Revision b07369836eb41ec831a060907ea00a9a15de6fe3 authored by Yi Wu on 02 May 2017, 04:49:09 UTC, committed by Yi Wu on 02 May 2017, 04:49:09 UTC
1 parent f3dc93b
statistics.h
// Copyright (c) 2011-present, 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.
#ifndef STORAGE_ROCKSDB_INCLUDE_STATISTICS_H_
#define STORAGE_ROCKSDB_INCLUDE_STATISTICS_H_
#include <atomic>
#include <cstddef>
#include <cstdint>
#include <string>
#include <memory>
#include <vector>
namespace rocksdb {
/**
* Keep adding ticker's here.
* 1. Any ticker should be added before TICKER_ENUM_MAX.
* 2. Add a readable string in TickersNameMap below for the newly added ticker.
*/
enum Tickers : uint32_t {
// total block cache misses
// REQUIRES: BLOCK_CACHE_MISS == BLOCK_CACHE_INDEX_MISS +
// BLOCK_CACHE_FILTER_MISS +
// BLOCK_CACHE_DATA_MISS;
BLOCK_CACHE_MISS = 0,
// total block cache hit
// REQUIRES: BLOCK_CACHE_HIT == BLOCK_CACHE_INDEX_HIT +
// BLOCK_CACHE_FILTER_HIT +
// BLOCK_CACHE_DATA_HIT;
BLOCK_CACHE_HIT,
// # of blocks added to block cache.
BLOCK_CACHE_ADD,
// # of failures when adding blocks to block cache.
BLOCK_CACHE_ADD_FAILURES,
// # of times cache miss when accessing index block from block cache.
BLOCK_CACHE_INDEX_MISS,
// # of times cache hit when accessing index block from block cache.
BLOCK_CACHE_INDEX_HIT,
// # of index blocks added to block cache.
BLOCK_CACHE_INDEX_ADD,
// # of bytes of index blocks inserted into cache
BLOCK_CACHE_INDEX_BYTES_INSERT,
// # of bytes of index block erased from cache
BLOCK_CACHE_INDEX_BYTES_EVICT,
// # of times cache miss when accessing filter block from block cache.
BLOCK_CACHE_FILTER_MISS,
// # of times cache hit when accessing filter block from block cache.
BLOCK_CACHE_FILTER_HIT,
// # of filter blocks added to block cache.
BLOCK_CACHE_FILTER_ADD,
// # of bytes of bloom filter blocks inserted into cache
BLOCK_CACHE_FILTER_BYTES_INSERT,
// # of bytes of bloom filter block erased from cache
BLOCK_CACHE_FILTER_BYTES_EVICT,
// # of times cache miss when accessing data block from block cache.
BLOCK_CACHE_DATA_MISS,
// # of times cache hit when accessing data block from block cache.
BLOCK_CACHE_DATA_HIT,
// # of data blocks added to block cache.
BLOCK_CACHE_DATA_ADD,
// # of bytes of data blocks inserted into cache
BLOCK_CACHE_DATA_BYTES_INSERT,
// # of bytes read from cache.
BLOCK_CACHE_BYTES_READ,
// # of bytes written into cache.
BLOCK_CACHE_BYTES_WRITE,
// # of times bloom filter has avoided file reads.
BLOOM_FILTER_USEFUL,
// # persistent cache hit
PERSISTENT_CACHE_HIT,
// # persistent cache miss
PERSISTENT_CACHE_MISS,
// # total simulation block cache hits
SIM_BLOCK_CACHE_HIT,
// # total simulation block cache misses
SIM_BLOCK_CACHE_MISS,
// # of memtable hits.
MEMTABLE_HIT,
// # of memtable misses.
MEMTABLE_MISS,
// # of Get() queries served by L0
GET_HIT_L0,
// # of Get() queries served by L1
GET_HIT_L1,
// # of Get() queries served by L2 and up
GET_HIT_L2_AND_UP,
/**
* COMPACTION_KEY_DROP_* count the reasons for key drop during compaction
* There are 4 reasons currently.
*/
COMPACTION_KEY_DROP_NEWER_ENTRY, // key was written with a newer value.
// Also includes keys dropped for range del.
COMPACTION_KEY_DROP_OBSOLETE, // The key is obsolete.
