RocksDB Config

Learn how to configure namespace in TiKV.

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TiKV uses RocksDB as its underlying storage engine for storing both Raft logs and KV (key-value) pairs.

RocksDB was chosen for TiKV because it provides a highly customizable persistent key-value store that can be tuned to run in a variety of production environments, including pure memory, Flash, hard disks, or HDFS, it supports various compression algorithms, and it provides solid tools for production support and debugging.

TiKV creates two RocksDB instances on each Node:

  • A rocksdb instance that stores most TiKV data
  • A raftdb that stores Raft logs and has a single column family called raftdb.defaultcf

The rocksdb instance has three column families:

Column familyPurpose
rocksdb.defaultcfStores actual KV pairs for TiKV
rocksdb.writecfStores commit information in the MVCC model

RocksDB can be configured on a per-column-family basis. Here’s an example:

[rocksdb]
max-background-jobs = 8

RocksDB configuration options

max-background-jobs

  • The number of background threads in RocksDB
  • Default value: 8
  • Minimum value: 1

max-background-flushes

  • The maximum number of concurrent background memtable flush jobs
  • Default value: 2
  • Minimum value: 1

max-sub-compactions

  • The number of sub-compaction operations performed concurrently in RocksDB
  • Default value: 3
  • Minimum value: 1

max-open-files

  • The total number of files that RocksDB can open
  • Default value: 40960
  • Minimum value: -1

max-manifest-file-size

  • The maximum size of a RocksDB Manifest file
  • Default value: 128MB
  • Minimum value: 0
  • Unit: B|KB|MB|GB

create-if-missing

  • Determines whether to automatically create a DB switch
  • Default value: true

wal-recovery-mode

  • WAL recovery mode
  • Optional values: 0 (TolerateCorruptedTailRecords), 1 (AbsoluteConsistency), 2 (PointInTimeRecovery), 3 (SkipAnyCorruptedRecords)
  • Default value: 2
  • Minimum value: 0
  • Maximum value: 3

wal-dir

  • The directory in which WAL files are stored
  • Default value: /tmp/tikv/store

wal-ttl-seconds

  • The living time of the archived WAL files. When the value is exceeded, the system deletes these files.
  • Default value: 0
  • Minimum value: 0
  • unit: second

wal-size-limit

  • The size limit of the archived WAL files. When the value is exceeded, the system deletes these files.
  • Default value: 0
  • Minimum value: 0
  • Unit: B|KB|MB|GB

enable-statistics

  • Determines whether to automatically optimize the configuration of Rate LImiter
  • Default value: false

stats-dump-period

  • Enables or disables Pipelined Write
  • Default value: true

compaction-readahead-size

  • The size of readahead when compaction is being performed
  • Default value: 0
  • Minimum value: 0
  • Unit: B|KB|MB|GB

writable-file-max-buffer-size

  • The maximum buffer size used in WritableFileWrite
  • Default value: 1MB
  • Minimum value: 0
  • Unit: B|KB|MB|GB

use-direct-io-for-flush-and-compaction

  • Determines whether to use O_DIRECT for both reads and writes in background flush and compactions
  • Default value: false

rate-bytes-per-sec

  • The maximum rate permitted by Rate Limiter
  • Default value: 0
  • Minimum value: 0
  • Unit: Bytes

rate-limiter-mode

  • Rate LImiter mode
  • Optional values: 1 (ReadOnly), 2 (WriteOnly), 3 (AllIo)
  • Default value: 2
  • Minimum value: 1
  • Maximum value: 3

auto-tuned

  • Determines whether to automatically optimize the configuration of the Rate LImiter
  • Default value: false

enable-pipelined-write

  • Enables or disables Pipelined Write
  • Default value: true

bytes-per-sync

  • The rate at which OS incrementally synchronizes files to disk while these files are being written asynchronously
  • Default value: 1MB
  • Minimum value: 0
  • Unit: B|KB|MB|GB

wal-bytes-per-sync

  • The rate at which OS incrementally synchronizes WAL files to disk while the WAL files are being written
  • Default value: 512KB
  • Minimum value: 0
  • Unit: B|KB|MB|GB

info-log-max-size

  • The maximum size of Info log
  • Default value: 1GB
  • Minimum value: 0
  • Unit: B|KB|MB|GB

info-log-roll-time

  • The time interval at which Info logs are truncated. If the value is 0s, logs are not truncated.
  • Default value: 0s

info-log-keep-log-file-num

  • The maximum number of kept log files
  • Default value: 10
  • Minimum value: 0

info-log-dir

  • The directory in which logs are stored
  • Default value: "”