rocksdb/db/builder.cc
Hui Xiao 8f763bdeab Record and use the tail size to prefetch table tail (#11406)
Summary:
**Context:**
We prefetch the tail part of a SST file (i.e, the blocks after data blocks till the end of the file) during each SST file open in hope to prefetch all the stuff at once ahead of time for later read e.g, footer, meta index, filter/index etc. The existing approach to estimate the tail size to prefetch is through `TailPrefetchStats` heuristics introduced in https://github.com/facebook/rocksdb/pull/4156, which has caused small reads in unlucky case (e.g,  small read into the tail buffer during table open in thread 1 under the same BlockBasedTableFactory object can make thread 2's tail prefetching use a small size that it shouldn't) and is hard to debug.  Therefore we decide to record the exact tail size and use it directly  to prefetch tail of the SST instead of relying heuristics.

**Summary:**
- Obtain and record in manifest the tail size in `BlockBasedTableBuilder::Finish()`
   - For backward compatibility, we fall back to TailPrefetchStats and last to simple heuristics that the tail size is a linear portion of the file size - see PR conversation for more.
- Make`tail_start_offset` part of the table properties and deduct tail size to record in manifest for external files (e.g, file ingestion, import CF) and db repair (with no access to manifest).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11406

Test Plan:
1. New UT
2. db bench
Note: db bench on /tmp/ where direct read is supported is too slow to finish and the default pinning setting in db bench is not helpful to profile # sst read of Get. Therefore I hacked the following to obtain the following comparison.
```
 diff --git a/table/block_based/block_based_table_reader.cc b/table/block_based/block_based_table_reader.cc
index bd5669f0f..791484c1f 100644
 --- a/table/block_based/block_based_table_reader.cc
+++ b/table/block_based/block_based_table_reader.cc
@@ -838,7 +838,7 @@ Status BlockBasedTable::PrefetchTail(
                            &tail_prefetch_size);

   // Try file system prefetch
-  if (!file->use_direct_io() && !force_direct_prefetch) {
+  if (false && !file->use_direct_io() && !force_direct_prefetch) {
     if (!file->Prefetch(prefetch_off, prefetch_len, ro.rate_limiter_priority)
              .IsNotSupported()) {
       prefetch_buffer->reset(new FilePrefetchBuffer(
 diff --git a/tools/db_bench_tool.cc b/tools/db_bench_tool.cc
index ea40f5fa0..39a0ac385 100644
 --- a/tools/db_bench_tool.cc
+++ b/tools/db_bench_tool.cc
@@ -4191,6 +4191,8 @@ class Benchmark {
           std::shared_ptr<TableFactory>(NewCuckooTableFactory(table_options));
     } else {
       BlockBasedTableOptions block_based_options;
+      block_based_options.metadata_cache_options.partition_pinning =
+      PinningTier::kAll;
       block_based_options.checksum =
           static_cast<ChecksumType>(FLAGS_checksum_type);
       if (FLAGS_use_hash_search) {
```
Create DB
```
./db_bench --bloom_bits=3 --use_existing_db=1 --seed=1682546046158958 --partition_index_and_filters=1 --statistics=1 -db=/dev/shm/testdb/ -benchmarks=readrandom -key_size=3200 -value_size=512 -num=1000000 -write_buffer_size=6550000 -disable_auto_compactions=false -target_file_size_base=6550000 -compression_type=none
```
ReadRandom
```
./db_bench --bloom_bits=3 --use_existing_db=1 --seed=1682546046158958 --partition_index_and_filters=1 --statistics=1 -db=/dev/shm/testdb/ -benchmarks=readrandom -key_size=3200 -value_size=512 -num=1000000 -write_buffer_size=6550000 -disable_auto_compactions=false -target_file_size_base=6550000 -compression_type=none
```
(a) Existing (Use TailPrefetchStats for tail size + use seperate prefetch buffer in PartitionedFilter/IndexReader::CacheDependencies())
```
rocksdb.table.open.prefetch.tail.hit COUNT : 3395
rocksdb.sst.read.micros P50 : 5.655570 P95 : 9.931396 P99 : 14.845454 P100 : 585.000000 COUNT : 999905 SUM : 6590614
```

(b) This PR (Record tail size + use the same tail buffer in PartitionedFilter/IndexReader::CacheDependencies())
```
rocksdb.table.open.prefetch.tail.hit COUNT : 14257
rocksdb.sst.read.micros P50 : 5.173347 P95 : 9.015017 P99 : 12.912610 P100 : 228.000000 COUNT : 998547 SUM : 5976540
```