COMPACTION_KEY_DROP_RANGE_DEL, // key was covered by a range tombstone.
COMPACTION_KEY_DROP_USER, // user compaction function has dropped the key.
COMPACTION_RANGE_DEL_DROP_OBSOLETE, // all keys in range were deleted.
// Number of keys written to the database via the Put and Write call's
NUMBER_KEYS_WRITTEN,
// Number of Keys read,
NUMBER_KEYS_READ,
// Number keys updated, if inplace update is enabled
NUMBER_KEYS_UPDATED,
// The number of uncompressed bytes issued by DB::Put(), DB::Delete(),
// DB::Merge(), and DB::Write().
BYTES_WRITTEN,
// The number of uncompressed bytes read from DB::Get(). It could be
// either from memtables, cache, or table files.
// For the number of logical bytes read from DB::MultiGet(),
// please use NUMBER_MULTIGET_BYTES_READ.
BYTES_READ,
// The number of calls to seek/next/prev
NUMBER_DB_SEEK,
NUMBER_DB_NEXT,
NUMBER_DB_PREV,
// The number of calls to seek/next/prev that returned data
NUMBER_DB_SEEK_FOUND,
NUMBER_DB_NEXT_FOUND,
NUMBER_DB_PREV_FOUND,
// The number of uncompressed bytes read from an iterator.
// Includes size of key and value.
ITER_BYTES_READ,
NO_FILE_CLOSES,
NO_FILE_OPENS,
NO_FILE_ERRORS,
// DEPRECATED Time system had to wait to do LO-L1 compactions
STALL_L0_SLOWDOWN_MICROS,
// DEPRECATED Time system had to wait to move memtable to L1.
STALL_MEMTABLE_COMPACTION_MICROS,
// DEPRECATED write throttle because of too many files in L0
STALL_L0_NUM_FILES_MICROS,
// Writer has to wait for compaction or flush to finish.
STALL_MICROS,
// The wait time for db mutex.
// Disabled by default. To enable it set stats level to kAll
DB_MUTEX_WAIT_MICROS,
RATE_LIMIT_DELAY_MILLIS,
NO_ITERATORS, // number of iterators currently open
// Number of MultiGet calls, keys read, and bytes read
NUMBER_MULTIGET_CALLS,
NUMBER_MULTIGET_KEYS_READ,
NUMBER_MULTIGET_BYTES_READ,
// Number of deletes records that were not required to be
// written to storage because key does not exist
NUMBER_FILTERED_DELETES,
NUMBER_MERGE_FAILURES,
// number of times bloom was checked before creating iterator on a
// file, and the number of times the check was useful in avoiding
// iterator creation (and thus likely IOPs).
BLOOM_FILTER_PREFIX_CHECKED,
BLOOM_FILTER_PREFIX_USEFUL,
// Number of times we had to reseek inside an iteration to skip
// over large number of keys with same userkey.
NUMBER_OF_RESEEKS_IN_ITERATION,
// Record the number of calls to GetUpadtesSince. Useful to keep track of
// transaction log iterator refreshes
GET_UPDATES_SINCE_CALLS,
BLOCK_CACHE_COMPRESSED_MISS, // miss in the compressed block cache
BLOCK_CACHE_COMPRESSED_HIT, // hit in the compressed block cache
// Number of blocks added to comopressed block cache
BLOCK_CACHE_COMPRESSED_ADD,
// Number of failures when adding blocks to compressed block cache
BLOCK_CACHE_COMPRESSED_ADD_FAILURES,
WAL_FILE_SYNCED, // Number of times WAL sync is done
WAL_FILE_BYTES, // Number of bytes written to WAL
// Writes can be processed by requesting thread or by the thread at the
// head of the writers queue.
WRITE_DONE_BY_SELF,
WRITE_DONE_BY_OTHER, // Equivalent to writes done for others
WRITE_TIMEDOUT, // Number of writes ending up with timed-out.
WRITE_WITH_WAL, // Number of Write calls that request WAL
COMPACT_READ_BYTES, // Bytes read during compaction
COMPACT_WRITE_BYTES, // Bytes written during compaction
FLUSH_WRITE_BYTES, // Bytes written during flush
// Number of table's properties loaded directly from file, without creating
// table reader object.
