diff --git a/.github/workflows/develop.yml b/.github/workflows/develop.yml
index 1f6f050df5..52e57f68cd 100644
--- a/.github/workflows/develop.yml
+++ b/.github/workflows/develop.yml
@@ -33,12 +33,17 @@ env:
   RUST_TOOLCHAIN: nightly-2023-12-19
 
 jobs:
-  typos:
-    name: Spell Check with Typos
+  check-typos-and-docs:
+    name: Check typos and docs
     runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
       - uses: crate-ci/typos@v1.13.10
+      - name: Check the config docs
+        run: |
+          make config-docs && \
+          git diff --name-only --exit-code ./config/config.md  \
+          || (echo "'config/config.md' is not up-to-date, please run 'make config-docs'." && exit 1)
 
   check:
     name: Check
diff --git a/Makefile b/Makefile
index 28077b6960..4826bbb5dd 100644
--- a/Makefile
+++ b/Makefile
@@ -192,6 +192,16 @@ run-it-in-container: start-etcd ## Run integration tests in dev-builder.
 	-w /greptimedb ${IMAGE_REGISTRY}/${IMAGE_NAMESPACE}/dev-builder-${BASE_IMAGE}:latest \
 	make test sqlness-test BUILD_JOBS=${BUILD_JOBS}
 
+##@ Docs
+config-docs: ## Generate configuration documentation from toml files.
+	docker run --rm \
+    -v ${PWD}:/greptimedb \
+    -w /greptimedb/config \
+    toml2docs/toml2docs:latest \
+    -p '##' \
+    -t ./config-docs-template.md \
+    -o ./config.md
+
 ##@ General
 