As we can see, we increase the prefetch tail hit count and decrease SST read count with this PR

3. Test backward compatibility by stepping through reading with post-PR code on a db generated pre-PR.

Reviewed By: pdillinger

Differential Revision: D45413346

Pulled By: hx235

fbshipit-source-id: 7d5e36a60a72477218f79905168d688452a4c064
2023-05-08 13:14:28 -07:00

448 lines
18 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// 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/builder.h"
#include <algorithm>
#include <deque>
#include <vector>
#include "db/blob/blob_file_builder.h"
#include "db/compaction/compaction_iterator.h"
#include "db/event_helpers.h"
#include "db/internal_stats.h"
#include "db/merge_helper.h"
#include "db/output_validator.h"
#include "db/range_del_aggregator.h"
#include "db/table_cache.h"
#include "db/version_edit.h"
#include "file/file_util.h"
#include "file/filename.h"
#include "file/read_write_util.h"
#include "file/writable_file_writer.h"
#include "monitoring/iostats_context_imp.h"
#include "monitoring/thread_status_util.h"
#include "options/options_helper.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "rocksdb/options.h"
#include "rocksdb/table.h"
#include "table/block_based/block_based_table_builder.h"
#include "table/format.h"
#include "table/internal_iterator.h"
#include "table/unique_id_impl.h"
#include "test_util/sync_point.h"
#include "util/stop_watch.h"
namespace ROCKSDB_NAMESPACE {
class TableFactory;
TableBuilder* NewTableBuilder(const TableBuilderOptions& tboptions,
WritableFileWriter* file) {
assert((tboptions.column_family_id ==
TablePropertiesCollectorFactory::Context::kUnknownColumnFamily) ==
tboptions.column_family_name.empty());
return tboptions.ioptions.table_factory->NewTableBuilder(tboptions, file);
}
Status BuildTable(
const std::string& dbname, VersionSet* versions,
const ImmutableDBOptions& db_options, const TableBuilderOptions& tboptions,
const FileOptions& file_options, const ReadOptions& read_options,
TableCache* table_cache, InternalIterator* iter,
std::vector<std::unique_ptr<FragmentedRangeTombstoneIterator>>
range_del_iters,
FileMetaData* meta, std::vector<BlobFileAddition>* blob_file_additions,
std::vector<SequenceNumber> snapshots,
SequenceNumber earliest_write_conflict_snapshot,
SequenceNumber job_snapshot, SnapshotChecker* snapshot_checker,
bool paranoid_file_checks, InternalStats* internal_stats,
IOStatus* io_status, const std::shared_ptr<IOTracer>& io_tracer,
BlobFileCreationReason blob_creation_reason,
const SeqnoToTimeMapping& seqno_to_time_mapping, EventLogger* event_logger,
int job_id, const Env::IOPriority io_priority,
TableProperties* table_properties, Env::WriteLifeTimeHint write_hint,
const std::string* full_history_ts_low,
BlobFileCompletionCallback* blob_callback, Version* version,
uint64_t* num_input_entries, uint64_t* memtable_payload_bytes,
uint64_t* memtable_garbage_bytes) {
assert((tboptions.column_family_id ==
TablePropertiesCollectorFactory::Context::kUnknownColumnFamily) ==
tboptions.column_family_name.empty());
auto& mutable_cf_options = tboptions.moptions;
auto& ioptions = tboptions.ioptions;
// Reports the IOStats for flush for every following bytes.
const size_t kReportFlushIOStatsEvery = 1048576;
OutputValidator output_validator(
tboptions.internal_comparator,
/*enable_order_check=*/
mutable_cf_options.check_flush_compaction_key_order,
/*enable_hash=*/paranoid_file_checks);
Status s;
meta->fd.file_size = 0;
iter->SeekToFirst();
std::unique_ptr<CompactionRangeDelAggregator> range_del_agg(
new CompactionRangeDelAggregator(&tboptions.internal_comparator,
snapshots, full_history_ts_low));
uint64_t num_unfragmented_tombstones = 0;
uint64_t total_tombstone_payload_bytes = 0;
for (auto& range_del_iter : range_del_iters) {
num_unfragmented_tombstones +=