NUMBER_DIRECT_LOAD_TABLE_PROPERTIES,
NUMBER_SUPERVERSION_ACQUIRES,
NUMBER_SUPERVERSION_RELEASES,
NUMBER_SUPERVERSION_CLEANUPS,
// # of compressions/decompressions executed
NUMBER_BLOCK_COMPRESSED,
NUMBER_BLOCK_DECOMPRESSED,
NUMBER_BLOCK_NOT_COMPRESSED,
MERGE_OPERATION_TOTAL_TIME,
FILTER_OPERATION_TOTAL_TIME,
// Row cache.
ROW_CACHE_HIT,
ROW_CACHE_MISS,
// Read amplification statistics.
// Read amplification can be calculated using this formula
// (READ_AMP_TOTAL_READ_BYTES / READ_AMP_ESTIMATE_USEFUL_BYTES)
//
// REQUIRES: ReadOptions::read_amp_bytes_per_bit to be enabled
READ_AMP_ESTIMATE_USEFUL_BYTES, // Estimate of total bytes actually used.
READ_AMP_TOTAL_READ_BYTES, // Total size of loaded data blocks.
// Number of refill intervals where rate limiter's bytes are fully consumed.
NUMBER_RATE_LIMITER_DRAINS,
TICKER_ENUM_MAX
};
// The order of items listed in Tickers should be the same as
// the order listed in TickersNameMap
const std::vector<std::pair<Tickers, std::string>> TickersNameMap = {
{BLOCK_CACHE_MISS, "rocksdb.block.cache.miss"},
{BLOCK_CACHE_HIT, "rocksdb.block.cache.hit"},
{BLOCK_CACHE_ADD, "rocksdb.block.cache.add"},
{BLOCK_CACHE_ADD_FAILURES, "rocksdb.block.cache.add.failures"},
{BLOCK_CACHE_INDEX_MISS, "rocksdb.block.cache.index.miss"},
{BLOCK_CACHE_INDEX_HIT, "rocksdb.block.cache.index.hit"},
{BLOCK_CACHE_INDEX_ADD, "rocksdb.block.cache.index.add"},
{BLOCK_CACHE_INDEX_BYTES_INSERT, "rocksdb.block.cache.index.bytes.insert"},
{BLOCK_CACHE_INDEX_BYTES_EVICT, "rocksdb.block.cache.index.bytes.evict"},
{BLOCK_CACHE_FILTER_MISS, "rocksdb.block.cache.filter.miss"},
{BLOCK_CACHE_FILTER_HIT, "rocksdb.block.cache.filter.hit"},
{BLOCK_CACHE_FILTER_ADD, "rocksdb.block.cache.filter.add"},
{BLOCK_CACHE_FILTER_BYTES_INSERT,
"rocksdb.block.cache.filter.bytes.insert"},
{BLOCK_CACHE_FILTER_BYTES_EVICT, "rocksdb.block.cache.filter.bytes.evict"},
{BLOCK_CACHE_DATA_MISS, "rocksdb.block.cache.data.miss"},
{BLOCK_CACHE_DATA_HIT, "rocksdb.block.cache.data.hit"},
{BLOCK_CACHE_DATA_ADD, "rocksdb.block.cache.data.add"},
{BLOCK_CACHE_DATA_BYTES_INSERT, "rocksdb.block.cache.data.bytes.insert"},
{BLOCK_CACHE_BYTES_READ, "rocksdb.block.cache.bytes.read"},
{BLOCK_CACHE_BYTES_WRITE, "rocksdb.block.cache.bytes.write"},
{BLOOM_FILTER_USEFUL, "rocksdb.bloom.filter.useful"},
{PERSISTENT_CACHE_HIT, "rocksdb.persistent.cache.hit"},
{PERSISTENT_CACHE_MISS, "rocksdb.persistent.cache.miss"},
{SIM_BLOCK_CACHE_HIT, "rocksdb.sim.block.cache.hit"},
{SIM_BLOCK_CACHE_MISS, "rocksdb.sim.block.cache.miss"},
{MEMTABLE_HIT, "rocksdb.memtable.hit"},
{MEMTABLE_MISS, "rocksdb.memtable.miss"},
{GET_HIT_L0, "rocksdb.l0.hit"},
{GET_HIT_L1, "rocksdb.l1.hit"},
{GET_HIT_L2_AND_UP, "rocksdb.l2andup.hit"},
{COMPACTION_KEY_DROP_NEWER_ENTRY, "rocksdb.compaction.key.drop.new"},
{COMPACTION_KEY_DROP_OBSOLETE, "rocksdb.compaction.key.drop.obsolete"},
