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rocksdb/db/compaction/compaction_outputs.cc

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// 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/compaction/compaction_outputs.h"
#include "db/builder.h"
namespace ROCKSDB_NAMESPACE {
void CompactionOutputs::NewBuilder(const TableBuilderOptions& tboptions) {
builder_.reset(NewTableBuilder(tboptions, file_writer_.get()));
}
Status CompactionOutputs::Finish(
const Status& intput_status,
const SeqnoToTimeMapping& seqno_to_time_mapping) {
FileMetaData* meta = GetMetaData();
assert(meta != nullptr);
Status s = intput_status;
if (s.ok()) {
std::string seqno_to_time_mapping_str;
seqno_to_time_mapping.Encode(
seqno_to_time_mapping_str, meta->fd.smallest_seqno,
meta->fd.largest_seqno, meta->file_creation_time);
builder_->SetSeqnoTimeTableProperties(seqno_to_time_mapping_str,
meta->oldest_ancester_time);
s = builder_->Finish();
} else {
builder_->Abandon();
}
Status io_s = builder_->io_status();
if (s.ok()) {
s = io_s;
} else {
io_s.PermitUncheckedError();
}
const uint64_t current_bytes = builder_->FileSize();
if (s.ok()) {
meta->fd.file_size = current_bytes;
meta->tail_size = builder_->GetTailSize();
meta->marked_for_compaction = builder_->NeedCompact();
meta->user_defined_timestamps_persisted = static_cast<bool>(
builder_->GetTableProperties().user_defined_timestamps_persisted);
}
current_output().finished = true;
stats_.bytes_written += current_bytes;
stats_.num_output_files = outputs_.size();
return s;
}
IOStatus CompactionOutputs::WriterSyncClose(const Status& input_status,
SystemClock* clock,
Statistics* statistics,
bool use_fsync) {
IOStatus io_s;
if (input_status.ok()) {
StopWatch sw(clock, statistics, COMPACTION_OUTFILE_SYNC_MICROS);
io_s = file_writer_->Sync(use_fsync);
}
if (input_status.ok() && io_s.ok()) {
io_s = file_writer_->Close();
}
if (input_status.ok() && io_s.ok()) {
FileMetaData* meta = GetMetaData();
meta->file_checksum = file_writer_->GetFileChecksum();
meta->file_checksum_func_name = file_writer_->GetFileChecksumFuncName();
}
file_writer_.reset();
return io_s;
}
bool CompactionOutputs::UpdateFilesToCutForTTLStates(
const Slice& internal_key) {
if (!files_to_cut_for_ttl_.empty()) {
const InternalKeyComparator* icmp =
&compaction_->column_family_data()->internal_comparator();
if (cur_files_to_cut_for_ttl_ != -1) {
// Previous key is inside the range of a file
if (icmp->Compare(internal_key,
files_to_cut_for_ttl_[cur_files_to_cut_for_ttl_]
->largest.Encode()) > 0) {
next_files_to_cut_for_ttl_ = cur_files_to_cut_for_ttl_ + 1;
cur_files_to_cut_for_ttl_ = -1;
return true;
}
} else {
// Look for the key position
while (next_files_to_cut_for_ttl_ <
static_cast<int>(files_to_cut_for_ttl_.size())) {
if (icmp->Compare(internal_key,
files_to_cut_for_ttl_[next_files_to_cut_for_ttl_]
->smallest.Encode()) >= 0) {
if (icmp->Compare(internal_key,
files_to_cut_for_ttl_[next_files_to_cut_for_ttl_]
->largest.Encode()) <= 0) {
// With in the current file
cur_files_to_cut_for_ttl_ = next_files_to_cut_for_ttl_;
return true;
}
// Beyond the current file
next_files_to_cut_for_ttl_++;
} else {
// Still fall into the gap
break;
}
}
}
}
return false;
}
size_t CompactionOutputs::UpdateGrandparentBoundaryInfo(
const Slice& internal_key) {
size_t curr_key_boundary_switched_num = 0;
const std::vector<FileMetaData*>& grandparents = compaction_->grandparents();
if (grandparents.empty()) {
return curr_key_boundary_switched_num;
}
const Comparator* ucmp = compaction_->column_family_data()->user_comparator();
// Move the grandparent_index_ to the file containing the current user_key.