range_del_iter->num_unfragmented_tombstones();
total_tombstone_payload_bytes +=
range_del_iter->total_tombstone_payload_bytes();
range_del_agg->AddTombstones(std::move(range_del_iter));
}
std::string fname = TableFileName(ioptions.cf_paths, meta->fd.GetNumber(),
meta->fd.GetPathId());
std::vector<std::string> blob_file_paths;
std::string file_checksum = kUnknownFileChecksum;
std::string file_checksum_func_name = kUnknownFileChecksumFuncName;
EventHelpers::NotifyTableFileCreationStarted(ioptions.listeners, dbname,
tboptions.column_family_name,
fname, job_id, tboptions.reason);
Env* env = db_options.env;
assert(env);
FileSystem* fs = db_options.fs.get();
assert(fs);
TableProperties tp;
bool table_file_created = false;
if (iter->Valid() || !range_del_agg->IsEmpty()) {
std::unique_ptr<CompactionFilter> compaction_filter;
if (ioptions.compaction_filter_factory != nullptr &&
ioptions.compaction_filter_factory->ShouldFilterTableFileCreation(
tboptions.reason)) {
CompactionFilter::Context context;
context.is_full_compaction = false;
context.is_manual_compaction = false;
context.column_family_id = tboptions.column_family_id;
context.reason = tboptions.reason;
compaction_filter =
ioptions.compaction_filter_factory->CreateCompactionFilter(context);
if (compaction_filter != nullptr &&
!compaction_filter->IgnoreSnapshots()) {
s.PermitUncheckedError();
return Status::NotSupported(
"CompactionFilter::IgnoreSnapshots() = false is not supported "
"anymore.");
}
}
TableBuilder* builder;
std::unique_ptr<WritableFileWriter> file_writer;
{
std::unique_ptr<FSWritableFile> file;
#ifndef NDEBUG
bool use_direct_writes = file_options.use_direct_writes;
TEST_SYNC_POINT_CALLBACK("BuildTable:create_file", &use_direct_writes);
#endif // !NDEBUG
IOStatus io_s = NewWritableFile(fs, fname, &file, file_options);
assert(s.ok());
s = io_s;
if (io_status->ok()) {
*io_status = io_s;
}
if (!s.ok()) {
EventHelpers::LogAndNotifyTableFileCreationFinished(
event_logger, ioptions.listeners, dbname,
tboptions.column_family_name, fname, job_id, meta->fd,
kInvalidBlobFileNumber, tp, tboptions.reason, s, file_checksum,
file_checksum_func_name);
return s;
}
table_file_created = true;
FileTypeSet tmp_set = ioptions.checksum_handoff_file_types;
file->SetIOPriority(io_priority);
file->SetWriteLifeTimeHint(write_hint);
file_writer.reset(new WritableFileWriter(
std::move(file), fname, file_options, ioptions.clock, io_tracer,
ioptions.stats, ioptions.listeners,
ioptions.file_checksum_gen_factory.get(),
tmp_set.Contains(FileType::kTableFile), false));
builder = NewTableBuilder(tboptions, file_writer.get());
}
auto ucmp = tboptions.internal_comparator.user_comparator();
MergeHelper merge(
env, ucmp, ioptions.merge_operator.get(), compaction_filter.get(),
ioptions.logger, true /* internal key corruption is not ok */,
snapshots.empty() ? 0 : snapshots.back(), snapshot_checker);
std::unique_ptr<BlobFileBuilder> blob_file_builder(
(mutable_cf_options.enable_blob_files &&
tboptions.level_at_creation >=
mutable_cf_options.blob_file_starting_level &&
blob_file_additions)
? new BlobFileBuilder(
versions, fs, &ioptions, &mutable_cf_options, &file_options,
tboptions.db_id, tboptions.db_session_id, job_id,
tboptions.column_family_id, tboptions.column_family_name,
io_priority, write_hint, io_tracer, blob_callback,
blob_creation_reason, &blob_file_paths, blob_file_additions)
: nullptr);
const std::atomic<bool> kManualCompactionCanceledFalse{false};
CompactionIterator c_iter(
iter, ucmp, &merge, kMaxSequenceNumber, &snapshots,
earliest_write_conflict_snapshot, job_snapshot, snapshot_checker, env,
ShouldReportDetailedTime(env, ioptions.stats),
true /* internal key corruption is not ok */, range_del_agg.get(),
blob_file_builder.get(), ioptions.allow_data_in_errors,
ioptions.enforce_single_del_contracts,
/*manual_compaction_canceled=*/kManualCompactionCanceledFalse,