{COMPACTION_KEY_DROP_RANGE_DEL, "rocksdb.compaction.key.drop.range_del"},
{COMPACTION_KEY_DROP_USER, "rocksdb.compaction.key.drop.user"},
{COMPACTION_RANGE_DEL_DROP_OBSOLETE,
"rocksdb.compaction.range_del.drop.obsolete"},
{NUMBER_KEYS_WRITTEN, "rocksdb.number.keys.written"},
{NUMBER_KEYS_READ, "rocksdb.number.keys.read"},
{NUMBER_KEYS_UPDATED, "rocksdb.number.keys.updated"},
{BYTES_WRITTEN, "rocksdb.bytes.written"},
{BYTES_READ, "rocksdb.bytes.read"},
{NUMBER_DB_SEEK, "rocksdb.number.db.seek"},
{NUMBER_DB_NEXT, "rocksdb.number.db.next"},
{NUMBER_DB_PREV, "rocksdb.number.db.prev"},
{NUMBER_DB_SEEK_FOUND, "rocksdb.number.db.seek.found"},
{NUMBER_DB_NEXT_FOUND, "rocksdb.number.db.next.found"},
{NUMBER_DB_PREV_FOUND, "rocksdb.number.db.prev.found"},
{ITER_BYTES_READ, "rocksdb.db.iter.bytes.read"},
{NO_FILE_CLOSES, "rocksdb.no.file.closes"},
{NO_FILE_OPENS, "rocksdb.no.file.opens"},
{NO_FILE_ERRORS, "rocksdb.no.file.errors"},
{STALL_L0_SLOWDOWN_MICROS, "rocksdb.l0.slowdown.micros"},
{STALL_MEMTABLE_COMPACTION_MICROS, "rocksdb.memtable.compaction.micros"},
{STALL_L0_NUM_FILES_MICROS, "rocksdb.l0.num.files.stall.micros"},
{STALL_MICROS, "rocksdb.stall.micros"},
{DB_MUTEX_WAIT_MICROS, "rocksdb.db.mutex.wait.micros"},
{RATE_LIMIT_DELAY_MILLIS, "rocksdb.rate.limit.delay.millis"},
{NO_ITERATORS, "rocksdb.num.iterators"},
{NUMBER_MULTIGET_CALLS, "rocksdb.number.multiget.get"},
{NUMBER_MULTIGET_KEYS_READ, "rocksdb.number.multiget.keys.read"},
{NUMBER_MULTIGET_BYTES_READ, "rocksdb.number.multiget.bytes.read"},
{NUMBER_FILTERED_DELETES, "rocksdb.number.deletes.filtered"},
{NUMBER_MERGE_FAILURES, "rocksdb.number.merge.failures"},
{BLOOM_FILTER_PREFIX_CHECKED, "rocksdb.bloom.filter.prefix.checked"},
{BLOOM_FILTER_PREFIX_USEFUL, "rocksdb.bloom.filter.prefix.useful"},
{NUMBER_OF_RESEEKS_IN_ITERATION, "rocksdb.number.reseeks.iteration"},
{GET_UPDATES_SINCE_CALLS, "rocksdb.getupdatessince.calls"},
{BLOCK_CACHE_COMPRESSED_MISS, "rocksdb.block.cachecompressed.miss"},
{BLOCK_CACHE_COMPRESSED_HIT, "rocksdb.block.cachecompressed.hit"},
{BLOCK_CACHE_COMPRESSED_ADD, "rocksdb.block.cachecompressed.add"},
{BLOCK_CACHE_COMPRESSED_ADD_FAILURES,
"rocksdb.block.cachecompressed.add.failures"},
{WAL_FILE_SYNCED, "rocksdb.wal.synced"},
{WAL_FILE_BYTES, "rocksdb.wal.bytes"},
{WRITE_DONE_BY_SELF, "rocksdb.write.self"},
{WRITE_DONE_BY_OTHER, "rocksdb.write.other"},
{WRITE_TIMEDOUT, "rocksdb.write.timeout"},
{WRITE_WITH_WAL, "rocksdb.write.wal"},
{COMPACT_READ_BYTES, "rocksdb.compact.read.bytes"},
{COMPACT_WRITE_BYTES, "rocksdb.compact.write.bytes"},
{FLUSH_WRITE_BYTES, "rocksdb.flush.write.bytes"},
{NUMBER_DIRECT_LOAD_TABLE_PROPERTIES,
"rocksdb.number.direct.load.table.properties"},
{NUMBER_SUPERVERSION_ACQUIRES, "rocksdb.number.superversion_acquires"},
{NUMBER_SUPERVERSION_RELEASES, "rocksdb.number.superversion_releases"},