// If there are multiple files containing the same user_key, make sure the
// index points to the last file containing the key.
while (grandparent_index_ < grandparents.size()) {
if (being_grandparent_gap_) {
if (sstableKeyCompare(ucmp, internal_key,
grandparents[grandparent_index_]->smallest) < 0) {
break;
}
if (seen_key_) {
curr_key_boundary_switched_num++;
grandparent_overlapped_bytes_ +=
grandparents[grandparent_index_]->fd.GetFileSize();
grandparent_boundary_switched_num_++;
}
being_grandparent_gap_ = false;
} else {
int cmp_result = sstableKeyCompare(
ucmp, internal_key, grandparents[grandparent_index_]->largest);
// If it's same key, make sure grandparent_index_ is pointing to the last
// one.
if (cmp_result < 0 ||
(cmp_result == 0 &&
(grandparent_index_ == grandparents.size() - 1 ||
sstableKeyCompare(ucmp, internal_key,
grandparents[grandparent_index_ + 1]->smallest) <
0))) {
break;
}
if (seen_key_) {
curr_key_boundary_switched_num++;
grandparent_boundary_switched_num_++;
}
being_grandparent_gap_ = true;
grandparent_index_++;
}
}
// If the first key is in the middle of a grandparent file, adding it to the
// overlap
if (!seen_key_ && !being_grandparent_gap_) {
assert(grandparent_overlapped_bytes_ == 0);
grandparent_overlapped_bytes_ =
GetCurrentKeyGrandparentOverlappedBytes(internal_key);
}
seen_key_ = true;
return curr_key_boundary_switched_num;
}
uint64_t CompactionOutputs::GetCurrentKeyGrandparentOverlappedBytes(
const Slice& internal_key) const {
// no overlap with any grandparent file
if (being_grandparent_gap_) {
return 0;
}
uint64_t overlapped_bytes = 0;
const std::vector<FileMetaData*>& grandparents = compaction_->grandparents();
const Comparator* ucmp = compaction_->column_family_data()->user_comparator();
InternalKey ikey;
ikey.DecodeFrom(internal_key);
#ifndef NDEBUG
// make sure the grandparent_index_ is pointing to the last files containing
// the current key.
int cmp_result =
sstableKeyCompare(ucmp, ikey, grandparents[grandparent_index_]->largest);
assert(
cmp_result < 0 ||
(cmp_result == 0 &&
(grandparent_index_ == grandparents.size() - 1 ||
sstableKeyCompare(
ucmp, ikey, grandparents[grandparent_index_ + 1]->smallest) < 0)));
assert(sstableKeyCompare(ucmp, ikey,
grandparents[grandparent_index_]->smallest) >= 0);
#endif
overlapped_bytes += grandparents[grandparent_index_]->fd.GetFileSize();
// go backwards to find all overlapped files, one key can overlap multiple
// files. In the following example, if the current output key is `c`, and one
// compaction file was cut before `c`, current `c` can overlap with 3 files:
// [a b] [c...