/*compaction=*/nullptr, compaction_filter.get(),
/*shutting_down=*/nullptr, db_options.info_log, full_history_ts_low);
c_iter.SeekToFirst();
for (; c_iter.Valid(); c_iter.Next()) {
const Slice& key = c_iter.key();
const Slice& value = c_iter.value();
const ParsedInternalKey& ikey = c_iter.ikey();
// Generate a rolling 64-bit hash of the key and values
// Note :
// Here "key" integrates 'sequence_number'+'kType'+'user key'.
s = output_validator.Add(key, value);
if (!s.ok()) {
break;
}
builder->Add(key, value);
s = meta->UpdateBoundaries(key, value, ikey.sequence, ikey.type);
if (!s.ok()) {
break;
}
// TODO(noetzli): Update stats after flush, too.
if (io_priority == Env::IO_HIGH &&
IOSTATS(bytes_written) >= kReportFlushIOStatsEvery) {
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::FLUSH_BYTES_WRITTEN, IOSTATS(bytes_written));
}
}
if (!s.ok()) {
c_iter.status().PermitUncheckedError();
} else if (!c_iter.status().ok()) {
s = c_iter.status();
}
if (s.ok()) {
auto range_del_it = range_del_agg->NewIterator();
Slice last_tombstone_start_user_key{};
for (range_del_it->SeekToFirst(); range_del_it->Valid();
range_del_it->Next()) {
auto tombstone = range_del_it->Tombstone();
auto kv = tombstone.Serialize();
builder->Add(kv.first.Encode(), kv.second);
InternalKey tombstone_end = tombstone.SerializeEndKey();
meta->UpdateBoundariesForRange(kv.first, tombstone_end, tombstone.seq_,
tboptions.internal_comparator);
if (version) {
if (last_tombstone_start_user_key.empty() ||
ucmp->CompareWithoutTimestamp(last_tombstone_start_user_key,
range_del_it->start_key()) < 0) {
SizeApproximationOptions approx_opts;
approx_opts.files_size_error_margin = 0.1;
meta->compensated_range_deletion_size += versions->ApproximateSize(
approx_opts, read_options, version, kv.first.Encode(),
tombstone_end.Encode(), 0 /* start_level */, -1 /* end_level */,
TableReaderCaller::kFlush);
}
last_tombstone_start_user_key = range_del_it->start_key();
}
}
}
TEST_SYNC_POINT("BuildTable:BeforeFinishBuildTable");
const bool empty = builder->IsEmpty();
if (num_input_entries != nullptr) {
*num_input_entries =
c_iter.num_input_entry_scanned() + num_unfragmented_tombstones;
}
if (!s.ok() || empty) {
builder->Abandon();
} else {
std::string seqno_time_mapping_str;
seqno_to_time_mapping.Encode(
seqno_time_mapping_str, meta->fd.smallest_seqno,
meta->fd.largest_seqno, meta->file_creation_time);
builder->SetSeqnoTimeTableProperties(
seqno_time_mapping_str,
ioptions.compaction_style == CompactionStyle::kCompactionStyleFIFO
? meta->file_creation_time
: meta->oldest_ancester_time);
s = builder->Finish();
}
if (io_status->ok()) {
*io_status = builder->io_status();
}
if (s.ok() && !empty) {
uint64_t file_size = builder->FileSize();
meta->fd.file_size = file_size;
meta->tail_size = builder->GetTailSize();
meta->marked_for_compaction = builder->NeedCompact();
assert(meta->fd.GetFileSize() > 0);
tp = builder
->GetTableProperties(); // refresh now that builder is finished
if (memtable_payload_bytes != nullptr &&
memtable_garbage_bytes != nullptr) {
const CompactionIterationStats& ci_stats = c_iter.iter_stats();
uint64_t total_payload_bytes = ci_stats.total_input_raw_key_bytes +
ci_stats.total_input_raw_value_bytes +
total_tombstone_payload_bytes;
uint64_t total_payload_bytes_written =
(tp.raw_key_size + tp.raw_value_size);
// Prevent underflow, which may still happen at this point
// since we only support inserts, deletes, and deleteRanges.
if (total_payload_bytes_written <= total_payload_bytes) {
*memtable_payload_bytes = total_payload_bytes;
*memtable_garbage_bytes =
total_payload_bytes - total_payload_bytes_written;
} else {
*memtable_payload_bytes = 0;
*memtable_garbage_bytes = 0;
}
}
if (table_properties) {
*table_properties = tp;
}
}
delete builder;
// Finish and check for file errors
TEST_SYNC_POINT("BuildTable:BeforeSyncTable");