 # The help target prints out all targets with their descriptions organized
diff --git a/config/config-docs-template.md b/config/config-docs-template.md
new file mode 100644
index 0000000000..8fe10780f5
--- /dev/null
+++ b/config/config-docs-template.md
@@ -0,0 +1,19 @@
+# Configurations
+
+## Standalone Mode
+
+{{ toml2docs "./standalone.example.toml" }}
+
+## Cluster Mode
+
+### Frontend
+
+{{ toml2docs "./frontend.example.toml" }}
+
+### Metasrv
+
+{{ toml2docs "./metasrv.example.toml" }}
+
+### Datanode
+
+{{ toml2docs "./datanode.example.toml" }}
diff --git a/config/config.md b/config/config.md
new file mode 100644
index 0000000000..50c3f967b2
--- /dev/null
+++ b/config/config.md
@@ -0,0 +1,376 @@
+# Configurations
+
+## Standalone Mode
+
+| Key | Type | Default | Descriptions |
+| --- | -----| ------- | ----------- |
+| `mode` | String | `standalone` | The running mode of the datanode. It can be `standalone` or `distributed`. |
+| `enable_telemetry` | Bool | `true` | Enable telemetry to collect anonymous usage data. |
+| `default_timezone` | String | `None` | The default timezone of the server. |
+| `http` | -- | -- | The HTTP server options. |
+| `http.addr` | String | `127.0.0.1:4000` | The address to bind the HTTP server. |
+| `http.timeout` | String | `30s` | HTTP request timeout. |
+| `http.body_limit` | String | `64MB` | HTTP request body limit.<br/>Support the following units are supported: `B`, `KB`, `KiB`, `MB`, `MiB`, `GB`, `GiB`, `TB`, `TiB`, `PB`, `PiB`. |
+| `grpc` | -- | -- | The gRPC server options. |
+| `grpc.addr` | String | `127.0.0.1:4001` | The address to bind the gRPC server. |
+| `grpc.runtime_size` | Integer | `8` | The number of server worker threads. |
+| `mysql` | -- | -- | MySQL server options. |
+| `mysql.enable` | Bool | `true` | Whether to enable. |
+| `mysql.addr` | String | `127.0.0.1:4002` | The addr to bind the MySQL server. |
+| `mysql.runtime_size` | Integer | `2` | The number of server worker threads. |
+| `mysql.tls` | -- | -- | -- |
+| `mysql.tls.mode` | String | `disable` | TLS mode, refer to https://www.postgresql.org/docs/current/libpq-ssl.html<br/>- `disable` (default value)<br/>- `prefer`<br/>- `require`<br/>- `verify-ca`<br/>- `verify-full` |
+| `mysql.tls.cert_path` | String | `None` | Certificate file path. |
+| `mysql.tls.key_path` | String | `None` | Private key file path. |
+| `mysql.tls.watch` | Bool | `false` | Watch for Certificate and key file change and auto reload |
+| `postgres` | -- | -- | PostgresSQL server options. |
+| `postgres.enable` | Bool | `true` | Whether to enable |
+| `postgres.addr` | String | `127.0.0.1:4003` | The addr to bind the PostgresSQL server. |
+| `postgres.runtime_size` | Integer | `2` | The number of server worker threads. |
+| `postgres.tls` | -- | -- | PostgresSQL server TLS options, see `mysql_options.tls` section. |
+| `postgres.tls.mode` | String | `disable` | TLS mode. |
+| `postgres.tls.cert_path` | String | `None` | Certificate file path. |
+| `postgres.tls.key_path` | String | `None` | Private key file path. |
+| `postgres.tls.watch` | Bool | `false` | Watch for Certificate and key file change and auto reload |
+| `opentsdb` | -- | -- | OpenTSDB protocol options. |
+| `opentsdb.enable` | Bool | `true` | Whether to enable |
+| `opentsdb.addr` | String | `127.0.0.1:4242` | OpenTSDB telnet API server address. |
+| `opentsdb.runtime_size` | Integer | `2` | The number of server worker threads. |
+| `influxdb` | -- | -- | InfluxDB protocol options. |
+| `influxdb.enable` | Bool | `true` | Whether to enable InfluxDB protocol in HTTP API. |
+| `prom_store` | -- | -- | Prometheus remote storage options |
+| `prom_store.enable` | Bool | `true` | Whether to enable Prometheus remote write and read in HTTP API. |
+| `prom_store.with_metric_engine` | Bool | `true` | Whether to store the data from Prometheus remote write in metric engine. |
+| `wal` | -- | -- | The WAL options. |
+| `wal.provider` | String | `raft_engine` | The provider of the WAL.<br/>- `raft_engine`: the wal is stored in the local file system by raft-engine.<br/>- `kafka`: it's remote wal that data is stored in Kafka. |
+| `wal.dir` | String | `None` | The directory to store the WAL files.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.file_size` | String | `256MB` | The size of the WAL segment file.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.purge_threshold` | String | `4GB` | The threshold of the WAL size to trigger a flush.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.purge_interval` | String | `10m` | The interval to trigger a flush.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.read_batch_size` | Integer | `128` | The read batch size.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.sync_write` | Bool | `false` | Whether to use sync write.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.enable_log_recycle` | Bool | `true` | Whether to reuse logically truncated log files.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.prefill_log_files` | Bool | `false` | Whether to pre-create log files on start up.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.sync_period` | String | `10s` | Duration for fsyncing log files.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.broker_endpoints` | Array | -- | The Kafka broker endpoints.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.max_batch_size` | String | `1MB` | The max size of a single producer batch.<br/>Warning: Kafka has a default limit of 1MB per message in a topic.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.linger` | String | `200ms` | The linger duration of a kafka batch producer.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.consumer_wait_timeout` | String | `100ms` | The consumer wait timeout.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_init` | String | `500ms` | The initial backoff delay.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_max` | String | `10s` | The maximum backoff delay.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_base` | Integer | `2` | The exponential backoff rate, i.e. next backoff = base * current backoff.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_deadline` | String | `5mins` | The deadline of retries.<br/>**It's only used when the provider is `kafka`**. |
+| `metadata_store` | -- | -- | Metadata storage options. |
+| `metadata_store.file_size` | String | `256MB` | Kv file size in bytes. |
+| `metadata_store.purge_threshold` | String | `4GB` | Kv purge threshold. |
+| `procedure` | -- | -- | Procedure storage options. |
+| `procedure.max_retry_times` | Integer | `3` | Procedure max retry time. |
+| `procedure.retry_delay` | String | `500ms` | Initial retry delay of procedures, increases exponentially |
+| `storage` | -- | -- | The data storage options. |
+| `storage.data_home` | String | `/tmp/greptimedb/` | The working home directory. |
+| `storage.type` | String | `File` | The storage type used to store the data.<br/>- `File`: the data is stored in the local file system.<br/>- `S3`: the data is stored in the S3 object storage.<br/>- `Gcs`: the data is stored in the Google Cloud Storage.<br/>- `Azblob`: the data is stored in the Azure Blob Storage.<br/>- `Oss`: the data is stored in the Aliyun OSS. |
+| `storage.cache_path` | String | `None` | Cache configuration for object storage such as 'S3' etc.<br/>The local file cache directory. |
+| `storage.cache_capacity` | String | `None` | The local file cache capacity in bytes. |
+| `storage.bucket` | String | `None` | The S3 bucket name.<br/>**It's only used when the storage type is `S3`, `Oss` and `Gcs`**. |
+| `storage.root` | String | `None` | The S3 data will be stored in the specified prefix, for example, `s3://${bucket}/${root}`.<br/>**It's only used when the storage type is `S3`, `Oss` and `Azblob`**. |
+| `storage.access_key_id` | String | `None` | The access key id of the aws account.<br/>It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.<br/>**It's only used when the storage type is `S3` and `Oss`**. |
+| `storage.secret_access_key` | String | `None` | The secret access key of the aws account.<br/>It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.<br/>**It's only used when the storage type is `S3`**. |
+| `storage.access_key_secret` | String | `None` | The secret access key of the aliyun account.<br/>**It's only used when the storage type is `Oss`**. |
+| `storage.account_name` | String | `None` | The account key of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.account_key` | String | `None` | The account key of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.scope` | String | `None` | The scope of the google cloud storage.<br/>**It's only used when the storage type is `Gcs`**. |
+| `storage.credential_path` | String | `None` | The credential path of the google cloud storage.<br/>**It's only used when the storage type is `Gcs`**. |
+| `storage.container` | String | `None` | The container of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.sas_token` | String | `None` | The sas token of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.endpoint` | String | `None` | The endpoint of the S3 service.<br/>**It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**. |
+| `storage.region` | String | `None` | The region of the S3 service.<br/>**It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**. |
+| `[[region_engine]]` | -- | -- | The region engine options. You can configure multiple region engines. |
+| `region_engine.mito` | -- | -- | The Mito engine options. |
+| `region_engine.mito.num_workers` | Integer | `8` | Number of region workers. |
+| `region_engine.mito.worker_channel_size` | Integer | `128` | Request channel size of each worker. |
+| `region_engine.mito.worker_request_batch_size` | Integer | `64` | Max batch size for a worker to handle requests. |
+| `region_engine.mito.manifest_checkpoint_distance` | Integer | `10` | Number of meta action updated to trigger a new checkpoint for the manifest. |
+| `region_engine.mito.compress_manifest` | Bool | `false` | Whether to compress manifest and checkpoint file by gzip (default false). |
+| `region_engine.mito.max_background_jobs` | Integer | `4` | Max number of running background jobs |
+| `region_engine.mito.auto_flush_interval` | String | `1h` | Interval to auto flush a region if it has not flushed yet. |
+| `region_engine.mito.global_write_buffer_size` | String | `1GB` | Global write buffer size for all regions. If not set, it's default to 1/8 of OS memory with a max limitation of 1GB. |
+| `region_engine.mito.global_write_buffer_reject_size` | String | `2GB` | Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size` |
+| `region_engine.mito.sst_meta_cache_size` | String | `128MB` | Cache size for SST metadata. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/32 of OS memory with a max limitation of 128MB. |
+| `region_engine.mito.vector_cache_size` | String | `512MB` | Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
+| `region_engine.mito.page_cache_size` | String | `512MB` | Cache size for pages of SST row groups. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
+| `region_engine.mito.sst_write_buffer_size` | String | `8MB` | Buffer size for SST writing. |
+| `region_engine.mito.scan_parallelism` | Integer | `0` | Parallelism to scan a region (default: 1/4 of cpu cores).<br/>- `0`: using the default value (1/4 of cpu cores).<br/>- `1`: scan in current thread.<br/>- `n`: scan in parallelism n. |
+| `region_engine.mito.parallel_scan_channel_size` | Integer | `32` | Capacity of the channel to send data from parallel scan tasks to the main task. |
+| `region_engine.mito.allow_stale_entries` | Bool | `false` | Whether to allow stale WAL entries read during replay. |
+| `region_engine.mito.inverted_index` | -- | -- | The options for inverted index in Mito engine. |
+| `region_engine.mito.inverted_index.create_on_flush` | String | `auto` | Whether to create the index on flush.<br/>- `auto`: automatically<br/>- `disable`: never |
+| `region_engine.mito.inverted_index.create_on_compaction` | String | `auto` | Whether to create the index on compaction.<br/>- `auto`: automatically<br/>- `disable`: never |
+| `region_engine.mito.inverted_index.apply_on_query` | String | `auto` | Whether to apply the index on query<br/>- `auto`: automatically<br/>- `disable`: never |
+| `region_engine.mito.inverted_index.mem_threshold_on_create` | String | `64M` | Memory threshold for performing an external sort during index creation.<br/>Setting to empty will disable external sorting, forcing all sorting operations to happen in memory. |
+| `region_engine.mito.inverted_index.intermediate_path` | String | `""` | File system path to store intermediate files for external sorting (default `{data_home}/index_intermediate`). |
+| `region_engine.mito.memtable` | -- | -- | -- |
+| `region_engine.mito.memtable.type` | String | `partition_tree` | Memtable type.<br/>- `partition_tree`: partition tree memtable<br/>- `time_series`: time-series memtable (deprecated) |
+| `region_engine.mito.memtable.index_max_keys_per_shard` | Integer | `8192` | The max number of keys in one shard. |
+| `region_engine.mito.memtable.data_freeze_threshold` | Integer | `32768` | The max rows of data inside the actively writing buffer in one shard. |