// [b, b] [c, c] [c, c] [c, d]
for (int64_t i = static_cast<int64_t>(grandparent_index_) - 1;
i >= 0 && sstableKeyCompare(ucmp, ikey, grandparents[i]->largest) == 0;
i--) {
overlapped_bytes += grandparents[i]->fd.GetFileSize();
}
return overlapped_bytes;
}
bool CompactionOutputs::ShouldStopBefore(const CompactionIterator& c_iter) {
assert(c_iter.Valid());
const Slice& internal_key = c_iter.key();
#ifndef NDEBUG
bool should_stop = false;
std::pair<bool*, const Slice> p{&should_stop, internal_key};
TEST_SYNC_POINT_CALLBACK(
"CompactionOutputs::ShouldStopBefore::manual_decision", (void*)&p);
if (should_stop) {
return true;
}
#endif // NDEBUG
const uint64_t previous_overlapped_bytes = grandparent_overlapped_bytes_;
const InternalKeyComparator* icmp =
&compaction_->column_family_data()->internal_comparator();
size_t num_grandparent_boundaries_crossed = 0;
bool should_stop_for_ttl = false;
// Always update grandparent information like overlapped file number, size
// etc., and TTL states.
// If compaction_->output_level() == 0, there is no need to update grandparent
// info, and that `grandparent` should be empty.
if (compaction_->output_level() > 0) {
num_grandparent_boundaries_crossed =
UpdateGrandparentBoundaryInfo(internal_key);
should_stop_for_ttl = UpdateFilesToCutForTTLStates(internal_key);
}
if (!HasBuilder()) {
return false;
}
if (should_stop_for_ttl) {
return true;
}
// If there's user defined partitioner, check that first
if (partitioner_ && partitioner_->ShouldPartition(PartitionerRequest(
last_key_for_partitioner_, c_iter.user_key(),
current_output_file_size_)) == kRequired) {
return true;
}
// files output to Level 0 won't be split
if (compaction_->output_level() == 0) {
return false;
}
// reach the max file size
if (current_output_file_size_ >= compaction_->max_output_file_size()) {
return true;
}
// Check if it needs to split for RoundRobin
// Invalid local_output_split_key indicates that we do not need to split
if (local_output_split_key_ != nullptr && !is_split_) {
// Split occurs when the next key is larger than/equal to the cursor
if (icmp->Compare(internal_key, local_output_split_key_->Encode()) >= 0) {
is_split_ = true;
return true;
}
}
// only check if the current key is going to cross the grandparents file
// boundary (either the file beginning or ending).
if (num_grandparent_boundaries_crossed > 0) {
// Cut the file before the current key if the size of the current output
// file + its overlapped grandparent files is bigger than
// max_compaction_bytes. Which is to prevent future bigger than
// max_compaction_bytes compaction from the current output level.
if (grandparent_overlapped_bytes_ + current_output_file_size_ >
compaction_->max_compaction_bytes()) {
return true;
}
// Cut the file if including the key is going to add a skippable file on
// the grandparent level AND its size is reasonably big (1/8 of target file
// size). For example, if it's compacting the files L0 + L1:
// L0: [1, 21]
// L1: [3, 23]
// L2: [2, 4] [11, 15] [22, 24]
// Without this break, it will output as:
// L1: [1,3, 21,23]
// With this break, it will output as (assuming [11, 15] at L2 is bigger
// than 1/8 of target size):
// L1: [1,3] [21,23]
// Then for the future compactions, [11,15] won't be included.
// For random datasets (either evenly distributed or skewed), it rarely
// triggers this condition, but if the user is adding 2 different datasets
// without any overlap, it may likely happen.
// More details, check PR #1963
const size_t num_skippable_boundaries_crossed =
being_grandparent_gap_ ? 2 : 3;
if (compaction_->immutable_options()->compaction_style ==
kCompactionStyleLevel &&
compaction_->immutable_options()->level_compaction_dynamic_file_size &&
num_grandparent_boundaries_crossed >=
num_skippable_boundaries_crossed &&
grandparent_overlapped_bytes_ - previous_overlapped_bytes >
compaction_->target_output_file_size() / 8) {
return true;
}
// Pre-cut the output file if it's reaching a certain size AND it's at the
// boundary of a grandparent file. It can reduce the future compaction size,
// the cost is having smaller files.
