstoneIterator>
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fragmented_range_del_iter(
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new ROCKSDB_NAMESPACE::FragmentedRangeTombstoneIterator(
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@ -221,7 +241,7 @@ int main(int argc, char** argv) {
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ROCKSDB_NAMESPACE::StopWatchNano stop_watch_add_tombstones(
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clock, true /* auto_start */);
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range_del_agg.AddTombstones(std::move(fragmented_range_del_iter));
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range_del_agg->AddTombstones(std::move(fragmented_range_del_iter));
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stats.time_add_tombstones += stop_watch_add_tombstones.ElapsedNanos();
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}
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@ -238,7 +258,7 @@ int main(int argc, char** argv) {
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ROCKSDB_NAMESPACE::StopWatchNano stop_watch_should_delete(
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clock, true /* auto_start */);
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range_del_agg.ShouldDelete(parsed_key, mode);
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range_del_agg->ShouldDelete(parsed_key, mode);
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uint64_t call_time = stop_watch_should_delete.ElapsedNanos();
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if (j == 0) {
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@ -156,7 +156,6 @@ void FragmentedRangeTombstoneList::FragmentTombstones(
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if (seq <= next_snapshot) {
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// This seqnum is visible by a lower snapshot.
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tombstone_seqs_.push_back(seq);
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seq_set_.insert(seq);
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auto upper_bound_it =
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std::lower_bound(snapshots.begin(), snapshots.end(), seq);
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if (upper_bound_it == snapshots.begin()) {
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@ -173,7 +172,6 @@ void FragmentedRangeTombstoneList::FragmentTombstones(
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// The fragmentation is being done for reads, so preserve all seqnums.
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tombstone_seqs_.insert(tombstone_seqs_.end(), seqnums_to_flush.begin(),
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seqnums_to_flush.end());
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seq_set_.insert(seqnums_to_flush.begin(), seqnums_to_flush.end());
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if (ts_sz) {
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tombstone_timestamps_.insert(tombstone_timestamps_.end(),
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timestamps_to_flush.begin(),
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@ -258,15 +256,20 @@ void FragmentedRangeTombstoneList::FragmentTombstones(
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}
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bool FragmentedRangeTombstoneList::ContainsRange(SequenceNumber lower,
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SequenceNumber upper) const {
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SequenceNumber upper) {
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std::call_once(seq_set_init_once_flag_, [this]() {
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for (auto s : tombstone_seqs_) {
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seq_set_.insert(s);
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}
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});
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auto seq_it = seq_set_.lower_bound(lower);
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return seq_it != seq_set_.end() && *seq_it <= upper;
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}
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FragmentedRangeTombstoneIterator::FragmentedRangeTombstoneIterator(
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const FragmentedRangeTombstoneList* tombstones,
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const InternalKeyComparator& icmp, SequenceNumber _upper_bound,
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const Slice* ts_upper_bound, SequenceNumber _lower_bound)
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FragmentedRangeTombstoneList* tombstones, const InternalKeyComparator& icmp,
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SequenceNumber _upper_bound, const Slice* ts_upper_bound,
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SequenceNumber _lower_bound)
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: tombstone_start_cmp_(icmp.user_comparator()),
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tombstone_end_cmp_(icmp.user_comparator()),
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icmp_(&icmp),
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@ -280,7 +283,7 @@ FragmentedRangeTombstoneIterator::FragmentedRangeTombstoneIterator(
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}
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FragmentedRangeTombstoneIterator::FragmentedRangeTombstoneIterator(
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const std::shared_ptr<const FragmentedRangeTombstoneList>& tombstones,
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const std::shared_ptr<FragmentedRangeTombstoneList>& tombstones,
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const InternalKeyComparator& icmp, SequenceNumber _upper_bound,
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const Slice* ts_upper_bound, SequenceNumber _lower_bound)
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: tombstone_start_cmp_(icmp.user_comparator()),
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@ -84,7 +84,9 @@ struct FragmentedRangeTombstoneList {
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// Returns true if the stored tombstones contain with one with a sequence
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// number in [lower, upper].
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bool ContainsRange(SequenceNumber lower, SequenceNumber upper) const;
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// This method is not const as it internally lazy initialize a set of
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// sequence numbers (`seq_set_`).
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bool ContainsRange(SequenceNumber lower, SequenceNumber upper);
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uint64_t num_unfragmented_tombstones() const {
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return num_unfragmented_tombstones_;
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@ -113,6 +115,7 @@ struct FragmentedRangeTombstoneList {
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std::vector<RangeTombstoneStack> tombstones_;
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std::vector<SequenceNumber> tombstone_seqs_;
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std::vector<Slice> tombstone_timestamps_;
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std::once_flag seq_set_init_once_flag_;
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std::set<SequenceNumber> seq_set_;
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std::list<std::string> pinned_slices_;
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PinnedIteratorsManager pinned_iters_mgr_;
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@ -131,12 +134,13 @@ struct FragmentedRangeTombstoneList {
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// tombstone collapsing is always O(n log n).
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class FragmentedRangeTombstoneIterator : public InternalIterator {
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public:
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FragmentedRangeTombstoneIterator(FragmentedRangeTombstoneList* tombstones,
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const InternalKeyComparator& icmp,
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SequenceNumber upper_bound,
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const Slice* ts_upper_bound = nullptr,
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SequenceNumber lower_bound = 0);
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FragmentedRangeTombstoneIterator(
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const FragmentedRangeTombstoneList* tombstones,
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const InternalKeyComparator& icmp, SequenceNumber upper_bound,
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const Slice* ts_upper_bound = nullptr, SequenceNumber lower_bound = 0);
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FragmentedRangeTombstoneIterator(
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const std::shared_ptr<const FragmentedRangeTombstoneList>& tombstones,
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const std::shared_ptr<FragmentedRangeTombstoneList>& tombstones,
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const InternalKeyComparator& icmp, SequenceNumber upper_bound,
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const Slice* ts_upper_bound = nullptr, SequenceNumber lower_bound = 0);
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FragmentedRangeTombstoneIterator(
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@ -311,9 +315,9 @@ class FragmentedRangeTombstoneIterator : public InternalIterator {
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const RangeTombstoneStackEndComparator tombstone_end_cmp_;
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const InternalKeyComparator* icmp_;
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const Comparator* ucmp_;
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std::shared_ptr<const FragmentedRangeTombstoneList> tombstones_ref_;
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std::shared_ptr<FragmentedRangeTombstoneList> tombstones_ref_;
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std::shared_ptr<FragmentedRangeTombstoneListCache> tombstones_cache_ref_;
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const FragmentedRangeTombstoneList* tombstones_;
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FragmentedRangeTombstoneList* tombstones_;
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SequenceNumber upper_bound_;
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SequenceNumber lower_bound_;
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// Only consider timestamps <= ts_upper_bound_.
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@ -597,7 +597,7 @@ struct BlockBasedTable::Rep {
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bool prefix_filtering;
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std::shared_ptr<const SliceTransform> table_prefix_extractor;
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std::shared_ptr<const FragmentedRangeTombstoneList> fragmented_range_dels;
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std::shared_ptr<FragmentedRangeTombstoneList> fragmented_range_dels;
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// If global_seqno is used, all Keys in this file will have the same
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// seqno with value `global_seqno`.
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