+| `region_engine.mito.memtable.fork_dictionary_bytes` | String | `1GiB` | Max dictionary bytes. |
+| `logging` | -- | -- | The logging options. |
+| `logging.dir` | String | `/tmp/greptimedb/logs` | The directory to store the log files. |
+| `logging.level` | String | `None` | The log level. Can be `info`/`debug`/`warn`/`error`. |
+| `logging.enable_otlp_tracing` | Bool | `false` | Enable OTLP tracing. |
+| `logging.otlp_endpoint` | String | `None` | The OTLP tracing endpoint. |
+| `logging.append_stdout` | Bool | `true` | Whether to append logs to stdout. |
+| `logging.tracing_sample_ratio` | -- | -- | The percentage of tracing will be sampled and exported.<br/>Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.<br/>ratio > 1 are treated as 1. Fractions < 0 are treated as 0 |
+| `logging.tracing_sample_ratio.default_ratio` | Float | `1.0` | -- |
+| `export_metrics` | -- | -- | The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.<br/>This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape. |
+| `export_metrics.enable` | Bool | `false` | whether enable export metrics. |
+| `export_metrics.write_interval` | String | `30s` | The interval of export metrics. |
+| `export_metrics.self_import` | -- | -- | For `standalone` mode, `self_import` is recommend to collect metrics generated by itself |
+| `export_metrics.self_import.db` | String | `None` | -- |
+| `export_metrics.remote_write` | -- | -- | -- |
+| `export_metrics.remote_write.url` | String | `""` | The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`. |
+| `export_metrics.remote_write.headers` | InlineTable | -- | HTTP headers of Prometheus remote-write carry. |
+
+
+## Cluster Mode
+
+### Frontend
+
+| Key | Type | Default | Descriptions |
+| --- | -----| ------- | ----------- |
+| `mode` | String | `standalone` | The running mode of the datanode. It can be `standalone` or `distributed`. |
+| `default_timezone` | String | `None` | The default timezone of the server. |
+| `heartbeat` | -- | -- | The heartbeat options. |
+| `heartbeat.interval` | String | `18s` | Interval for sending heartbeat messages to the metasrv. |
+| `heartbeat.retry_interval` | String | `3s` | Interval for retrying to send heartbeat messages to the metasrv. |
+| `http` | -- | -- | The HTTP server options. |
+| `http.addr` | String | `127.0.0.1:4000` | The address to bind the HTTP server. |
+| `http.timeout` | String | `30s` | HTTP request timeout. |
+| `http.body_limit` | String | `64MB` | HTTP request body limit.<br/>Support the following units are supported: `B`, `KB`, `KiB`, `MB`, `MiB`, `GB`, `GiB`, `TB`, `TiB`, `PB`, `PiB`. |
+| `grpc` | -- | -- | The gRPC server options. |
+| `grpc.addr` | String | `127.0.0.1:4001` | The address to bind the gRPC server. |
+| `grpc.runtime_size` | Integer | `8` | The number of server worker threads. |
+| `mysql` | -- | -- | MySQL server options. |
+| `mysql.enable` | Bool | `true` | Whether to enable. |
+| `mysql.addr` | String | `127.0.0.1:4002` | The addr to bind the MySQL server. |
+| `mysql.runtime_size` | Integer | `2` | The number of server worker threads. |
+| `mysql.tls` | -- | -- | -- |
+| `mysql.tls.mode` | String | `disable` | TLS mode, refer to https://www.postgresql.org/docs/current/libpq-ssl.html<br/>- `disable` (default value)<br/>- `prefer`<br/>- `require`<br/>- `verify-ca`<br/>- `verify-full` |
+| `mysql.tls.cert_path` | String | `None` | Certificate file path. |
+| `mysql.tls.key_path` | String | `None` | Private key file path. |
+| `mysql.tls.watch` | Bool | `false` | Watch for Certificate and key file change and auto reload |
+| `postgres` | -- | -- | PostgresSQL server options. |
+| `postgres.enable` | Bool | `true` | Whether to enable |
+| `postgres.addr` | String | `127.0.0.1:4003` | The addr to bind the PostgresSQL server. |
+| `postgres.runtime_size` | Integer | `2` | The number of server worker threads. |
+| `postgres.tls` | -- | -- | PostgresSQL server TLS options, see `mysql_options.tls` section. |
+| `postgres.tls.mode` | String | `disable` | TLS mode. |
+| `postgres.tls.cert_path` | String | `None` | Certificate file path. |
+| `postgres.tls.key_path` | String | `None` | Private key file path. |
+| `postgres.tls.watch` | Bool | `false` | Watch for Certificate and key file change and auto reload |
+| `opentsdb` | -- | -- | OpenTSDB protocol options. |
+| `opentsdb.enable` | Bool | `true` | Whether to enable |
+| `opentsdb.addr` | String | `127.0.0.1:4242` | OpenTSDB telnet API server address. |
+| `opentsdb.runtime_size` | Integer | `2` | The number of server worker threads. |
+| `influxdb` | -- | -- | InfluxDB protocol options. |
+| `influxdb.enable` | Bool | `true` | Whether to enable InfluxDB protocol in HTTP API. |
+| `prom_store` | -- | -- | Prometheus remote storage options |
+| `prom_store.enable` | Bool | `true` | Whether to enable Prometheus remote write and read in HTTP API. |
+| `prom_store.with_metric_engine` | Bool | `true` | Whether to store the data from Prometheus remote write in metric engine. |
+| `meta_client` | -- | -- | The metasrv client options. |
+| `meta_client.metasrv_addrs` | Array | -- | The addresses of the metasrv. |
+| `meta_client.timeout` | String | `3s` | Operation timeout. |
+| `meta_client.heartbeat_timeout` | String | `500ms` | Heartbeat timeout. |
+| `meta_client.ddl_timeout` | String | `10s` | DDL timeout. |
+| `meta_client.connect_timeout` | String | `1s` | Connect server timeout. |
+| `meta_client.tcp_nodelay` | Bool | `true` | `TCP_NODELAY` option for accepted connections. |
+| `meta_client.metadata_cache_max_capacity` | Integer | `100000` | The configuration about the cache of the metadata. |
+| `meta_client.metadata_cache_ttl` | String | `10m` | TTL of the metadata cache. |
+| `meta_client.metadata_cache_tti` | String | `5m` | -- |
+| `datanode` | -- | -- | Datanode options. |
+| `datanode.client` | -- | -- | Datanode client options. |
+| `datanode.client.timeout` | String | `10s` | -- |
+| `datanode.client.connect_timeout` | String | `10s` | -- |
+| `datanode.client.tcp_nodelay` | Bool | `true` | -- |
+| `logging` | -- | -- | The logging options. |
+| `logging.dir` | String | `/tmp/greptimedb/logs` | The directory to store the log files. |
+| `logging.level` | String | `None` | The log level. Can be `info`/`debug`/`warn`/`error`. |
+| `logging.enable_otlp_tracing` | Bool | `false` | Enable OTLP tracing. |
+| `logging.otlp_endpoint` | String | `None` | The OTLP tracing endpoint. |
+| `logging.append_stdout` | Bool | `true` | Whether to append logs to stdout. |
+| `logging.tracing_sample_ratio` | -- | -- | The percentage of tracing will be sampled and exported.<br/>Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.<br/>ratio > 1 are treated as 1. Fractions < 0 are treated as 0 |
+| `logging.tracing_sample_ratio.default_ratio` | Float | `1.0` | -- |
+| `export_metrics` | -- | -- | The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.<br/>This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape. |
+| `export_metrics.enable` | Bool | `false` | whether enable export metrics. |
+| `export_metrics.write_interval` | String | `30s` | The interval of export metrics. |
+| `export_metrics.self_import` | -- | -- | For `standalone` mode, `self_import` is recommend to collect metrics generated by itself |
+| `export_metrics.self_import.db` | String | `None` | -- |
+| `export_metrics.remote_write` | -- | -- | -- |
+| `export_metrics.remote_write.url` | String | `""` | The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`. |
+| `export_metrics.remote_write.headers` | InlineTable | -- | HTTP headers of Prometheus remote-write carry. |
+
+
+### Metasrv
+
+| Key | Type | Default | Descriptions |
+| --- | -----| ------- | ----------- |
+| `data_home` | String | `/tmp/metasrv/` | The working home directory. |
+| `bind_addr` | String | `127.0.0.1:3002` | The bind address of metasrv. |
+| `server_addr` | String | `127.0.0.1:3002` | The communication server address for frontend and datanode to connect to metasrv,  "127.0.0.1:3002" by default for localhost. |
+| `store_addr` | String | `127.0.0.1:2379` | Etcd server address. |
+| `selector` | String | `lease_based` | Datanode selector type.<br/>- `lease_based` (default value).<br/>- `load_based`<br/>For details, please see "https://docs.greptime.com/developer-guide/metasrv/selector". |
+| `use_memory_store` | Bool | `false` | Store data in memory. |
+| `enable_telemetry` | Bool | `true` | Whether to enable greptimedb telemetry. |
+| `store_key_prefix` | String | `""` | If it's not empty, the metasrv will store all data with this key prefix. |
+| `procedure` | -- | -- | Procedure storage options. |
+| `procedure.max_retry_times` | Integer | `12` | Procedure max retry time. |
+| `procedure.retry_delay` | String | `500ms` | Initial retry delay of procedures, increases exponentially |
+| `procedure.max_metadata_value_size` | String | `1500KiB` | Auto split large value<br/>GreptimeDB procedure uses etcd as the default metadata storage backend.<br/>The etcd the maximum size of any request is 1.5 MiB<br/>1500KiB = 1536KiB (1.5MiB) - 36KiB (reserved size of key)<br/>Comments out the `max_metadata_value_size`, for don't split large value (no limit). |
+| `failure_detector` | -- | -- | -- |
+| `failure_detector.threshold` | Float | `8.0` | -- |
+| `failure_detector.min_std_deviation` | String | `100ms` | -- |
+| `failure_detector.acceptable_heartbeat_pause` | String | `3000ms` | -- |
+| `failure_detector.first_heartbeat_estimate` | String | `1000ms` | -- |
+| `datanode` | -- | -- | Datanode options. |
+| `datanode.client` | -- | -- | Datanode client options. |
+| `datanode.client.timeout` | String | `10s` | -- |
+| `datanode.client.connect_timeout` | String | `10s` | -- |
+| `datanode.client.tcp_nodelay` | Bool | `true` | -- |
+| `wal` | -- | -- | -- |
+| `wal.provider` | String | `raft_engine` | -- |
+| `wal.broker_endpoints` | Array | -- | The broker endpoints of the Kafka cluster. |
+| `wal.num_topics` | Integer | `64` | Number of topics to be created upon start. |
+| `wal.selector_type` | String | `round_robin` | Topic selector type.<br/>Available selector types:<br/>- `round_robin` (default) |
+| `wal.topic_name_prefix` | String | `greptimedb_wal_topic` | A Kafka topic is constructed by concatenating `topic_name_prefix` and `topic_id`. |
+| `wal.replication_factor` | Integer | `1` | Expected number of replicas of each partition. |
+| `wal.create_topic_timeout` | String | `30s` | Above which a topic creation operation will be cancelled. |
+| `wal.backoff_init` | String | `500ms` | The initial backoff for kafka clients. |
+| `wal.backoff_max` | String | `10s` | The maximum backoff for kafka clients. |
+| `wal.backoff_base` | Integer | `2` | Exponential backoff rate, i.e. next backoff = base * current backoff. |
+| `wal.backoff_deadline` | String | `5mins` | Stop reconnecting if the total wait time reaches the deadline. If this config is missing, the reconnecting won't terminate. |
+| `logging` | -- | -- | The logging options. |
+| `logging.dir` | String | `/tmp/greptimedb/logs` | The directory to store the log files. |
+| `logging.level` | String | `None` | The log level. Can be `info`/`debug`/`warn`/`error`. |
+| `logging.enable_otlp_tracing` | Bool | `false` | Enable OTLP tracing. |
+| `logging.otlp_endpoint` | String | `None` | The OTLP tracing endpoint. |
+| `logging.append_stdout` | Bool | `true` | Whether to append logs to stdout. |
+| `logging.tracing_sample_ratio` | -- | -- | The percentage of tracing will be sampled and exported.<br/>Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.<br/>ratio > 1 are treated as 1. Fractions < 0 are treated as 0 |
+| `logging.tracing_sample_ratio.default_ratio` | Float | `1.0` | -- |
+| `export_metrics` | -- | -- | The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.<br/>This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape. |
+| `export_metrics.enable` | Bool | `false` | whether enable export metrics. |
+| `export_metrics.write_interval` | String | `30s` | The interval of export metrics. |
+| `export_metrics.self_import` | -- | -- | For `standalone` mode, `self_import` is recommend to collect metrics generated by itself |
+| `export_metrics.self_import.db` | String | `None` | -- |
+| `export_metrics.remote_write` | -- | -- | -- |
+| `export_metrics.remote_write.url` | String | `""` | The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`. |
+| `export_metrics.remote_write.headers` | InlineTable | -- | HTTP headers of Prometheus remote-write carry. |
+
+
+### Datanode
+
+| Key | Type | Default | Descriptions |
+| --- | -----| ------- | ----------- |
+| `mode` | String | `standalone` | The running mode of the datanode. It can be `standalone` or `distributed`. |
+| `node_id` | Integer | `None` | The datanode identifier and should be unique in the cluster. |
+| `require_lease_before_startup` | Bool | `false` | Start services after regions have obtained leases.<br/>It will block the datanode start if it can't receive leases in the heartbeat from metasrv. |
+| `init_regions_in_background` | Bool | `false` | Initialize all regions in the background during the startup.<br/>By default, it provides services after all regions have been initialized. |
+| `rpc_addr` | String | `127.0.0.1:3001` | The gRPC address of the datanode. |