{NUMBER_SUPERVERSION_CLEANUPS, "rocksdb.number.superversion_cleanups"},
{NUMBER_BLOCK_COMPRESSED, "rocksdb.number.block.compressed"},
{NUMBER_BLOCK_DECOMPRESSED, "rocksdb.number.block.decompressed"},
{NUMBER_BLOCK_NOT_COMPRESSED, "rocksdb.number.block.not_compressed"},
{MERGE_OPERATION_TOTAL_TIME, "rocksdb.merge.operation.time.nanos"},
{FILTER_OPERATION_TOTAL_TIME, "rocksdb.filter.operation.time.nanos"},
{ROW_CACHE_HIT, "rocksdb.row.cache.hit"},
{ROW_CACHE_MISS, "rocksdb.row.cache.miss"},
{READ_AMP_ESTIMATE_USEFUL_BYTES, "rocksdb.read.amp.estimate.useful.bytes"},
{READ_AMP_TOTAL_READ_BYTES, "rocksdb.read.amp.total.read.bytes"},
{NUMBER_RATE_LIMITER_DRAINS, "rocksdb.number.rate_limiter.drains"},
};
/**
* Keep adding histogram's here.
* Any histogram whould have value less than HISTOGRAM_ENUM_MAX
* Add a new Histogram by assigning it the current value of HISTOGRAM_ENUM_MAX
* Add a string representation in HistogramsNameMap below
* And increment HISTOGRAM_ENUM_MAX
*/
enum Histograms : uint32_t {
DB_GET = 0,
DB_WRITE,
COMPACTION_TIME,
SUBCOMPACTION_SETUP_TIME,
TABLE_SYNC_MICROS,
COMPACTION_OUTFILE_SYNC_MICROS,
WAL_FILE_SYNC_MICROS,
MANIFEST_FILE_SYNC_MICROS,
// TIME SPENT IN IO DURING TABLE OPEN
TABLE_OPEN_IO_MICROS,
DB_MULTIGET,
READ_BLOCK_COMPACTION_MICROS,
READ_BLOCK_GET_MICROS,
WRITE_RAW_BLOCK_MICROS,
STALL_L0_SLOWDOWN_COUNT,
STALL_MEMTABLE_COMPACTION_COUNT,
STALL_L0_NUM_FILES_COUNT,
HARD_RATE_LIMIT_DELAY_COUNT,
SOFT_RATE_LIMIT_DELAY_COUNT,
NUM_FILES_IN_SINGLE_COMPACTION,
DB_SEEK,
WRITE_STALL,
SST_READ_MICROS,
// The number of subcompactions actually scheduled during a compaction
NUM_SUBCOMPACTIONS_SCHEDULED,
// Value size distribution in each operation
BYTES_PER_READ,
BYTES_PER_WRITE,
BYTES_PER_MULTIGET,
// number of bytes compressed/decompressed
// number of bytes is when uncompressed; i.e. before/after respectively
BYTES_COMPRESSED,
BYTES_DECOMPRESSED,
COMPRESSION_TIMES_NANOS,
DECOMPRESSION_TIMES_NANOS,
HISTOGRAM_ENUM_MAX, // TODO(ldemailly): enforce HistogramsNameMap match
};
const std::vector<std::pair<Histograms, std::string>> HistogramsNameMap = {
{DB_GET, "rocksdb.db.get.micros"},
{DB_WRITE, "rocksdb.db.write.micros"},
{COMPACTION_TIME, "rocksdb.compaction.times.micros"},
{SUBCOMPACTION_SETUP_TIME, "rocksdb.subcompaction.setup.times.micros"},
{TABLE_SYNC_MICROS, "rocksdb.table.sync.micros"},
{COMPACTION_OUTFILE_SYNC_MICROS, "rocksdb.compaction.outfile.sync.micros"},
{WAL_FILE_SYNC_MICROS, "rocksdb.wal.file.sync.micros"},
{MANIFEST_FILE_SYNC_MICROS, "rocksdb.manifest.file.sync.micros"},
{TABLE_OPEN_IO_MICROS, "rocksdb.table.open.io.micros"},
{DB_MULTIGET, "rocksdb.db.multiget.micros"},
{READ_BLOCK_COMPACTION_MICROS, "rocksdb.read.block.compaction.micros"},
{READ_BLOCK_GET_MICROS, "rocksdb.read.block.get.micros"},
{WRITE_RAW_BLOCK_MICROS, "rocksdb.write.raw.block.micros"},