// The pre-cut size threshold is based on how many grandparent boundaries
// it has seen before. Basically, if it has seen no boundary at all, then it
// will pre-cut at 50% target file size. Every boundary it has seen
// increases the threshold by 5%, max at 90%, which it will always cut.
// The idea is based on if it has seen more boundaries before, it will more
// likely to see another boundary (file cutting opportunity) before the
// target file size. The test shows it can generate larger files than a
// static threshold like 75% and has a similar write amplification
// improvement.
if (compaction_->immutable_options()->compaction_style ==
kCompactionStyleLevel &&
compaction_->immutable_options()->level_compaction_dynamic_file_size &&
current_output_file_size_ >=
((compaction_->target_output_file_size() + 99) / 100) *
(50 + std::min(grandparent_boundary_switched_num_ * 5,
size_t{40}))) {
return true;
}
}
return false;
}
Status CompactionOutputs::AddToOutput(
const CompactionIterator& c_iter,
const CompactionFileOpenFunc& open_file_func,
const CompactionFileCloseFunc& close_file_func) {
Status s;
bool is_range_del = c_iter.IsDeleteRangeSentinelKey();
if (is_range_del && compaction_->bottommost_level()) {
// We don't consider range tombstone for bottommost level since:
// 1. there is no grandparent and hence no overlap to consider
// 2. range tombstone may be dropped at bottommost level.
return s;
}
const Slice& key = c_iter.key();
if (ShouldStopBefore(c_iter) && HasBuilder()) {
s = close_file_func(*this, c_iter.InputStatus(), key);
if (!s.ok()) {
return s;
}
// reset grandparent information
grandparent_boundary_switched_num_ = 0;
grandparent_overlapped_bytes_ =
GetCurrentKeyGrandparentOverlappedBytes(key);
if (UNLIKELY(is_range_del)) {
// lower bound for this new output file, this is needed as the lower bound
// does not come from the smallest point key in this case.
range_tombstone_lower_bound_.DecodeFrom(key);
} else {
range_tombstone_lower_bound_.Clear();
}
}
// Open output file if necessary
if (!HasBuilder()) {
s = open_file_func(*this);
if (!s.ok()) {
return s;
}
}
// c_iter may emit range deletion keys, so update `last_key_for_partitioner_`
// here before returning below when `is_range_del` is true
if (partitioner_) {
last_key_for_partitioner_.assign(c_iter.user_key().data_,
c_iter.user_key().size_);
}
if (UNLIKELY(is_range_del)) {
return s;
}
assert(builder_ != nullptr);
const Slice& value = c_iter.value();
s = current_output().validator.Add(key, value);
if (!s.ok()) {
return s;
}
builder_->Add(key, value);
stats_.num_output_records++;
current_output_file_size_ = builder_->EstimatedFileSize();
if (blob_garbage_meter_) {
s = blob_garbage_meter_->ProcessOutFlow(key, value);
}
if (!s.ok()) {
return s;
}
const ParsedInternalKey& ikey = c_iter.ikey();
s = current_output().meta.UpdateBoundaries(key, value, ikey.sequence,
ikey.type);
return s;
}
namespace {
void SetMaxSeqAndTs(InternalKey& internal_key, const Slice& user_key,
const size_t ts_sz) {
if (ts_sz) {
static constexpr char kTsMax[] = "\xff\xff\xff\xff\xff\xff\xff\xff\xff";
if (ts_sz <= strlen(kTsMax)) {
internal_key = InternalKey(user_key, kMaxSequenceNumber,
kTypeRangeDeletion, Slice(kTsMax, ts_sz));
} else {
internal_key =
InternalKey(user_key, kMaxSequenceNumber, kTypeRangeDeletion,
std::string(ts_sz, '\xff'));
}
} else {
internal_key.Set(user_key, kMaxSequenceNumber, kTypeRangeDeletion);
}
}
} // namespace
Status CompactionOutputs::AddRangeDels(
const Slice* comp_start_user_key, const Slice* comp_end_user_key,
CompactionIterationStats& range_del_out_stats, bool bottommost_level,
const InternalKeyComparator& icmp, SequenceNumber earliest_snapshot,
const Slice& next_table_min_key, const std::string& full_history_ts_low) {
// The following example does not happen since
// CompactionOutput::ShouldStopBefore() always return false for the first
// point key. But we should consider removing this dependency. Suppose for the
// first compaction output file,
// - next_table_min_key.user_key == comp_start_user_key
// - no point key is in the output file
// - there is a range tombstone @seqno to be added that covers
// comp_start_user_key
// Then meta.smallest will be set to comp_start_user_key@seqno
// and meta.largest will be set to comp_start_user_key@kMaxSequenceNumber
// which violates the assumption that meta.smallest should be <= meta.largest.