+| `rpc_hostname` | String | `None` | The hostname of the datanode. |
+| `rpc_runtime_size` | Integer | `8` | The number of gRPC server worker threads. |
+| `rpc_max_recv_message_size` | String | `512MB` | The maximum receive message size for gRPC server. |
+| `rpc_max_send_message_size` | String | `512MB` | The maximum send message size for gRPC server. |
+| `enable_telemetry` | Bool | `true` | Enable telemetry to collect anonymous usage data. |
+| `heartbeat` | -- | -- | The heartbeat options. |
+| `heartbeat.interval` | String | `3s` | Interval for sending heartbeat messages to the metasrv. |
+| `heartbeat.retry_interval` | String | `3s` | Interval for retrying to send heartbeat messages to the metasrv. |
+| `meta_client` | -- | -- | The metasrv client options. |
+| `meta_client.metasrv_addrs` | Array | -- | The addresses of the metasrv. |
+| `meta_client.timeout` | String | `3s` | Operation timeout. |
+| `meta_client.heartbeat_timeout` | String | `500ms` | Heartbeat timeout. |
+| `meta_client.ddl_timeout` | String | `10s` | DDL timeout. |
+| `meta_client.connect_timeout` | String | `1s` | Connect server timeout. |
+| `meta_client.tcp_nodelay` | Bool | `true` | `TCP_NODELAY` option for accepted connections. |
+| `meta_client.metadata_cache_max_capacity` | Integer | `100000` | The configuration about the cache of the metadata. |
+| `meta_client.metadata_cache_ttl` | String | `10m` | TTL of the metadata cache. |
+| `meta_client.metadata_cache_tti` | String | `5m` | -- |
+| `wal` | -- | -- | The WAL options. |
+| `wal.provider` | String | `raft_engine` | The provider of the WAL.<br/>- `raft_engine`: the wal is stored in the local file system by raft-engine.<br/>- `kafka`: it's remote wal that data is stored in Kafka. |
+| `wal.dir` | String | `None` | The directory to store the WAL files.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.file_size` | String | `256MB` | The size of the WAL segment file.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.purge_threshold` | String | `4GB` | The threshold of the WAL size to trigger a flush.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.purge_interval` | String | `10m` | The interval to trigger a flush.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.read_batch_size` | Integer | `128` | The read batch size.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.sync_write` | Bool | `false` | Whether to use sync write.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.enable_log_recycle` | Bool | `true` | Whether to reuse logically truncated log files.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.prefill_log_files` | Bool | `false` | Whether to pre-create log files on start up.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.sync_period` | String | `10s` | Duration for fsyncing log files.<br/>**It's only used when the provider is `raft_engine`**. |
+| `wal.broker_endpoints` | Array | -- | The Kafka broker endpoints.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.max_batch_size` | String | `1MB` | The max size of a single producer batch.<br/>Warning: Kafka has a default limit of 1MB per message in a topic.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.linger` | String | `200ms` | The linger duration of a kafka batch producer.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.consumer_wait_timeout` | String | `100ms` | The consumer wait timeout.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_init` | String | `500ms` | The initial backoff delay.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_max` | String | `10s` | The maximum backoff delay.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_base` | Integer | `2` | The exponential backoff rate, i.e. next backoff = base * current backoff.<br/>**It's only used when the provider is `kafka`**. |
+| `wal.backoff_deadline` | String | `5mins` | The deadline of retries.<br/>**It's only used when the provider is `kafka`**. |
+| `storage` | -- | -- | The data storage options. |
+| `storage.data_home` | String | `/tmp/greptimedb/` | The working home directory. |
+| `storage.type` | String | `File` | The storage type used to store the data.<br/>- `File`: the data is stored in the local file system.<br/>- `S3`: the data is stored in the S3 object storage.<br/>- `Gcs`: the data is stored in the Google Cloud Storage.<br/>- `Azblob`: the data is stored in the Azure Blob Storage.<br/>- `Oss`: the data is stored in the Aliyun OSS. |
+| `storage.cache_path` | String | `None` | Cache configuration for object storage such as 'S3' etc.<br/>The local file cache directory. |
+| `storage.cache_capacity` | String | `None` | The local file cache capacity in bytes. |
+| `storage.bucket` | String | `None` | The S3 bucket name.<br/>**It's only used when the storage type is `S3`, `Oss` and `Gcs`**. |
+| `storage.root` | String | `None` | The S3 data will be stored in the specified prefix, for example, `s3://${bucket}/${root}`.<br/>**It's only used when the storage type is `S3`, `Oss` and `Azblob`**. |
+| `storage.access_key_id` | String | `None` | The access key id of the aws account.<br/>It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.<br/>**It's only used when the storage type is `S3` and `Oss`**. |
+| `storage.secret_access_key` | String | `None` | The secret access key of the aws account.<br/>It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.<br/>**It's only used when the storage type is `S3`**. |
+| `storage.access_key_secret` | String | `None` | The secret access key of the aliyun account.<br/>**It's only used when the storage type is `Oss`**. |
+| `storage.account_name` | String | `None` | The account key of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.account_key` | String | `None` | The account key of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.scope` | String | `None` | The scope of the google cloud storage.<br/>**It's only used when the storage type is `Gcs`**. |
+| `storage.credential_path` | String | `None` | The credential path of the google cloud storage.<br/>**It's only used when the storage type is `Gcs`**. |
+| `storage.container` | String | `None` | The container of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.sas_token` | String | `None` | The sas token of the azure account.<br/>**It's only used when the storage type is `Azblob`**. |
+| `storage.endpoint` | String | `None` | The endpoint of the S3 service.<br/>**It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**. |
+| `storage.region` | String | `None` | The region of the S3 service.<br/>**It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**. |
+| `[[region_engine]]` | -- | -- | The region engine options. You can configure multiple region engines. |
+| `region_engine.mito` | -- | -- | The Mito engine options. |
+| `region_engine.mito.num_workers` | Integer | `8` | Number of region workers. |
+| `region_engine.mito.worker_channel_size` | Integer | `128` | Request channel size of each worker. |
+| `region_engine.mito.worker_request_batch_size` | Integer | `64` | Max batch size for a worker to handle requests. |
+| `region_engine.mito.manifest_checkpoint_distance` | Integer | `10` | Number of meta action updated to trigger a new checkpoint for the manifest. |
+| `region_engine.mito.compress_manifest` | Bool | `false` | Whether to compress manifest and checkpoint file by gzip (default false). |
+| `region_engine.mito.max_background_jobs` | Integer | `4` | Max number of running background jobs |
+| `region_engine.mito.auto_flush_interval` | String | `1h` | Interval to auto flush a region if it has not flushed yet. |
+| `region_engine.mito.global_write_buffer_size` | String | `1GB` | Global write buffer size for all regions. If not set, it's default to 1/8 of OS memory with a max limitation of 1GB. |
+| `region_engine.mito.global_write_buffer_reject_size` | String | `2GB` | Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size` |
+| `region_engine.mito.sst_meta_cache_size` | String | `128MB` | Cache size for SST metadata. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/32 of OS memory with a max limitation of 128MB. |
+| `region_engine.mito.vector_cache_size` | String | `512MB` | Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
+| `region_engine.mito.page_cache_size` | String | `512MB` | Cache size for pages of SST row groups. Setting it to 0 to disable the cache.<br/>If not set, it's default to 1/16 of OS memory with a max limitation of 512MB. |
+| `region_engine.mito.sst_write_buffer_size` | String | `8MB` | Buffer size for SST writing. |
+| `region_engine.mito.scan_parallelism` | Integer | `0` | Parallelism to scan a region (default: 1/4 of cpu cores).<br/>- `0`: using the default value (1/4 of cpu cores).<br/>- `1`: scan in current thread.<br/>- `n`: scan in parallelism n. |
+| `region_engine.mito.parallel_scan_channel_size` | Integer | `32` | Capacity of the channel to send data from parallel scan tasks to the main task. |
+| `region_engine.mito.allow_stale_entries` | Bool | `false` | Whether to allow stale WAL entries read during replay. |
+| `region_engine.mito.inverted_index` | -- | -- | The options for inverted index in Mito engine. |
+| `region_engine.mito.inverted_index.create_on_flush` | String | `auto` | Whether to create the index on flush.<br/>- `auto`: automatically<br/>- `disable`: never |
+| `region_engine.mito.inverted_index.create_on_compaction` | String | `auto` | Whether to create the index on compaction.<br/>- `auto`: automatically<br/>- `disable`: never |
+| `region_engine.mito.inverted_index.apply_on_query` | String | `auto` | Whether to apply the index on query<br/>- `auto`: automatically<br/>- `disable`: never |
+| `region_engine.mito.inverted_index.mem_threshold_on_create` | String | `64M` | Memory threshold for performing an external sort during index creation.<br/>Setting to empty will disable external sorting, forcing all sorting operations to happen in memory. |
+| `region_engine.mito.inverted_index.intermediate_path` | String | `""` | File system path to store intermediate files for external sorting (default `{data_home}/index_intermediate`). |
+| `region_engine.mito.memtable` | -- | -- | -- |
+| `region_engine.mito.memtable.type` | String | `partition_tree` | Memtable type.<br/>- `partition_tree`: partition tree memtable<br/>- `time_series`: time-series memtable (deprecated) |
+| `region_engine.mito.memtable.index_max_keys_per_shard` | Integer | `8192` | The max number of keys in one shard. |
+| `region_engine.mito.memtable.data_freeze_threshold` | Integer | `32768` | The max rows of data inside the actively writing buffer in one shard. |
+| `region_engine.mito.memtable.fork_dictionary_bytes` | String | `1GiB` | Max dictionary bytes. |
+| `logging` | -- | -- | The logging options. |
+| `logging.dir` | String | `/tmp/greptimedb/logs` | The directory to store the log files. |
+| `logging.level` | String | `None` | The log level. Can be `info`/`debug`/`warn`/`error`. |
+| `logging.enable_otlp_tracing` | Bool | `false` | Enable OTLP tracing. |
+| `logging.otlp_endpoint` | String | `None` | The OTLP tracing endpoint. |
+| `logging.append_stdout` | Bool | `true` | Whether to append logs to stdout. |
+| `logging.tracing_sample_ratio` | -- | -- | The percentage of tracing will be sampled and exported.<br/>Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.<br/>ratio > 1 are treated as 1. Fractions < 0 are treated as 0 |
+| `logging.tracing_sample_ratio.default_ratio` | Float | `1.0` | -- |
+| `export_metrics` | -- | -- | The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.<br/>This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape. |
+| `export_metrics.enable` | Bool | `false` | whether enable export metrics. |
+| `export_metrics.write_interval` | String | `30s` | The interval of export metrics. |
+| `export_metrics.self_import` | -- | -- | For `standalone` mode, `self_import` is recommend to collect metrics generated by itself |
+| `export_metrics.self_import.db` | String | `None` | -- |
+| `export_metrics.remote_write` | -- | -- | -- |
+| `export_metrics.remote_write.url` | String | `""` | The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`. |
+| `export_metrics.remote_write.headers` | InlineTable | -- | HTTP headers of Prometheus remote-write carry. |
diff --git a/config/datanode.example.toml b/config/datanode.example.toml
index 6d80fd839f..498b728241 100644
--- a/config/datanode.example.toml
+++ b/config/datanode.example.toml
@@ -1,169 +1,427 @@
-# Node running mode, see `standalone.example.toml`.
-mode = "distributed"
-# The datanode identifier, should be unique.
+## The running mode of the datanode. It can be `standalone` or `distributed`.
+mode = "standalone"
+
+## The datanode identifier and should be unique in the cluster.
+## +toml2docs:none-default
 node_id = 42
-# gRPC server address, "127.0.0.1:3001" by default.
-rpc_addr = "127.0.0.1:3001"
-# Hostname of this node.
-rpc_hostname = "127.0.0.1"
-# The number of gRPC server worker threads, 8 by default.
-rpc_runtime_size = 8
-# Start services after regions have obtained leases.
-# It will block the datanode start if it can't receive leases in the heartbeat from metasrv.
+
+## Start services after regions have obtained leases.
+## It will block the datanode start if it can't receive leases in the heartbeat from metasrv.
 require_lease_before_startup = false
 
