# TiDB Lightning Configuration

This document provides samples for global configuration, task configuration, and TiKV Importer configuration in TiDB Lightning, and describes the usage of command-line parameters.

## Configuration files

TiDB Lightning has two configuration classes: “global” and “task”, and they have compatible structures. Their distinction arises only when the server mode is enabled. When server mode is disabled (the default), TiDB Lightning will only execute one task, and the same configuration file is used for both global and task configurations.

### TiDB Lightning (Global)

### tidb-lightning global configuration

[lightning]
# The HTTP port for the web interface and Prometheus metrics pulling (0 to disable).

# Toggle server mode and use of the web interface.
# See the "TiDB Lightning Web Interface" section for details.
server-mode = false

# Logging
level = "info"
file = "tidb-lightning.log"
max-size = 128 # MB
max-days = 28
max-backups = 14


### tidb-lightning task configuration

[lightning]
# Checks whether the cluster satisfies the minimum requirement before starting.
#check-requirements = true

# The maximum number of engines to be opened concurrently.
# Each table is split into one "index engine" to store indices, and multiple
# "data engines" to store row data. These settings control the maximum
# concurrent number for each type of engines.
# These values affect the memory and disk usage of tikv-importer.
# The sum of these two values must not exceed the max-open-engines setting
# for tikv-importer.
index-concurrency = 2
table-concurrency = 6

# The concurrency number of data. It is set to the number of logical CPU
# cores by default. When deploying together with other components, you can
# set it to 75% of the size of logical CPU cores to limit the CPU usage.
#region-concurrency =

# The maximum I/O concurrency. Excessive I/O concurrency causes an increase in
# I/O latency because the disk's internal buffer is frequently refreshed,
# which causes the cache miss and slows down the read speed. Depending on the storage
# medium, this value might need to be adjusted for optimal performance.
io-concurrency = 5

[checkpoint]
# Whether to enable checkpoints.
# While importing data, TiDB Lightning records which tables have been imported, so
# even if Lightning or another component crashes, you can start from a known
# good state instead of redoing everything.
enable = true
# The schema name (database name) to store the checkpoints.
schema = "tidb_lightning_checkpoint"
# Where to store the checkpoints.
#  - file:  store as a local file.
#  - mysql: store into a remote MySQL-compatible database
driver = "file"
# The data source name (DSN) indicating the location of the checkpoint storage.
# For the "file" driver, the DSN is a path. If the path is not specified, Lightning would
# default to "/tmp/CHECKPOINT_SCHEMA.pb".
# For the "mysql" driver, the DSN is a URL in the form of "USER:PASS@tcp(HOST:PORT)/".
# If the URL is not specified, the TiDB server from the [tidb] section is used to
# store the checkpoints. You should specify a different MySQL-compatible
# database server to reduce the load of the target TiDB cluster.
#dsn = "/tmp/tidb_lightning_checkpoint.pb"
# Whether to keep the checkpoints after all data are imported. If false, the
# checkpoints will be deleted. Keeping the checkpoints can aid debugging but
#keep-after-success = false

[tikv-importer]
# Delivery back end, can be "importer" or "tidb".
# backend = "importer"
# The listening address of tikv-importer when back end is "importer". Change it to the actual address.
# Action to do when trying to insert a duplicated entry in the "tidb" back end.
#  - replace: new entry replaces existing entry
#  - ignore:  keep existing entry, ignore new entry
#on-duplicate = "replace"

[mydumper]
# Block size for file reading. Keep it longer than the longest string of
# the data source.
read-block-size = 65536 # Byte (default = 64 KB)

# Minimum size (in terms of source data file) of each batch of import.
# TiDB Lightning splits a large table into multiple data engine files according to this size.
batch-size = 107_374_182_400 # Byte (default = 100 GB)