assert(HasRangeDel());
FileMetaData& meta = current_output().meta;
const Comparator* ucmp = icmp.user_comparator();
InternalKey lower_bound_buf, upper_bound_buf;
Slice lower_bound_guard, upper_bound_guard;
std::string smallest_user_key;
const Slice *lower_bound, *upper_bound;
// We first determine the internal key lower_bound and upper_bound for
// this output file. All and only range tombstones that overlap with
// [lower_bound, upper_bound] should be added to this file. File
// boundaries (meta.smallest/largest) should be updated accordingly when
// extended by range tombstones.
size_t output_size = outputs_.size();
if (output_size == 1) {
// This is the first file in the subcompaction.
//
// When outputting a range tombstone that spans a subcompaction boundary,
// the files on either side of that boundary need to include that
// boundary's user key. Otherwise, the spanning range tombstone would lose
// coverage.
//
// To achieve this while preventing files from overlapping in internal key
// (an LSM invariant violation), we allow the earlier file to include the
// boundary user key up to `kMaxSequenceNumber,kTypeRangeDeletion`. The
// later file can begin at the boundary user key at the newest key version
// it contains. At this point that version number is unknown since we have
// not processed the range tombstones yet, so permit any version. Same story
// applies to timestamp, and a non-nullptr `comp_start_user_key` should have
// `kMaxTs` here, which similarly permits any timestamp.
if (comp_start_user_key) {
lower_bound_buf.Set(*comp_start_user_key, kMaxSequenceNumber,
kTypeRangeDeletion);
lower_bound_guard = lower_bound_buf.Encode();
lower_bound = &lower_bound_guard;
} else {
lower_bound = nullptr;
}
} else {
// For subsequent output tables, only include range tombstones from min
// key onwards since the previous file was extended to contain range
// tombstones falling before min key.
if (range_tombstone_lower_bound_.size() > 0) {
assert(meta.smallest.size() == 0 ||
icmp.Compare(range_tombstone_lower_bound_, meta.smallest) < 0);
lower_bound_guard = range_tombstone_lower_bound_.Encode();
} else {
assert(meta.smallest.size() > 0);
lower_bound_guard = meta.smallest.Encode();
}
lower_bound = &lower_bound_guard;
}
const size_t ts_sz = ucmp->timestamp_size();
if (next_table_min_key.empty()) {
// Last file of the subcompaction.
if (comp_end_user_key) {
upper_bound_buf.Set(*comp_end_user_key, kMaxSequenceNumber,
kTypeRangeDeletion);
upper_bound_guard = upper_bound_buf.Encode();
upper_bound = &upper_bound_guard;
} else {
upper_bound = nullptr;
}
} else {
// There is another file coming whose coverage will begin at
// `next_table_min_key`. The current file needs to extend range tombstone
// coverage through its own keys (through `meta.largest`) and through user
// keys preceding `next_table_min_key`'s user key.