-# Initialize all regions in the background during the startup.
-# By default, it provides services after all regions have been initialized.
+## Initialize all regions in the background during the startup.
+## By default, it provides services after all regions have been initialized.
 init_regions_in_background = false
 
+## The gRPC address of the datanode.
+rpc_addr = "127.0.0.1:3001"
+
+## The hostname of the datanode.
+## +toml2docs:none-default
+rpc_hostname = "127.0.0.1"
+
+## The number of gRPC server worker threads.
+rpc_runtime_size = 8
+
+## The maximum receive message size for gRPC server.
+rpc_max_recv_message_size = "512MB"
+
+## The maximum send message size for gRPC server.
+rpc_max_send_message_size = "512MB"
+
+## Enable telemetry to collect anonymous usage data.
+enable_telemetry = true
+
+## The heartbeat options.
 [heartbeat]
-# Interval for sending heartbeat messages to the Metasrv, 3 seconds by default.
+## Interval for sending heartbeat messages to the metasrv.
 interval = "3s"
 
-# Metasrv client options.
+## Interval for retrying to send heartbeat messages to the metasrv.
+retry_interval = "3s"
+
+## The metasrv client options.
 [meta_client]
-# Metasrv address list.
+## The addresses of the metasrv.
 metasrv_addrs = ["127.0.0.1:3002"]
-# Heartbeat timeout, 500 milliseconds by default.
-heartbeat_timeout = "500ms"
-# Operation timeout, 3 seconds by default.
+
+## Operation timeout.
 timeout = "3s"
-# Connect server timeout, 1 second by default.
+
+## Heartbeat timeout.
+heartbeat_timeout = "500ms"
+
+## DDL timeout.
+ddl_timeout = "10s"
+
+## Connect server timeout.
 connect_timeout = "1s"
-# `TCP_NODELAY` option for accepted connections, true by default.
+
+## `TCP_NODELAY` option for accepted connections.
 tcp_nodelay = true
 
-# WAL options.
+## The configuration about the cache of the metadata.
+metadata_cache_max_capacity = 100000
+
+## TTL of the metadata cache.
+metadata_cache_ttl = "10m"
+
+# TTI of the metadata cache.
+metadata_cache_tti = "5m"
+
+## The WAL options.
 [wal]
+## The provider of the WAL.
+## - `raft_engine`: the wal is stored in the local file system by raft-engine.
+## - `kafka`: it's remote wal that data is stored in Kafka.
 provider = "raft_engine"
 
-# Raft-engine wal options, see `standalone.example.toml`.
-# dir = "/tmp/greptimedb/wal"
+## The directory to store the WAL files.
+## **It's only used when the provider is `raft_engine`**.
+## +toml2docs:none-default
+dir = "/tmp/greptimedb/wal"
+
+## The size of the WAL segment file.
+## **It's only used when the provider is `raft_engine`**.
 file_size = "256MB"
+
+## The threshold of the WAL size to trigger a flush.
+## **It's only used when the provider is `raft_engine`**.
 purge_threshold = "4GB"
+
+## The interval to trigger a flush.
+## **It's only used when the provider is `raft_engine`**.
 purge_interval = "10m"
+
+## The read batch size.
+## **It's only used when the provider is `raft_engine`**.
 read_batch_size = 128
+
+## Whether to use sync write.
+## **It's only used when the provider is `raft_engine`**.
 sync_write = false
 
-# Kafka wal options, see `standalone.example.toml`.
-# broker_endpoints = ["127.0.0.1:9092"]
-# Warning: Kafka has a default limit of 1MB per message in a topic.
-# max_batch_size = "1MB"
-# linger = "200ms"
-# consumer_wait_timeout = "100ms"
-# backoff_init = "500ms"
-# backoff_max = "10s"
-# backoff_base = 2
-# backoff_deadline = "5mins"
+## Whether to reuse logically truncated log files.
+## **It's only used when the provider is `raft_engine`**.
+enable_log_recycle = true
 
-# Storage options, see `standalone.example.toml`.
+## Whether to pre-create log files on start up.
+## **It's only used when the provider is `raft_engine`**.
+prefill_log_files = false
+
+## Duration for fsyncing log files.
+## **It's only used when the provider is `raft_engine`**.
+sync_period = "10s"
+
+## The Kafka broker endpoints.
+## **It's only used when the provider is `kafka`**.
+broker_endpoints = ["127.0.0.1:9092"]
+
+## The max size of a single producer batch.
+## Warning: Kafka has a default limit of 1MB per message in a topic.
+## **It's only used when the provider is `kafka`**.
+max_batch_size = "1MB"
+
+## The linger duration of a kafka batch producer.
+## **It's only used when the provider is `kafka`**.
+linger = "200ms"
+
+## The consumer wait timeout.
+## **It's only used when the provider is `kafka`**.
+consumer_wait_timeout = "100ms"
+
+## The initial backoff delay.
+## **It's only used when the provider is `kafka`**.
+backoff_init = "500ms"
+
+## The maximum backoff delay.
+## **It's only used when the provider is `kafka`**.
+backoff_max = "10s"
+
+## The exponential backoff rate, i.e. next backoff = base * current backoff.
+## **It's only used when the provider is `kafka`**.
+backoff_base = 2
+
+## The deadline of retries.
+## **It's only used when the provider is `kafka`**.
+backoff_deadline = "5mins"
+
+# Example of using S3 as the storage.
+# [storage]
+# type = "S3"
+# bucket = "greptimedb"
+# root = "data"
+# access_key_id = "test"
+# secret_access_key = "123456"
+# endpoint = "https://s3.amazonaws.com"
+# region = "us-west-2"
+
+# Example of using Oss as the storage.
+# [storage]
+# type = "Oss"
+# bucket = "greptimedb"
+# root = "data"
+# access_key_id = "test"
+# access_key_secret = "123456"
+# endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
+
+# Example of using Azblob as the storage.
+# [storage]
+# type = "Azblob"
+# container = "greptimedb"
+# root = "data"
+# account_name = "test"
+# account_key = "123456"
+# endpoint = "https://greptimedb.blob.core.windows.net"
+# sas_token = ""
+
+# Example of using Gcs as the storage.
+# [storage]
+# type = "Gcs"
+# bucket = "greptimedb"
+# root = "data"
+# scope = "test"
+# credential_path = "123456"
+# endpoint = "https://storage.googleapis.com"
+
+## The data storage options.
 [storage]
-# The working home directory.
+## The working home directory.
 data_home = "/tmp/greptimedb/"
-# Storage type.
+
+## The storage type used to store the data.
+## - `File`: the data is stored in the local file system.
+## - `S3`: the data is stored in the S3 object storage.
+## - `Gcs`: the data is stored in the Google Cloud Storage.
+## - `Azblob`: the data is stored in the Azure Blob Storage.
+## - `Oss`: the data is stored in the Aliyun OSS.
 type = "File"
 
-# Cache configuration for object storage such as 'S3' etc.
-# The local file cache directory
-# cache_path = "/path/local_cache"
-# The local file cache capacity in bytes.
-# cache_capacity = "256MB"
+## Cache configuration for object storage such as 'S3' etc.
+## The local file cache directory.
+## +toml2docs:none-default
+cache_path = "/path/local_cache"
+
+## The local file cache capacity in bytes.
+## +toml2docs:none-default
+cache_capacity = "256MB"
+
+## The S3 bucket name.
+## **It's only used when the storage type is `S3`, `Oss` and `Gcs`**.
+## +toml2docs:none-default
+bucket = "greptimedb"
+
+## The S3 data will be stored in the specified prefix, for example, `s3://${bucket}/${root}`.
+## **It's only used when the storage type is `S3`, `Oss` and `Azblob`**.
+## +toml2docs:none-default
+root = "greptimedb"
+
+## The access key id of the aws account.
+## It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.
+## **It's only used when the storage type is `S3` and `Oss`**.
+## +toml2docs:none-default
+access_key_id = "test"
+
+## The secret access key of the aws account.
+## It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.
+## **It's only used when the storage type is `S3`**.
+## +toml2docs:none-default
+secret_access_key = "test"
+
+## The secret access key of the aliyun account.
+## **It's only used when the storage type is `Oss`**.
+## +toml2docs:none-default
+access_key_secret = "test"
+
+## The account key of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+account_name = "test"
+
+## The account key of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+account_key = "test"
+
+## The scope of the google cloud storage.
+## **It's only used when the storage type is `Gcs`**.
+## +toml2docs:none-default
+scope = "test"
+
+## The credential path of the google cloud storage.
+## **It's only used when the storage type is `Gcs`**.
+## +toml2docs:none-default
+credential_path = "test"
+
+## The container of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+container = "greptimedb"
+
+## The sas token of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+sas_token = ""
+
+## The endpoint of the S3 service.
+## **It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**.
+## +toml2docs:none-default
+endpoint = "https://s3.amazonaws.com"
+
+## The region of the S3 service.
+## **It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**.
+## +toml2docs:none-default
+region = "us-west-2"
 
 # Custom storage options
-#[[storage.providers]]
-#type = "S3"
-#[[storage.providers]]
-#type = "Gcs"
+# [[storage.providers]]
+# type = "S3"
+# [[storage.providers]]
+# type = "Gcs"
 
