rocksdb/db/builder.cc
Andres Noetzli 014fd55adc Support for SingleDelete()
Summary:
This patch fixes #7460559. It introduces SingleDelete as a new database
operation. This operation can be used to delete keys that were never
overwritten (no put following another put of the same key). If an overwritten
key is single deleted the behavior is undefined. Single deletion of a
non-existent key has no effect but multiple consecutive single deletions are
not allowed (see limitations).

In contrast to the conventional Delete() operation, the deletion entry is
removed along with the value when the two are lined up in a compaction. Note:
The semantics are similar to @igor's prototype that allowed to have this
behavior on the granularity of a column family (
https://reviews.facebook.net/D42093 ). This new patch, however, is more
aggressive when it comes to removing tombstones: It removes the SingleDelete
together with the value whenever there is no snapshot between them while the
older patch only did this when the sequence number of the deletion was older
than the earliest snapshot.

Most of the complex additions are in the Compaction Iterator, all other changes
should be relatively straightforward. The patch also includes basic support for
single deletions in db_stress and db_bench.

Limitations:
- Not compatible with cuckoo hash tables
- Single deletions cannot be used in combination with merges and normal
  deletions on the same key (other keys are not affected by this)
- Consecutive single deletions are currently not allowed (and older version of
  this patch supported this so it could be resurrected if needed)

Test Plan: make all check

Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor

Reviewed By: igor

Subscribers: maykov, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43179
2015-09-17 11:42:56 -07:00

168 lines
5.8 KiB
C++

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same 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/compaction_iterator.h"
#include "db/dbformat.h"
#include "db/filename.h"
#include "db/internal_stats.h"
#include "db/merge_helper.h"
#include "db/table_cache.h"
#include "db/version_edit.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_table_builder.h"
#include "util/file_reader_writer.h"
#include "util/iostats_context_imp.h"
#include "util/stop_watch.h"
#include "util/thread_status_util.h"
namespace rocksdb {
class TableFactory;
TableBuilder* NewTableBuilder(
const ImmutableCFOptions& ioptions,
const InternalKeyComparator& internal_comparator,
const std::vector<std::unique_ptr<IntTblPropCollectorFactory>>*
int_tbl_prop_collector_factories,
WritableFileWriter* file, const CompressionType compression_type,
const CompressionOptions& compression_opts, const bool skip_filters) {
return ioptions.table_factory->NewTableBuilder(
TableBuilderOptions(ioptions, internal_comparator,
int_tbl_prop_collector_factories, compression_type,
compression_opts, skip_filters),
file);
}
Status BuildTable(
const std::string& dbname, Env* env, const ImmutableCFOptions& ioptions,
const EnvOptions& env_options, TableCache* table_cache, Iterator* iter,
FileMetaData* meta, const InternalKeyComparator& internal_comparator,
const std::vector<std::unique_ptr<IntTblPropCollectorFactory>>*
int_tbl_prop_collector_factories,
std::vector<SequenceNumber> snapshots, const CompressionType compression,
const CompressionOptions& compression_opts, bool paranoid_file_checks,
InternalStats* internal_stats, const Env::IOPriority io_priority,
TableProperties* table_properties) {
// Reports the IOStats for flush for every following bytes.
const size_t kReportFlushIOStatsEvery = 1048576;
Status s;
meta->fd.file_size = 0;
iter->SeekToFirst();
std::string fname = TableFileName(ioptions.db_paths, meta->fd.GetNumber(),
meta->fd.GetPathId());
if (iter->Valid()) {
TableBuilder* builder;
unique_ptr<WritableFileWriter> file_writer;
{
unique_ptr<WritableFile> file;
s = env->NewWritableFile(fname, &file, env_options);
if (!s.ok()) {
return s;
}
file->SetIOPriority(io_priority);
file_writer.reset(new WritableFileWriter(std::move(file), env_options));
builder = NewTableBuilder(
ioptions, internal_comparator, int_tbl_prop_collector_factories,
file_writer.get(), compression, compression_opts);
}
MergeHelper merge(internal_comparator.user_comparator(),
ioptions.merge_operator, ioptions.info_log,
ioptions.min_partial_merge_operands,
true /* internal key corruption is not ok */);
CompactionIterator c_iter(iter, internal_comparator.user_comparator(),
&merge, kMaxSequenceNumber, &snapshots, env,
true /* internal key corruption is not ok */);
c_iter.SeekToFirst();
for (; c_iter.Valid(); c_iter.Next()) {
const Slice& key = c_iter.key();
const Slice& value = c_iter.value();
builder->Add(key, value);
meta->UpdateBoundaries(key, c_iter.ikey().sequence);
// TODO(noetzli): Update stats after flush, too.
if (io_priority == Env::IO_HIGH &&
IOSTATS(bytes_written) >= kReportFlushIOStatsEvery) {
ThreadStatusUtil::IncreaseThreadOperationProperty(
ThreadStatus::FLUSH_BYTES_WRITTEN, IOSTATS(bytes_written));
IOSTATS_RESET(bytes_written);
}
}
// Finish and check for builder errors
bool empty = builder->NumEntries() == 0;
s = c_iter.status();
if (!s.ok() || empty) {
builder->Abandon();
} else {
s = builder->Finish();
}
if (s.ok() && !empty) {
meta->fd.file_size = builder->FileSize();
meta->marked_for_compaction = builder->NeedCompact();
assert(meta->fd.GetFileSize() > 0);
if (table_properties) {
*table_properties = builder->GetTableProperties();
}
}
delete builder;
// Finish and check for file errors
if (s.ok() && !empty && !ioptions.disable_data_sync) {
StopWatch sw(env, ioptions.statistics, TABLE_SYNC_MICROS);
file_writer->Sync(ioptions.use_fsync);
}
if (s.ok() && !empty) {
s = file_writer->Close();
}
if (s.ok() && !empty) {
// Verify that the table is usable
std::unique_ptr<Iterator> it(table_cache->NewIterator(
ReadOptions(), env_options, internal_comparator, meta->fd, nullptr,
(internal_stats == nullptr) ? nullptr
: internal_stats->GetFileReadHist(0),
false));
s = it->status();
if (s.ok() && paranoid_file_checks) {
for (it->SeekToFirst(); it->Valid(); it->Next()) {
}
s = it->status();
}
}
}
// Check for input iterator errors
if (!iter->status().ok()) {
s = iter->status();
}
if (!s.ok() || meta->fd.GetFileSize() == 0) {
env->DeleteFile(fname);
}
return s;
}
} // namespace rocksdb