{STALL_L0_SLOWDOWN_COUNT, "rocksdb.l0.slowdown.count"},
{STALL_MEMTABLE_COMPACTION_COUNT, "rocksdb.memtable.compaction.count"},
{STALL_L0_NUM_FILES_COUNT, "rocksdb.num.files.stall.count"},
{HARD_RATE_LIMIT_DELAY_COUNT, "rocksdb.hard.rate.limit.delay.count"},
{SOFT_RATE_LIMIT_DELAY_COUNT, "rocksdb.soft.rate.limit.delay.count"},
{NUM_FILES_IN_SINGLE_COMPACTION, "rocksdb.numfiles.in.singlecompaction"},
{DB_SEEK, "rocksdb.db.seek.micros"},
{WRITE_STALL, "rocksdb.db.write.stall"},
{SST_READ_MICROS, "rocksdb.sst.read.micros"},
{NUM_SUBCOMPACTIONS_SCHEDULED, "rocksdb.num.subcompactions.scheduled"},
{BYTES_PER_READ, "rocksdb.bytes.per.read"},
{BYTES_PER_WRITE, "rocksdb.bytes.per.write"},
{BYTES_PER_MULTIGET, "rocksdb.bytes.per.multiget"},
{BYTES_COMPRESSED, "rocksdb.bytes.compressed"},
{BYTES_DECOMPRESSED, "rocksdb.bytes.decompressed"},
{COMPRESSION_TIMES_NANOS, "rocksdb.compression.times.nanos"},
{DECOMPRESSION_TIMES_NANOS, "rocksdb.decompression.times.nanos"},
};
struct HistogramData {
double median;
double percentile95;
double percentile99;
double average;
double standard_deviation;
// zero-initialize new members since old Statistics::histogramData()
// implementations won't write them.
double max = 0.0;
};
enum StatsLevel {
// Collect all stats except time inside mutex lock AND time spent on
// compression.
kExceptDetailedTimers,
// Collect all stats except the counters requiring to get time inside the
// mutex lock.
kExceptTimeForMutex,
// Collect all stats, including measuring duration of mutex operations.
// If getting time is expensive on the platform to run, it can
// reduce scalability to more threads, especially for writes.
kAll,
};
// Analyze the performance of a db
class Statistics {
public:
virtual ~Statistics() {}
virtual uint64_t getTickerCount(uint32_t tickerType) const = 0;
virtual void histogramData(uint32_t type,
HistogramData* const data) const = 0;
virtual std::string getHistogramString(uint32_t type) const { return ""; }
virtual void recordTick(uint32_t tickerType, uint64_t count = 0) = 0;
virtual void setTickerCount(uint32_t tickerType, uint64_t count) = 0;
virtual uint64_t getAndResetTickerCount(uint32_t tickerType) = 0;
virtual void measureTime(uint32_t histogramType, uint64_t time) = 0;
// String representation of the statistic object.
virtual std::string ToString() const {
// Do nothing by default
return std::string("ToString(): not implemented");
}
// Override this function to disable particular histogram collection
virtual bool HistEnabledForType(uint32_t type) const {
return type < HISTOGRAM_ENUM_MAX;
}
StatsLevel stats_level_ = kExceptDetailedTimers;
};
// Create a concrete DBStatistics object
std::shared_ptr<Statistics> CreateDBStatistics();
} // namespace rocksdb
#endif // STORAGE_ROCKSDB_INCLUDE_STATISTICS_H_
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