RocksDB笔记 -- Options File

最近开完第一次组会, 准备学习RocksDB以及如何配置文件.

RocksDB数据库提供一些函数调用来帮助Options File:

1. 将一系列选项写入一个文件中: DB::Open(), DB::SetOptions(), DB::CreateColumnFamily(), DB::DropColumnFamily() .

2. 加载文件中的配置选项: LoadLatestOptions(), LoadOptionsFromFile() .

3. 检查两个配置选项集合的兼容性: CheckOptionsCompatibility() .

RocksDB的options file是文本文件, 它是INI文件格式. 

Tips:

1. 可以设置ConfigOptions.ignore_unknown_options=true可以忽略掉未知的文件配置选项. 该设置默认为false.

RocksDB Options File格式(rocksdb/examples/rocksdb_option_file_example.ini):

# This is a RocksDB option file.
#
# A typical RocksDB options file has four sections, which are
# Version section, DBOptions section, at least one CFOptions
# section, and one TableOptions section for each column family.
# The RocksDB options file in general follows the basic INI
# file format with the following extensions / modifications:
#
#  * Escaped characters
#    We escaped the following characters:
#     - \n -- line feed - new line
#     - \r -- carriage return
#     - \\ -- backslash \
#     - \: -- colon symbol :
#     - \# -- hash tag #
#  * Comments
#    We support # style comments.  Comments can appear at the ending
#    part of a line.
#  * Statements
#    A statement is of the form option_name = value.
#    Each statement contains a '=', where extra white-spaces
#    are supported. However, we don't support multi-lined statement.
#    Furthermore, each line can only contain at most one statement.
#  * Sections
#    Sections are of the form [SecitonTitle "SectionArgument"],
#    where section argument is optional.
#  * List
#    We use colon-separated string to represent a list.
#    For instance, n1:n2:n3:n4 is a list containing four values.
#
# Below is an example of a RocksDB options file:
[Version]
  rocksdb_version=4.3.0
  options_file_version=1.1

[DBOptions]
  stats_dump_period_sec=600
  max_manifest_file_size=18446744073709551615
  bytes_per_sync=8388608
  delayed_write_rate=2097152
  WAL_ttl_seconds=0
  WAL_size_limit_MB=0
  max_subcompactions=1
  wal_dir=
  wal_bytes_per_sync=0
  db_write_buffer_size=0
  keep_log_file_num=1000
  table_cache_numshardbits=4
  max_file_opening_threads=1
  writable_file_max_buffer_size=1048576
  random_access_max_buffer_size=1048576
  use_fsync=false
  max_total_wal_size=0
  max_open_files=-1
  skip_stats_update_on_db_open=false
  max_background_compactions=16
  manifest_preallocation_size=4194304
  max_background_flushes=7
  is_fd_close_on_exec=true
  max_log_file_size=0
  advise_random_on_open=true
  create_missing_column_families=false
  paranoid_checks=true
  delete_obsolete_files_period_micros=21600000000
  log_file_time_to_roll=0
  compaction_readahead_size=0
  create_if_missing=false
  use_adaptive_mutex=false
  enable_thread_tracking=false
  allow_fallocate=true
  error_if_exists=false
  recycle_log_file_num=0
  db_log_dir=
  skip_log_error_on_recovery=false
  new_table_reader_for_compaction_inputs=true
  allow_mmap_reads=false
  allow_mmap_writes=false
  use_direct_reads=false
  use_direct_writes=false


[CFOptions "default"]
  compaction_style=kCompactionStyleLevel
  compaction_filter=nullptr
  num_levels=6
  table_factory=BlockBasedTable
  comparator=leveldb.BytewiseComparator
  max_sequential_skip_in_iterations=8
  max_bytes_for_level_base=1073741824
  memtable_prefix_bloom_probes=6
  memtable_prefix_bloom_bits=0
  memtable_prefix_bloom_huge_page_tlb_size=0
  max_successive_merges=0
  arena_block_size=16777216
  min_write_buffer_number_to_merge=1
  target_file_size_multiplier=1
  source_compaction_factor=1
  max_bytes_for_level_multiplier=8
  max_bytes_for_level_multiplier_additional=2:3:5
  compaction_filter_factory=nullptr
  max_write_buffer_number=8
  level0_stop_writes_trigger=20
  compression=kSnappyCompression
  level0_file_num_compaction_trigger=4
  purge_redundant_kvs_while_flush=true
  max_write_buffer_size_to_maintain=0
  memtable_factory=SkipListFactory
  max_grandparent_overlap_factor=8
  expanded_compaction_factor=25
  hard_pending_compaction_bytes_limit=137438953472
  inplace_update_num_locks=10000
  level_compaction_dynamic_level_bytes=true
  level0_slowdown_writes_trigger=12
  filter_deletes=false
  verify_checksums_in_compaction=true
  min_partial_merge_operands=2
  paranoid_file_checks=false
  target_file_size_base=134217728
  optimize_filters_for_hits=false
  merge_operator=PutOperator
  compression_per_level=kNoCompression:kNoCompression:kNoCompression:kSnappyCompression:kSnappyCompression:kSnappyCompression
  compaction_measure_io_stats=false
  prefix_extractor=nullptr
  bloom_locality=0
  write_buffer_size=134217728
  disable_auto_compactions=false
  inplace_update_support=false

[TableOptions/BlockBasedTable "default"]
  format_version=2
  whole_key_filtering=true
  no_block_cache=false
  checksum=kCRC32c
  filter_policy=rocksdb.BuiltinBloomFilter
  block_size_deviation=10
  block_size=8192
  block_restart_interval=16
  cache_index_and_filter_blocks=false
  pin_l0_filter_and_index_blocks_in_cache=false
  pin_top_level_index_and_filter=false
  index_type=kBinarySearch
  flush_block_policy_factory=FlushBlockBySizePolicyFactory

参考: 

RocksDB Options File · facebook/rocksdb Wiki · GitHub