-# Mito engine options
+## The region engine options. You can configure multiple region engines.
 [[region_engine]]
+
+## The Mito engine options.
 [region_engine.mito]
-# Number of region workers
+
+## Number of region workers.
 num_workers = 8
-# Request channel size of each worker
+
+## Request channel size of each worker.
 worker_channel_size = 128
-# Max batch size for a worker to handle requests
+
+## Max batch size for a worker to handle requests.
 worker_request_batch_size = 64
-# Number of meta action updated to trigger a new checkpoint for the manifest
+
+## Number of meta action updated to trigger a new checkpoint for the manifest.
 manifest_checkpoint_distance = 10
-# Whether to compress manifest and checkpoint file by gzip (default false).
+
+## Whether to compress manifest and checkpoint file by gzip (default false).
 compress_manifest = false
-# Max number of running background jobs
+
+## Max number of running background jobs
 max_background_jobs = 4
-# Interval to auto flush a region if it has not flushed yet.
+
+## Interval to auto flush a region if it has not flushed yet.
 auto_flush_interval = "1h"
-# Global write buffer size for all regions. If not set, it's default to 1/8 of OS memory with a max limitation of 1GB.
+
+## Global write buffer size for all regions. If not set, it's default to 1/8 of OS memory with a max limitation of 1GB.
 global_write_buffer_size = "1GB"
-# Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size`
+
+## Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size`
 global_write_buffer_reject_size = "2GB"
-# Cache size for SST metadata. Setting it to 0 to disable the cache.
-# If not set, it's default to 1/32 of OS memory with a max limitation of 128MB.
+
+## Cache size for SST metadata. Setting it to 0 to disable the cache.
+## If not set, it's default to 1/32 of OS memory with a max limitation of 128MB.
 sst_meta_cache_size = "128MB"
-# Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.
-# If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+
+## Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.
+## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
 vector_cache_size = "512MB"
-# Cache size for pages of SST row groups. Setting it to 0 to disable the cache.
-# If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+
+## Cache size for pages of SST row groups. Setting it to 0 to disable the cache.
+## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
 page_cache_size = "512MB"
-# Buffer size for SST writing.
+
+## Buffer size for SST writing.
 sst_write_buffer_size = "8MB"
-# Parallelism to scan a region (default: 1/4 of cpu cores).
-# - 0: using the default value (1/4 of cpu cores).
-# - 1: scan in current thread.
-# - n: scan in parallelism n.
+
+## Parallelism to scan a region (default: 1/4 of cpu cores).
+## - `0`: using the default value (1/4 of cpu cores).
+## - `1`: scan in current thread.
+## - `n`: scan in parallelism n.
 scan_parallelism = 0
-# Capacity of the channel to send data from parallel scan tasks to the main task (default 32).
+
+## Capacity of the channel to send data from parallel scan tasks to the main task.
 parallel_scan_channel_size = 32
-# Whether to allow stale WAL entries read during replay.
+
+## Whether to allow stale WAL entries read during replay.
 allow_stale_entries = false
 
+## The options for inverted index in Mito engine.
 [region_engine.mito.inverted_index]
-# Whether to create the index on flush.
-# - "auto": automatically
-# - "disable": never
+
+## Whether to create the index on flush.
+## - `auto`: automatically
+## - `disable`: never
 create_on_flush = "auto"
-# Whether to create the index on compaction.
-# - "auto": automatically
-# - "disable": never
+
+## Whether to create the index on compaction.
+## - `auto`: automatically
+## - `disable`: never
 create_on_compaction = "auto"
-# Whether to apply the index on query
-# - "auto": automatically
-# - "disable": never
+
+## Whether to apply the index on query
+## - `auto`: automatically
+## - `disable`: never
 apply_on_query = "auto"
-# Memory threshold for performing an external sort during index creation.
-# Setting to empty will disable external sorting, forcing all sorting operations to happen in memory.
+
+## Memory threshold for performing an external sort during index creation.
+## Setting to empty will disable external sorting, forcing all sorting operations to happen in memory.
 mem_threshold_on_create = "64M"
-# File system path to store intermediate files for external sorting (default `{data_home}/index_intermediate`).
+
+## File system path to store intermediate files for external sorting (default `{data_home}/index_intermediate`).
 intermediate_path = ""
 
 [region_engine.mito.memtable]
-# Memtable type.
-# - "partition_tree": partition tree memtable
-# - "time_series": time-series memtable (deprecated)
+## Memtable type.
+## - `partition_tree`: partition tree memtable
+## - `time_series`: time-series memtable (deprecated)
 type = "partition_tree"
-# The max number of keys in one shard.
+
+## The max number of keys in one shard.
 index_max_keys_per_shard = 8192
-# The max rows of data inside the actively writing buffer in one shard.
+
+## The max rows of data inside the actively writing buffer in one shard.
 data_freeze_threshold = 32768
-# Max dictionary bytes.
+
+## Max dictionary bytes.
 fork_dictionary_bytes = "1GiB"
 
-# Log options, see `standalone.example.toml`
-# [logging]
-# dir = "/tmp/greptimedb/logs"
-# level = "info"
+## The logging options.
+[logging]
+## The directory to store the log files.
+dir = "/tmp/greptimedb/logs"
 
-# Datanode export the metrics generated by itself
-# encoded to Prometheus remote-write format
-# and send to Prometheus remote-write compatible receiver (e.g. send to `greptimedb` itself)
-# This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
-# [export_metrics]
-# whether enable export metrics, default is false
-# enable = false
-# The interval of export metrics
-# write_interval = "30s"
-# [export_metrics.remote_write]
-# The url the metrics send to. The url is empty by default, url example: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`
-# url = ""
-# HTTP headers of Prometheus remote-write carry
-# headers = {}
+## The log level. Can be `info`/`debug`/`warn`/`error`.
+## +toml2docs:none-default
+level = "info"
+
+## Enable OTLP tracing.
+enable_otlp_tracing = false
+
+## The OTLP tracing endpoint.
+## +toml2docs:none-default
+otlp_endpoint = ""
+
+## Whether to append logs to stdout.
+append_stdout = true
+
+## The percentage of tracing will be sampled and exported.
+## Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.
+## ratio > 1 are treated as 1. Fractions < 0 are treated as 0
+[logging.tracing_sample_ratio]
+default_ratio = 1.0
+
+## The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.
+## This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
+[export_metrics]
+
+## whether enable export metrics.
+enable = false
+
+## The interval of export metrics.
+write_interval = "30s"
+
+## For `standalone` mode, `self_import` is recommend to collect metrics generated by itself
+[export_metrics.self_import]
+## +toml2docs:none-default
+db = "information_schema"
+
+[export_metrics.remote_write]
+## The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`.
+url = ""
+
+## HTTP headers of Prometheus remote-write carry.
+headers = { }
diff --git a/config/frontend.example.toml b/config/frontend.example.toml
index dc9c6917bd..9123e4f8a0 100644
--- a/config/frontend.example.toml
+++ b/config/frontend.example.toml
@@ -1,106 +1,192 @@
-# Node running mode, see `standalone.example.toml`.
-mode = "distributed"
-# The default timezone of the server
-# default_timezone = "UTC"
+## The running mode of the datanode. It can be `standalone` or `distributed`.
+mode = "standalone"
 
+## The default timezone of the server.
+## +toml2docs:none-default
+default_timezone = "UTC"
+
+## The heartbeat options.
 [heartbeat]
-# Interval for sending heartbeat task to the Metasrv, 5 seconds by default.
-interval = "5s"
-# Interval for retry sending heartbeat task, 5 seconds by default.
-retry_interval = "5s"
+## Interval for sending heartbeat messages to the metasrv.
+interval = "18s"
 
-# HTTP server options, see `standalone.example.toml`.
+## Interval for retrying to send heartbeat messages to the metasrv.
+retry_interval = "3s"
+
+## The HTTP server options.
 [http]
+## The address to bind the HTTP server.
 addr = "127.0.0.1:4000"
+## HTTP request timeout.
 timeout = "30s"
+## HTTP request body limit.
+## Support the following units are supported: `B`, `KB`, `KiB`, `MB`, `MiB`, `GB`, `GiB`, `TB`, `TiB`, `PB`, `PiB`.
 body_limit = "64MB"
 
-# gRPC server options, see `standalone.example.toml`.
+## The gRPC server options.
 [grpc]
+## The address to bind the gRPC server.
 addr = "127.0.0.1:4001"
+## The number of server worker threads.
 runtime_size = 8
 
-# MySQL server options, see `standalone.example.toml`.
+## MySQL server options.
 [mysql]
+## Whether to enable.
 enable = true
+## The addr to bind the MySQL server.
 addr = "127.0.0.1:4002"
+## The number of server worker threads.
 runtime_size = 2
 
-# MySQL server TLS options, see `standalone.example.toml`.
+# MySQL server TLS options.
 [mysql.tls]
+
+## TLS mode, refer to https://www.postgresql.org/docs/current/libpq-ssl.html
+## - `disable` (default value)
+## - `prefer`
+## - `require`
+## - `verify-ca`
+## - `verify-full`
 mode = "disable"
+
+## Certificate file path.
+## +toml2docs:none-default
 cert_path = ""
+
+## Private key file path.
+## +toml2docs:none-default
 key_path = ""
+
+## Watch for Certificate and key file change and auto reload
 watch = false
 
-# PostgresSQL server options, see `standalone.example.toml`.
+## PostgresSQL server options.
 [postgres]
+## Whether to enable
 enable = true
+## The addr to bind the PostgresSQL server.
 addr = "127.0.0.1:4003"
+## The number of server worker threads.
 runtime_size = 2
 
-# PostgresSQL server TLS options, see `standalone.example.toml`.
+## PostgresSQL server TLS options, see `mysql_options.tls` section.
 [postgres.tls]
+## TLS mode.
 mode = "disable"
+
+## Certificate file path.
+## +toml2docs:none-default
 cert_path = ""
+
+## Private key file path.
+## +toml2docs:none-default
 key_path = ""
+
+## Watch for Certificate and key file change and auto reload
 watch = false
 