if (s.ok() && !empty) {
StopWatch sw(ioptions.clock, ioptions.stats, TABLE_SYNC_MICROS);
*io_status = file_writer->Sync(ioptions.use_fsync);
}
TEST_SYNC_POINT("BuildTable:BeforeCloseTableFile");
if (s.ok() && io_status->ok() && !empty) {
*io_status = file_writer->Close();
}
if (s.ok() && io_status->ok() && !empty) {
// Add the checksum information to file metadata.
meta->file_checksum = file_writer->GetFileChecksum();
meta->file_checksum_func_name = file_writer->GetFileChecksumFuncName();
file_checksum = meta->file_checksum;
file_checksum_func_name = meta->file_checksum_func_name;
// Set unique_id only if db_id and db_session_id exist
if (!tboptions.db_id.empty() && !tboptions.db_session_id.empty()) {
if (!GetSstInternalUniqueId(tboptions.db_id, tboptions.db_session_id,
meta->fd.GetNumber(), &(meta->unique_id))
.ok()) {
// if failed to get unique id, just set it Null
meta->unique_id = kNullUniqueId64x2;
}
}
}
if (s.ok()) {
s = *io_status;
}
if (blob_file_builder) {
if (s.ok()) {
s = blob_file_builder->Finish();
} else {
blob_file_builder->Abandon(s);
}
blob_file_builder.reset();
}
// TODO Also check the IO status when create the Iterator.
TEST_SYNC_POINT("BuildTable:BeforeOutputValidation");
if (s.ok() && !empty) {
// Verify that the table is usable
// We set for_compaction to false and don't OptimizeForCompactionTableRead
// here because this is a special case after we finish the table building.
// No matter whether use_direct_io_for_flush_and_compaction is true,
// the goal is to cache it here for further user reads.
std::unique_ptr<InternalIterator> it(table_cache->NewIterator(
read_options, file_options, tboptions.internal_comparator, *meta,
nullptr /* range_del_agg */, mutable_cf_options.prefix_extractor,
nullptr,
(internal_stats == nullptr) ? nullptr
: internal_stats->GetFileReadHist(0),
TableReaderCaller::kFlush, /*arena=*/nullptr,
/*skip_filter=*/false, tboptions.level_at_creation,
MaxFileSizeForL0MetaPin(mutable_cf_options),
/*smallest_compaction_key=*/nullptr,
/*largest_compaction_key*/ nullptr,
/*allow_unprepared_value*/ false,
mutable_cf_options.block_protection_bytes_per_key));
s = it->status();
if (s.ok() && paranoid_file_checks) {
OutputValidator file_validator(tboptions.internal_comparator,
/*enable_order_check=*/true,
/*enable_hash=*/true);
for (it->SeekToFirst(); it->Valid(); it->Next()) {
// Generate a rolling 64-bit hash of the key and values
file_validator.Add(it->key(), it->value()).PermitUncheckedError();
}
s = it->status();
if (s.ok() && !output_validator.CompareValidator(file_validator)) {
s = Status::Corruption("Paranoid checksums do not match");
}
}
}
}
// Check for input iterator errors
if (!iter->status().ok()) {
s = iter->status();
}
if (!s.ok() || meta->fd.GetFileSize() == 0) {
TEST_SYNC_POINT("BuildTable:BeforeDeleteFile");
constexpr IODebugContext* dbg = nullptr;
if (table_file_created) {
Status ignored = fs->DeleteFile(fname, IOOptions(), dbg);
ignored.PermitUncheckedError();
}
assert(blob_file_additions || blob_file_paths.empty());
if (blob_file_additions) {
for (const std::string& blob_file_path : blob_file_paths) {
Status ignored = DeleteDBFile(&db_options, blob_file_path, dbname,
/*force_bg=*/false, /*force_fg=*/false);
ignored.PermitUncheckedError();
TEST_SYNC_POINT("BuildTable::AfterDeleteFile");
}
}
}
Status status_for_listener = s;
if (meta->fd.GetFileSize() == 0) {
fname = "(nil)";
if (s.ok()) {
status_for_listener = Status::Aborted("Empty SST file not kept");
}
}
// Output to event logger and fire events.
EventHelpers::LogAndNotifyTableFileCreationFinished(
event_logger, ioptions.listeners, dbname, tboptions.column_family_name,
fname, job_id, meta->fd, meta->oldest_blob_file_number, tp,
tboptions.reason, status_for_listener, file_checksum,
file_checksum_func_name);
return s;
}
} // namespace ROCKSDB_NAMESPACE