ParsedInternalKey next_table_min_key_parsed;
ParseInternalKey(next_table_min_key, &next_table_min_key_parsed,
false /* log_err_key */)
.PermitUncheckedError();
assert(next_table_min_key_parsed.sequence < kMaxSequenceNumber);
assert(meta.largest.size() == 0 ||
icmp.Compare(meta.largest.Encode(), next_table_min_key) < 0);
assert(!lower_bound || icmp.Compare(*lower_bound, next_table_min_key) <= 0);
if (meta.largest.size() > 0 &&
ucmp->EqualWithoutTimestamp(meta.largest.user_key(),
next_table_min_key_parsed.user_key)) {
// Caution: this assumes meta.largest.Encode() lives longer than
// upper_bound, which is only true if meta.largest is never updated.
// This just happens to be the case here since meta.largest serves
// as the upper_bound.
upper_bound_guard = meta.largest.Encode();
} else {
SetMaxSeqAndTs(upper_bound_buf, next_table_min_key_parsed.user_key,
ts_sz);
upper_bound_guard = upper_bound_buf.Encode();
}
upper_bound = &upper_bound_guard;
}
if (lower_bound && upper_bound &&
icmp.Compare(*lower_bound, *upper_bound) > 0) {
assert(meta.smallest.size() == 0 &&
ucmp->EqualWithoutTimestamp(ExtractUserKey(*lower_bound),
ExtractUserKey(*upper_bound)));
// This can only happen when lower_bound have the same user key as
// next_table_min_key and that there is no point key in the current
// compaction output file.
return Status::OK();
}
// The end key of the subcompaction must be bigger or equal to the upper
// bound. If the end of subcompaction is null or the upper bound is null,
// it means that this file is the last file in the compaction. So there
// will be no overlapping between this file and others.
assert(comp_end_user_key == nullptr || upper_bound == nullptr ||
ucmp->CompareWithoutTimestamp(ExtractUserKey(*upper_bound),
*comp_end_user_key) <= 0);
auto it = range_del_agg_->NewIterator(lower_bound, upper_bound);
Slice last_tombstone_start_user_key{};
bool reached_lower_bound = false;
const ReadOptions read_options(Env::IOActivity::kCompaction);
for (it->SeekToFirst(); it->Valid(); it->Next()) {
auto tombstone = it->Tombstone();
auto kv = tombstone.Serialize();
InternalKey tombstone_end = tombstone.SerializeEndKey();
// TODO: the underlying iterator should support clamping the bounds.
// tombstone_end.Encode is of form user_key@kMaxSeqno
// if it is equal to lower_bound, there is no need to include
// such range tombstone.
if (!reached_lower_bound && lower_bound &&
icmp.Compare(tombstone_end.Encode(), *lower_bound) <= 0) {
continue;
}
assert(!lower_bound ||
icmp.Compare(*lower_bound, tombstone_end.Encode()) <= 0);
reached_lower_bound = true;
// Garbage collection for range tombstones.
// If user-defined timestamp is enabled, range tombstones are dropped if
// they are at bottommost_level, below full_history_ts_low and not visible
// in any snapshot. trim_ts_ is passed to the constructor for
// range_del_agg_, and range_del_agg_ internally drops tombstones above
// trim_ts_.
bool consider_drop =
tombstone.seq_ <= earliest_snapshot &&
(ts_sz == 0 ||
(!full_history_ts_low.empty() &&
ucmp->CompareTimestamp(tombstone.ts_, full_history_ts_low) < 0));
if (consider_drop && bottommost_level) {
// TODO(andrewkr): tombstones that span multiple output files are
// counted for each compaction output file, so lots of double
// counting.