# The engine file needs to be imported sequentially. Due to parallel processing,
# multiple data engines will be imported at nearly the same time, and this
# creates a queue and wastes resources. Therefore, Lightning slightly
# increases the size of the first few batches to properly distribute
# resources. The scale up factor is controlled by this parameter, which
# expresses the ratio of duration between the "import" and "write" steps
# with full concurrency. This can be calculated by using the ratio
# (import duration/write duration) of a single table of size around 1 GB.
# The exact timing can be found in the log. If "import" is faster, the batch
# size variance is smaller, and a ratio of zero means a uniform batch size.
# This value should be in the range (0 <= batch-import-ratio < 1).
batch-import-ratio = 0.75

# mydumper local source data directory.
data-source-dir = "/data/my_database"
# If no-schema is set to true, tidb-lightning assumes that the table skeletons
# already exist on the target TiDB cluster, and will not execute the CREATE
# TABLE statements.
no-schema = false
# The character set of the schema files, containing CREATE TABLE statements;
# only supports one of:
#  - utf8mb4: the schema files must be encoded as UTF-8, otherwise Lightning
#             will emit errors
#  - gb18030: the schema files must be encoded as GB-18030, otherwise
#             Lightning will emit errors
#  - auto:    (default) automatically detects whether the schema is UTF-8 or
#             GB-18030. An error is reported if the encoding is neither.
#  - binary:  do not try to decode the schema files
# Note that the *data* files are always parsed as binary regardless of
# schema encoding.
character-set = "auto"

# Configures how CSV files are parsed.
[mydumper.csv]
# Separator between fields, should be an ASCII character.
separator = ','
# Quoting delimiter, can either be an ASCII character or empty string.
delimiter = '"'
# Whether the CSV files contain a header.
# If header is true, the first line will be skipped.
# Whether the CSV contains any NULL value.
# If not-null is true, all columns from CSV cannot be NULL.
not-null = false
# When not-null is false (i.e. CSV can contain NULL),
# fields equal to this value will be treated as NULL.
null = '\N'
# Whether to interpret backslash escapes inside fields.
backslash-escape = true
# If a line ends with a separator, remove it.
trim-last-separator = false

[tidb]
# Configuration of any TiDB server from the cluster.
host = "172.16.31.1"
port = 4000
user = "root"
# Table schema information is fetched from TiDB via this status-port.
status-port = 10080
# Address of any PD server from the cluster.
# tidb-lightning imports TiDB as a library and generates some logs itself.
# This setting controls the log level of the TiDB library.
log-level = "error"

# Sets the TiDB session variable to speed up the Checksum and Analyze operations.
# See https://pingcap.com/docs/dev/reference/performance/statistics/#control-analyze-concurrency
# for the meaning of each setting
build-stats-concurrency = 20
distsql-scan-concurrency = 100
index-serial-scan-concurrency = 20
checksum-table-concurrency = 16

# The default SQL mode used to parse and execute the SQL statements.
sql-mode = "STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION"

# When data importing is complete, tidb-lightning can automatically perform
# the Checksum, Compact and Analyze operations. It is recommended to leave
# these as true in the production environment.
# The execution order: Checksum -> Analyze
[post-restore]
# Performs ADMIN CHECKSUM TABLE <table> for each table to verify data integrity.
checksum = true
# If the value is set to true, a level-1 compaction is performed
# every time a table is imported.
# The default value is false.
level-1-compact = false
# If the value is set to true, a full compaction on the whole
# TiKV cluster is performed at the end of the import.
# The default value is false.
compact = false
# Performs ANALYZE TABLE <table> for each table.
analyze = true

# Configures the background periodic actions.
# Supported units: h (hour), m (minute), s (second).
[cron]
# Duration between which Lightning automatically refreshes the import mode
# status. Should be shorter than the corresponding TiKV setting.
switch-mode = "5m"
# Duration between which an import progress is printed to the log.
log-progress = "5m"

# Table filter options. See the corresponding section for details.
#[black-white-list]
# ...


### TiKV Importer

# TiKV Importer configuration file template.

# Log file.
log-file = "tikv-importer.log"
# Log level: trace, debug, info, warn, error, off.
log-level = "info"

[server]
# The listening address of tikv-importer. tidb-lightning needs to connect to
# this address to write data.
# Size of the thread pool for the gRPC server.
grpc-concurrency = 16