-# OpenTSDB protocol options, see `standalone.example.toml`.
+## OpenTSDB protocol options.
 [opentsdb]
+## Whether to enable
 enable = true
+## OpenTSDB telnet API server address.
 addr = "127.0.0.1:4242"
+## The number of server worker threads.
 runtime_size = 2
 
-# InfluxDB protocol options, see `standalone.example.toml`.
+## InfluxDB protocol options.
 [influxdb]
+## Whether to enable InfluxDB protocol in HTTP API.
 enable = true
 
-# Prometheus remote storage options, see `standalone.example.toml`.
+## Prometheus remote storage options
 [prom_store]
+## Whether to enable Prometheus remote write and read in HTTP API.
 enable = true
-# Whether to store the data from Prometheus remote write in metric engine.
-# true by default
+## Whether to store the data from Prometheus remote write in metric engine.
 with_metric_engine = true
 
-# Metasrv client options, see `datanode.example.toml`.
+## The metasrv client options.
 [meta_client]
+## The addresses of the metasrv.
 metasrv_addrs = ["127.0.0.1:3002"]
+
+## Operation timeout.
 timeout = "3s"
-# DDL timeouts options.
+
+## Heartbeat timeout.
+heartbeat_timeout = "500ms"
+
+## DDL timeout.
 ddl_timeout = "10s"
+
+## Connect server timeout.
 connect_timeout = "1s"
+
+## `TCP_NODELAY` option for accepted connections.
 tcp_nodelay = true
-# The configuration about the cache of the Metadata.
-# default: 100000
+
+## The configuration about the cache of the metadata.
 metadata_cache_max_capacity = 100000
-# default: 10m
+
+## TTL of the metadata cache.
 metadata_cache_ttl = "10m"
-# default: 5m
+
+# TTI of the metadata cache.
 metadata_cache_tti = "5m"
 
-# Log options, see `standalone.example.toml`
-# [logging]
-# dir = "/tmp/greptimedb/logs"
-# level = "info"
-
-# Datanode options.
+## Datanode options.
 [datanode]
-# Datanode client options.
+## Datanode client options.
 [datanode.client]
 timeout = "10s"
 connect_timeout = "10s"
 tcp_nodelay = true
 
-# Frontend export the metrics generated by itself
-# encoded to Prometheus remote-write format
-# and send to Prometheus remote-write compatible receiver (e.g. send to `greptimedb` itself)
-# This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
-# [export_metrics]
-# whether enable export metrics, default is false
-# enable = false
-# The interval of export metrics
-# write_interval = "30s"
-# for `frontend`, `self_import` is recommend to collect metrics generated by itself
-# [export_metrics.self_import]
-# db = "information_schema"
+## The logging options.
+[logging]
+## The directory to store the log files.
+dir = "/tmp/greptimedb/logs"
+
+## The log level. Can be `info`/`debug`/`warn`/`error`.
+## +toml2docs:none-default
+level = "info"
+
+## Enable OTLP tracing.
+enable_otlp_tracing = false
+
+## The OTLP tracing endpoint.
+## +toml2docs:none-default
+otlp_endpoint = ""
+
+## Whether to append logs to stdout.
+append_stdout = true
+
+## The percentage of tracing will be sampled and exported.
+## Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.
+## ratio > 1 are treated as 1. Fractions < 0 are treated as 0
+[logging.tracing_sample_ratio]
+default_ratio = 1.0
+
+## The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.
+## This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
+[export_metrics]
+
+## whether enable export metrics.
+enable = false
+
+## The interval of export metrics.
+write_interval = "30s"
+
+## For `standalone` mode, `self_import` is recommend to collect metrics generated by itself
+[export_metrics.self_import]
+## +toml2docs:none-default
+db = "information_schema"
+
+[export_metrics.remote_write]
+## The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`.
+url = ""
+
+## HTTP headers of Prometheus remote-write carry.
+headers = { }
diff --git a/config/metasrv.example.toml b/config/metasrv.example.toml
index 472a57e40a..1b0bca2e26 100644
--- a/config/metasrv.example.toml
+++ b/config/metasrv.example.toml
@@ -1,39 +1,44 @@
-# The working home directory.
+## The working home directory.
 data_home = "/tmp/metasrv/"
-# The bind address of metasrv, "127.0.0.1:3002" by default.
+
+## The bind address of metasrv.
 bind_addr = "127.0.0.1:3002"
-# The communication server address for frontend and datanode to connect to metasrv,  "127.0.0.1:3002" by default for localhost.
+
+## The communication server address for frontend and datanode to connect to metasrv,  "127.0.0.1:3002" by default for localhost.
 server_addr = "127.0.0.1:3002"
-# Etcd server address, "127.0.0.1:2379" by default.
+
+## Etcd server address.
 store_addr = "127.0.0.1:2379"
-# Datanode selector type.
-# - "lease_based" (default value).
-# - "load_based"
-# For details, please see "https://docs.greptime.com/developer-guide/metasrv/selector".
+
+## Datanode selector type.
+## - `lease_based` (default value).
+## - `load_based`
+## For details, please see "https://docs.greptime.com/developer-guide/metasrv/selector".
 selector = "lease_based"
-# Store data in memory, false by default.
+
+## Store data in memory.
 use_memory_store = false
-# Whether to enable greptimedb telemetry, true by default.
+
+## Whether to enable greptimedb telemetry.
 enable_telemetry = true
-# If it's not empty, the metasrv will store all data with this key prefix.
+
+## If it's not empty, the metasrv will store all data with this key prefix.
 store_key_prefix = ""
 
-# Log options, see `standalone.example.toml`
-# [logging]
-# dir = "/tmp/greptimedb/logs"
-# level = "info"
-
-# Procedure storage options.
+## Procedure storage options.
 [procedure]
-# Procedure max retry time.
+
+## Procedure max retry time.
 max_retry_times = 12
-# Initial retry delay of procedures, increases exponentially
+
+## Initial retry delay of procedures, increases exponentially
 retry_delay = "500ms"
-# Auto split large value
-# GreptimeDB procedure uses etcd as the default metadata storage backend.
-# The etcd the maximum size of any request is 1.5 MiB
-# 1500KiB = 1536KiB (1.5MiB) - 36KiB (reserved size of key)
-# Comments out the `max_metadata_value_size`, for don't split large value (no limit).
+
+## Auto split large value
+## GreptimeDB procedure uses etcd as the default metadata storage backend.
+## The etcd the maximum size of any request is 1.5 MiB
+## 1500KiB = 1536KiB (1.5MiB) - 36KiB (reserved size of key)
+## Comments out the `max_metadata_value_size`, for don't split large value (no limit).
 max_metadata_value_size = "1500KiB"
 
 # Failure detectors options.
@@ -43,57 +48,96 @@ min_std_deviation = "100ms"
 acceptable_heartbeat_pause = "3000ms"
 first_heartbeat_estimate = "1000ms"
 
-# # Datanode options.
-# [datanode]
-# # Datanode client options.
-# [datanode.client_options]
-# timeout = "10s"
-# connect_timeout = "10s"
-# tcp_nodelay = true
+## Datanode options.
+[datanode]
+## Datanode client options.
+[datanode.client]
+timeout = "10s"
+connect_timeout = "10s"
+tcp_nodelay = true
 
 [wal]
 # Available wal providers:
-# - "raft_engine" (default)
-# - "kafka"
+# - `raft_engine` (default): there're none raft-engine wal config since metasrv only involves in remote wal currently.
+# - `kafka`: metasrv **have to be** configured with kafka wal config when using kafka wal provider in datanode.
 provider = "raft_engine"
 
-# There're none raft-engine wal config since meta srv only involves in remote wal currently.
-
 # Kafka wal config.
-# The broker endpoints of the Kafka cluster. ["127.0.0.1:9092"] by default.
-# broker_endpoints = ["127.0.0.1:9092"]
-# Number of topics to be created upon start.
-# num_topics = 64
-# Topic selector type.
-# Available selector types: 
-# - "round_robin" (default)
-# selector_type = "round_robin"
-# A Kafka topic is constructed by concatenating `topic_name_prefix` and `topic_id`.
-# topic_name_prefix = "greptimedb_wal_topic"
-# Expected number of replicas of each partition.
-# replication_factor = 1
-# Above which a topic creation operation will be cancelled.
-# create_topic_timeout = "30s"
-# The initial backoff for kafka clients.
-# backoff_init = "500ms"
-# The maximum backoff for kafka clients.
-# backoff_max = "10s"
-# Exponential backoff rate, i.e. next backoff = base * current backoff.
-# backoff_base = 2
-# Stop reconnecting if the total wait time reaches the deadline. If this config is missing, the reconnecting won't terminate.
-# backoff_deadline = "5mins"
 