range_del_out_stats.num_range_del_drop_obsolete++;
range_del_out_stats.num_record_drop_obsolete++;
continue;
}
assert(lower_bound == nullptr ||
ucmp->CompareWithoutTimestamp(ExtractUserKey(*lower_bound),
kv.second) < 0);
InternalKey tombstone_start = kv.first;
if (lower_bound &&
ucmp->CompareWithoutTimestamp(tombstone_start.user_key(),
ExtractUserKey(*lower_bound)) < 0) {
// This just updates the non-timestamp portion of `tombstone_start`'s user
// key. Ideally there would be a simpler API usage
ParsedInternalKey tombstone_start_parsed;
ParseInternalKey(tombstone_start.Encode(), &tombstone_start_parsed,
false /* log_err_key */)
.PermitUncheckedError();
// timestamp should be from where sequence number is from, which is from
// tombstone in this case
std::string ts =
tombstone_start_parsed.GetTimestamp(ucmp->timestamp_size())
.ToString();
tombstone_start_parsed.user_key = ExtractUserKey(*lower_bound);
tombstone_start.SetFrom(tombstone_start_parsed, ts);
}
if (upper_bound != nullptr &&
icmp.Compare(*upper_bound, tombstone_start.Encode()) < 0) {
break;
}
if (lower_bound &&
icmp.Compare(tombstone_start.Encode(), *lower_bound) < 0) {
tombstone_start.DecodeFrom(*lower_bound);
}
if (upper_bound && icmp.Compare(*upper_bound, tombstone_end.Encode()) < 0) {
tombstone_end.DecodeFrom(*upper_bound);
}
if (consider_drop && compaction_->KeyRangeNotExistsBeyondOutputLevel(
tombstone_start.user_key(),
tombstone_end.user_key(), &level_ptrs_)) {
range_del_out_stats.num_range_del_drop_obsolete++;
range_del_out_stats.num_record_drop_obsolete++;
continue;
}
// Here we show that *only* range tombstones that overlap with
// [lower_bound, upper_bound] are added to the current file, and
// sanity checking invariants that should hold:
// - [tombstone_start, tombstone_end] overlaps with [lower_bound,
// upper_bound]
// - meta.smallest <= meta.largest
// Corresponding assertions are made, the proof is broken is any of them
// fails.
// TODO: show that *all* range tombstones that overlap with
// [lower_bound, upper_bound] are added.
// TODO: some invariant about boundaries are correctly updated.
//
// Note that `tombstone_start` is updated in the if condition above, we use
// tombstone_start to refer to its initial value, i.e.,
// it->Tombstone().first, and use tombstone_start* to refer to its value
// after the update.
//
// To show [lower_bound, upper_bound] overlaps with [tombstone_start,
// tombstone_end]:
// lower_bound <= upper_bound from the if condition right after all
// bounds are initialized. We assume each tombstone fragment has
// start_key.user_key < end_key.user_key, so
// tombstone_start < tombstone_end by
// FragmentedTombstoneIterator::Tombstone(). So these two ranges are both
// non-emtpy. The flag `reached_lower_bound` and the if logic before it
// ensures lower_bound <= tombstone_end. tombstone_start is only updated
// if it has a smaller user_key than lower_bound user_key, so
// tombstone_start <= tombstone_start*. The above if condition implies
// tombstone_start* <= upper_bound. So we have
// tombstone_start <= upper_bound and lower_bound <= tombstone_end
// and the two ranges overlap.
//
// To show meta.smallest <= meta.largest:
// From the implementation of UpdateBoundariesForRange(), it suffices to
// prove that when it is first called in this function, its parameters
// satisfy `start <= end`, where start = max(tombstone_start*, lower_bound)
// and end = min(tombstone_end, upper_bound). From the above proof we have
// lower_bound <= tombstone_end and lower_bound <= upper_bound. We only need
// to show that tombstone_start* <= min(tombstone_end, upper_bound).
// Note that tombstone_start*.user_key = max(tombstone_start.user_key,
// lower_bound.user_key). Assuming tombstone_end always has
// kMaxSequenceNumber and lower_bound.seqno < kMaxSequenceNumber.
// Since lower_bound <= tombstone_end and lower_bound.seqno <
// tombstone_end.seqno (in absolute number order, not internal key order),
// lower_bound.user_key < tombstone_end.user_key.