[metric]
# The Prometheus client push job name.
job = "tikv-importer"
# The Prometheus client push interval.
interval = "15s"

[rocksdb]
# The maximum number of concurrent background jobs.
max-background-jobs = 32

[rocksdb.defaultcf]
# Amount of data to build up in memory before flushing data to the disk.
write-buffer-size = "1GB"
# The maximum number of write buffers that are built up in memory.
max-write-buffer-number = 8

# The compression algorithms used in different levels.
# The algorithm at level-0 is used to compress KV data.
# The algorithm at level-6 is used to compress SST files.
# The algorithms at level-1 to level-5 are unused for now.
compression-per-level = ["lz4", "no", "no", "no", "no", "no", "lz4"]

[rocksdb.writecf]
# (same as above)
compression-per-level = ["lz4", "no", "no", "no", "no", "no", "lz4"]

[import]
# The directory to store engine files.
import-dir = "/mnt/ssd/data.import/"
# Number of threads to handle RPC requests.
# Number of concurrent import jobs.
num-import-jobs = 24
# Maximum duration to prepare Regions.
#max-prepare-duration = "5m"
# Split Regions into this size according to the importing data.
#region-split-size = "512MB"
# Stream channel window size. The stream will be blocked on channel full.
#stream-channel-window = 128
# Maximum number of open engines.
max-open-engines = 8
# Maximum upload speed (bytes per second) from Importer to TiKV.
# Minimum ratio of available space on the target store: store_available_space/store_capacity.
# Importer pauses uploading SST if the availability ratio of the target store is less than this
# value, to allow enough time for PD to balance Regions.
min-available-ratio = 0.05


## Command line parameters

### Usage of tidb-lightning

Parameter Explanation Corresponding setting
–config file Reads global configuration from file. If not specified, the default configuration would be used.
-V Prints program version
-d directory Directory of the data dump to read from mydumper.data-source-dir
-L level Log level: debug, info, warn, error, fatal (default = info) lightning.log-level
–backend backend Delivery back end (importer or tidb) tikv-importer.backend
–log-file file Log file path lightning.log-file
–status-addr ip:port Listening address of the TiDB Lightning server lightning.status-port
–importer host:port Address of TiKV Importer tikv-importer.addr
–pd-urls host:port PD endpoint address tidb.pd-addr
–tidb-host host TiDB server host tidb.host
–tidb-port port TiDB server port (default = 4000) tidb.port
–tidb-status port TiDB status port (default = 10080) tidb.status-port
–tidb-user user User name to connect to TiDB tidb.user

If a command line parameter and the corresponding setting in the configuration file are both provided, the command line parameter will be used. For example, running ./tidb-lightning -L debug --config cfg.toml would always set the log level to “debug” regardless of the content of cfg.toml.

## Usage of tidb-lightning-ctl

This tool can execute various actions given one of the following parameters:

Parameter Explanation
–compact Performs a full compaction
–switch-mode mode Switches every TiKV store to the given mode: normal, import
–import-engine uuid Imports the closed engine file from TiKV Importer into the TiKV cluster
–cleanup-engine uuid Deletes the engine file from TiKV Importer
–checkpoint-dump folder Dumps current checkpoint as CSVs into the folder
–checkpoint-error-destroy tablename Removes the checkpoint and drops the table if it caused error
–checkpoint-error-ignore tablename Ignores any error recorded in the checkpoint involving the given table
–checkpoint-remove tablename Unconditionally removes the checkpoint of the table

The tablename must either be a qualified table name in the form db.tbl (including the backquotes), or the keyword “all”.

Additionally, all parameters of tidb-lightning described in the section above are valid in tidb-lightning-ctl.

## Usage of tikv-importer

Parameter Explanation Corresponding setting
-C, –config file Reads configuration from file. If not specified, the default configuration would be used.
-V, –version Prints program version
-A, –addr ip:port Listening address of the TiKV Importer server server.addr
–import-dir dir Stores engine files in this directory import.import-dir
–log-level level Log level: trace, debug, info, warn, error, off log-level
–log-file file Log file path log-file