Datanode

The greptime datanode command provides subcommands for managing and benchmarking datanode instances.

start

Start the datanode service.

Options

You can list all the options from the following command:

greptime datanode start --help

Option	Description
-c/--config-file	The configuration file for datanode
--data-home	Database storage root directory
--env-prefix <ENV_PREFIX>	The prefix of environment variables, default is GREPTIMEDB_DATANODE
--http-addr <HTTP_ADDR>	HTTP server address
--http-timeout <HTTP_TIMEOUT>	HTTP request timeout in seconds
--metasrv-addrs <METASRV_ADDR>	Metasrv address list
--node-id <NODE_ID>	The datanode ID
--rpc-bind-addr <RPC_BIND_ADDR>	The address to bind the gRPC server
--rpc-server-addr <RPC_SERVER_ADDR>	The address advertised to the metasrv, and used for connections from outside the host. If left empty or unset, the server will automatically use the IP address of the first network interface on the host, with the same port number as the one specified in rpc_bind_addr
--wal-dir <WAL_DIR>	The directory of WAL

All the addr options are in the form of ip:port.

Examples

Start service with configurations

Starts a datanode instance with customized configurations:

greptime datanode start -c config/datanode.example.toml

Starts a datanode instance with command line arguments specifying the gRPC service address, the MySQL service address, the address of the metasrv, and the node id of the instance:

greptime datanode start --rpc-bind-addr=0.0.0.0:4001 --mysql-addr=0.0.0.0:4002 --metasrv-addrs=0.0.0.0:3002 --node-id=1

The datanode.example.toml configuration file comes from the config directory of the [GreptimeDB](https://github.com/GreptimeTeam/greptimedb/) repository. You can find more example configuration files there. The -c option specifies the configuration file, for more information check Configuration.

objbench

The objbench subcommand is a benchmarking tool for measuring read/write performance of specific files on object storage. This is useful for diagnosing performance issues and testing storage layer performance.

Options

Option	Description
--config <FILE>	Path to the datanode configuration file (TOML format)
--source <PATH>	Source SST file path in object storage (e.g., data/greptime/public/1024/1024_0000000000/metadata/<uuid>.parquet)
-v/--verbose	Enable verbose output
--pprof-file <FILE>	Output file path for pprof flamegraph (enables profiling). Generates an SVG flamegraph file

Examples

Basic benchmark

Measure the read/write performance of a specific file:

greptime datanode objbench --config ./datanode.toml --source data/greptime/public/1024/1024_0000000000/metadata/8fb41bc7-a106-4b9e-879b-392da799f958.parquet

Benchmark with profiling

Measure performance and generate a flamegraph for performance analysis:

greptime datanode objbench --config ./datanode.toml --source data/greptime/public/1024/1024_0000000000/metadata/8fb41bc7-a106-4b9e-879b-392da799f958.parquet --pprof-file=./flamegraph.svg

This will generate a flamegraph in SVG format that can be opened in a web browser for performance analysis.

scanbench

The scanbench subcommand benchmarks region scans directly from storage.

Options

Option	Description
--config <FILE>	Path to the datanode/standalone configuration file (TOML format).
--region-id <REGION_ID>	Region ID in one of: <u64> (for example, 4398046511104) or <table_id>:<region_number> (for example, 1024:0).
--table-dir <TABLE_DIR>	Table directory used in open request (for example, greptime/public/1024).
--scanner <seq|unordered|series>	Scan strategy. Defaults to seq.
--scan-config <FILE>	JSON file used to tune the scan request.
--parallelism <N>	Simulated scan parallelism. Defaults to 1.
--iterations <N>	Benchmark iterations. Defaults to 1.
--path-type <bare|data|metadata>	Region path type. Defaults to bare.
--force-flat-format	Force reading the region in flat format. Disabled by default.
--enable-wal	Enable WAL replay when opening the region. Disabled by default.
--pprof-file <FILE>	Output file path for pprof flamegraph (Unix only).
--pprof-after-warmup	Start pprof after the first iteration (use the first iteration as warmup). Requires --pprof-file. Disabled by default.
-v/--verbose	Enable verbose output.

scan-config JSON

{
  "projection_names": ["host", "cpu"],
  "filters": ["host = 'web-1'", "cpu > 80"],
  "series_row_selector": "last_row"
}

Notes:

• All fields are optional.
• Use either projection (indexes) or projection_names (column names), not both.
• projection_names uses exact (case-sensitive) column name matching.
• filters should be SQL expressions (not full SQL statements).
• series_row_selector currently supports only last_row.

Examples

Default sequential scan

greptime datanode scanbench --config ./datanode.toml --region-id 1024:0 --table-dir greptime/public/1024

Unordered scan with parallelism

greptime datanode scanbench --config ./datanode.toml --region-id 1024:0 --table-dir greptime/public/1024 --scanner unordered --parallelism 8 --iterations 5

Series scan on metric engine data directory

greptime datanode scanbench --config ./datanode.toml --region-id 1024:0 --table-dir data/greptime/public/1024 --parallelism 16 --scan-config ./scanconfig.json --scanner series --path-type data --iterations 10

Example scanconfig.json:

{
  "projection_names": ["greptime_timestamp", "greptime_value", "az", "hostname", "region", "__tsid"],
  "filters": [
    "mode = 'idle'",
    "region = 'us-west-2'",
    "greptime_timestamp >= 1742550540001",
    "greptime_timestamp <= 1742552400000",
    "__table_id = 1182"
  ]
}

Profile after warmup iteration

greptime datanode scanbench --config ./datanode.toml --region-id 1024:0 --table-dir greptime/public/1024 --iterations 5 --pprof-file ./scanbench.svg --pprof-after-warmup