// Since lower_bound.user_key < tombstone_end.user_key and
// tombstone_start.user_key < tombstone_end.user_key, tombstone_start* <
// tombstone_end. Since tombstone_start* <= upper_bound from the above proof
// and tombstone_start* < tombstone_end, tombstone_start* <=
// min(tombstone_end, upper_bound), so the two ranges overlap.
// Range tombstone is not supported by output validator yet.
builder_->Add(kv.first.Encode(), kv.second);
assert(icmp.Compare(tombstone_start, tombstone_end) <= 0);
meta.UpdateBoundariesForRange(tombstone_start, tombstone_end,
tombstone.seq_, icmp);
if (!bottommost_level) {
bool start_user_key_changed =
last_tombstone_start_user_key.empty() ||
ucmp->CompareWithoutTimestamp(last_tombstone_start_user_key,
it->start_key()) < 0;
last_tombstone_start_user_key = it->start_key();
if (start_user_key_changed) {
// If tombstone_start >= tombstone_end, then either no key range is
// covered, or that they have the same user key. If they have the same
// user key, then the internal key range should only be within this
// level, and no keys from older levels is covered.
if (ucmp->CompareWithoutTimestamp(tombstone_start.user_key(),
tombstone_end.user_key()) < 0) {
SizeApproximationOptions approx_opts;
approx_opts.files_size_error_margin = 0.1;
auto approximate_covered_size =
compaction_->input_version()->version_set()->ApproximateSize(
approx_opts, read_options, compaction_->input_version(),
tombstone_start.Encode(), tombstone_end.Encode(),
compaction_->output_level() + 1 /* start_level */,
-1 /* end_level */, kCompaction);
meta.compensated_range_deletion_size += approximate_covered_size;
}
}
}
}
return Status::OK();
}
void CompactionOutputs::FillFilesToCutForTtl() {
if (compaction_->immutable_options()->compaction_style !=
kCompactionStyleLevel ||
compaction_->immutable_options()->compaction_pri !=
kMinOverlappingRatio ||
compaction_->mutable_cf_options()->ttl == 0 ||
compaction_->num_input_levels() < 2 || compaction_->bottommost_level()) {
return;
}
// We define new file with the oldest ancestor time to be younger than 1/4
// TTL, and an old one to be older than 1/2 TTL time.
int64_t temp_current_time;
auto get_time_status =
compaction_->immutable_options()->clock->GetCurrentTime(
&temp_current_time);
if (!get_time_status.ok()) {
return;
}
auto current_time = static_cast<uint64_t>(temp_current_time);
if (current_time < compaction_->mutable_cf_options()->ttl) {
return;
}
uint64_t old_age_thres =
current_time - compaction_->mutable_cf_options()->ttl / 2;
const std::vector<FileMetaData*>& olevel =
*(compaction_->inputs(compaction_->num_input_levels() - 1));
for (FileMetaData* file : olevel) {
// Worth filtering out by start and end?
uint64_t oldest_ancester_time = file->TryGetOldestAncesterTime();
// We put old files if they are not too small to prevent a flood
// of small files.
if (oldest_ancester_time < old_age_thres &&
file->fd.GetFileSize() >
compaction_->mutable_cf_options()->target_file_size_base / 2) {
files_to_cut_for_ttl_.push_back(file);
}
}
}
CompactionOutputs::CompactionOutputs(const Compaction* compaction,
const bool is_penultimate_level)
: compaction_(compaction), is_penultimate_level_(is_penultimate_level) {
partitioner_ = compaction->output_level() == 0
? nullptr
: compaction->CreateSstPartitioner();
if (compaction->output_level() != 0) {
FillFilesToCutForTtl();
}
level_ptrs_ = std::vector<size_t>(compaction_->number_levels(), 0);
}
} // namespace ROCKSDB_NAMESPACE
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