-# Metasrv export the metrics generated by itself
-# encoded to Prometheus remote-write format
-# and send to Prometheus remote-write compatible receiver (e.g. send to `greptimedb` itself)
-# This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
-# [export_metrics]
-# whether enable export metrics, default is false
-# enable = false
-# The interval of export metrics
-# write_interval = "30s"
-# [export_metrics.remote_write]
-# The url the metrics send to. The url is empty by default, url example: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`
-# url = ""
-# HTTP headers of Prometheus remote-write carry
-# headers = {}
+## The broker endpoints of the Kafka cluster.
+broker_endpoints = ["127.0.0.1:9092"]
+
+## Number of topics to be created upon start.
+num_topics = 64
+
+## Topic selector type.
+## Available selector types:
+## - `round_robin` (default)
+selector_type = "round_robin"
+
+## A Kafka topic is constructed by concatenating `topic_name_prefix` and `topic_id`.
+topic_name_prefix = "greptimedb_wal_topic"
+
+## Expected number of replicas of each partition.
+replication_factor = 1
+
+## Above which a topic creation operation will be cancelled.
+create_topic_timeout = "30s"
+## The initial backoff for kafka clients.
+backoff_init = "500ms"
+
+## The maximum backoff for kafka clients.
+backoff_max = "10s"
+
+## Exponential backoff rate, i.e. next backoff = base * current backoff.
+backoff_base = 2
+
+## Stop reconnecting if the total wait time reaches the deadline. If this config is missing, the reconnecting won't terminate.
+backoff_deadline = "5mins"
+
+## The logging options.
+[logging]
+## The directory to store the log files.
+dir = "/tmp/greptimedb/logs"
+
+## The log level. Can be `info`/`debug`/`warn`/`error`.
+## +toml2docs:none-default
+level = "info"
+
+## Enable OTLP tracing.
+enable_otlp_tracing = false
+
+## The OTLP tracing endpoint.
+## +toml2docs:none-default
+otlp_endpoint = ""
+
+## Whether to append logs to stdout.
+append_stdout = true
+
+## The percentage of tracing will be sampled and exported.
+## Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.
+## ratio > 1 are treated as 1. Fractions < 0 are treated as 0
+[logging.tracing_sample_ratio]
+default_ratio = 1.0
+
+## The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.
+## This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
+[export_metrics]
+
+## whether enable export metrics.
+enable = false
+
+## The interval of export metrics.
+write_interval = "30s"
+
+## For `standalone` mode, `self_import` is recommend to collect metrics generated by itself
+[export_metrics.self_import]
+## +toml2docs:none-default
+db = "information_schema"
+
+[export_metrics.remote_write]
+## The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`.
+url = ""
+
+## HTTP headers of Prometheus remote-write carry.
+headers = { }
diff --git a/config/standalone.example.toml b/config/standalone.example.toml
index 916e536a82..189e679e86 100644
--- a/config/standalone.example.toml
+++ b/config/standalone.example.toml
@@ -1,284 +1,474 @@
-# Node running mode, "standalone" or "distributed".
+## The running mode of the datanode. It can be `standalone` or `distributed`.
 mode = "standalone"
-# Whether to enable greptimedb telemetry, true by default.
-enable_telemetry = true
-# The default timezone of the server
-# default_timezone = "UTC"
 
-# HTTP server options.
+## Enable telemetry to collect anonymous usage data.
+enable_telemetry = true
+
+## The default timezone of the server.
+## +toml2docs:none-default
+default_timezone = "UTC"
+
+## The HTTP server options.
 [http]
-# Server address, "127.0.0.1:4000" by default.
+## The address to bind the HTTP server.
 addr = "127.0.0.1:4000"
-# HTTP request timeout, 30s by default.
+## HTTP request timeout.
 timeout = "30s"
-# HTTP request body limit, 64Mb by default.
-# the following units are supported: B, KB, KiB, MB, MiB, GB, GiB, TB, TiB, PB, PiB
+## HTTP request body limit.
+## Support the following units are supported: `B`, `KB`, `KiB`, `MB`, `MiB`, `GB`, `GiB`, `TB`, `TiB`, `PB`, `PiB`.
 body_limit = "64MB"
 
-# gRPC server options.
+## The gRPC server options.
 [grpc]
-# Server address, "127.0.0.1:4001" by default.
+## The address to bind the gRPC server.
 addr = "127.0.0.1:4001"
-# The number of server worker threads, 8 by default.
+## The number of server worker threads.
 runtime_size = 8
 
-# MySQL server options.
+## MySQL server options.
 [mysql]
-# Whether to enable
+## Whether to enable.
 enable = true
-# Server address, "127.0.0.1:4002" by default.
+## The addr to bind the MySQL server.
 addr = "127.0.0.1:4002"
-# The number of server worker threads, 2 by default.
+## The number of server worker threads.
 runtime_size = 2
 
 # MySQL server TLS options.
 [mysql.tls]
-# TLS mode, refer to https://www.postgresql.org/docs/current/libpq-ssl.html
-# - "disable" (default value)
-# - "prefer"
-# - "require"
-# - "verify-ca"
-# - "verify-full"
+
+## TLS mode, refer to https://www.postgresql.org/docs/current/libpq-ssl.html
+## - `disable` (default value)
+## - `prefer`
+## - `require`
+## - `verify-ca`
+## - `verify-full`
 mode = "disable"
-# Certificate file path.
+
+## Certificate file path.
+## +toml2docs:none-default
 cert_path = ""
-# Private key file path.
+
+## Private key file path.
+## +toml2docs:none-default
 key_path = ""
-# Watch for Certificate and key file change and auto reload
+
+## Watch for Certificate and key file change and auto reload
 watch = false
 
-# PostgresSQL server options.
+## PostgresSQL server options.
 [postgres]
-# Whether to enable
+## Whether to enable
 enable = true
-# Server address, "127.0.0.1:4003" by default.
+## The addr to bind the PostgresSQL server.
 addr = "127.0.0.1:4003"
-# The number of server worker threads, 2 by default.
+## The number of server worker threads.
 runtime_size = 2
 
-# PostgresSQL server TLS options, see `[mysql_options.tls]` section.
+## PostgresSQL server TLS options, see `mysql_options.tls` section.
 [postgres.tls]
-# TLS mode.
+## TLS mode.
 mode = "disable"
-# certificate file path.
+
+## Certificate file path.
+## +toml2docs:none-default
 cert_path = ""
-# private key file path.
+
+## Private key file path.
+## +toml2docs:none-default
 key_path = ""
-# Watch for Certificate and key file change and auto reload
+
+## Watch for Certificate and key file change and auto reload
 watch = false
 
-# OpenTSDB protocol options.
+## OpenTSDB protocol options.
 [opentsdb]
-# Whether to enable
+## Whether to enable
 enable = true
-# OpenTSDB telnet API server address, "127.0.0.1:4242" by default.
+## OpenTSDB telnet API server address.
 addr = "127.0.0.1:4242"
-# The number of server worker threads, 2 by default.
+## The number of server worker threads.
 runtime_size = 2
 
-# InfluxDB protocol options.
+## InfluxDB protocol options.
 [influxdb]
-# Whether to enable InfluxDB protocol in HTTP API, true by default.
+## Whether to enable InfluxDB protocol in HTTP API.
 enable = true
 
-# Prometheus remote storage options
+## Prometheus remote storage options
 [prom_store]
-# Whether to enable Prometheus remote write and read in HTTP API, true by default.
+## Whether to enable Prometheus remote write and read in HTTP API.
 enable = true
-# Whether to store the data from Prometheus remote write in metric engine.
-# true by default
+## Whether to store the data from Prometheus remote write in metric engine.
 with_metric_engine = true
 
+## The WAL options.
 [wal]
-# Available wal providers:
-# - "raft_engine" (default)
-# - "kafka"
+## The provider of the WAL.
+## - `raft_engine`: the wal is stored in the local file system by raft-engine.
+## - `kafka`: it's remote wal that data is stored in Kafka.
 provider = "raft_engine"
 
-# Raft-engine wal options.
-# WAL data directory
-# dir = "/tmp/greptimedb/wal"
-# WAL file size in bytes.
+## The directory to store the WAL files.
+## **It's only used when the provider is `raft_engine`**.
+## +toml2docs:none-default
+dir = "/tmp/greptimedb/wal"
+
+## The size of the WAL segment file.
+## **It's only used when the provider is `raft_engine`**.
 file_size = "256MB"
-# WAL purge threshold.
+
+## The threshold of the WAL size to trigger a flush.
+## **It's only used when the provider is `raft_engine`**.
 purge_threshold = "4GB"
-# WAL purge interval in seconds.
+
+## The interval to trigger a flush.
+## **It's only used when the provider is `raft_engine`**.
 purge_interval = "10m"
-# WAL read batch size.
+
+## The read batch size.
+## **It's only used when the provider is `raft_engine`**.
 read_batch_size = 128
-# Whether to sync log file after every write.
+
+## Whether to use sync write.
+## **It's only used when the provider is `raft_engine`**.
 sync_write = false
-# Whether to reuse logically truncated log files.
+
+## Whether to reuse logically truncated log files.
+## **It's only used when the provider is `raft_engine`**.
 enable_log_recycle = true
-# Whether to pre-create log files on start up
+
+## Whether to pre-create log files on start up.
+## **It's only used when the provider is `raft_engine`**.
 prefill_log_files = false
-# Duration for fsyncing log files.
-sync_period = "1000ms"
 
-# Kafka wal options.
-# The broker endpoints of the Kafka cluster. ["127.0.0.1:9092"] by default.
-# broker_endpoints = ["127.0.0.1:9092"]
+## Duration for fsyncing log files.
+## **It's only used when the provider is `raft_engine`**.
+sync_period = "10s"
 
-# Number of topics to be created upon start.
-# num_topics = 64
-# Topic selector type.
-# Available selector types:
-# - "round_robin" (default)
-# selector_type = "round_robin"
-# The prefix of topic name.
-# topic_name_prefix = "greptimedb_wal_topic"
-# The number of replicas of each partition.
-# Warning: the replication factor must be positive and must not be greater than the number of broker endpoints.
-# replication_factor = 1
+## The Kafka broker endpoints.
+## **It's only used when the provider is `kafka`**.
+broker_endpoints = ["127.0.0.1:9092"]
 
-# The max size of a single producer batch.
-# Warning: Kafka has a default limit of 1MB per message in a topic.
-# max_batch_size = "1MB"
-# The linger duration.
-# linger = "200ms"
-# The consumer wait timeout.
-# consumer_wait_timeout = "100ms"
-# Create topic timeout.
-# create_topic_timeout = "30s"
+## The max size of a single producer batch.
+## Warning: Kafka has a default limit of 1MB per message in a topic.
+## **It's only used when the provider is `kafka`**.
+max_batch_size = "1MB"
 
-# The initial backoff delay.
-# backoff_init = "500ms"
-# The maximum backoff delay.
-# backoff_max = "10s"
-# Exponential backoff rate, i.e. next backoff = base * current backoff.
-# backoff_base = 2
-# The deadline of retries.
-# backoff_deadline = "5mins"
+## The linger duration of a kafka batch producer.
+## **It's only used when the provider is `kafka`**.
+linger = "200ms"
 
-# Metadata storage options.
+## The consumer wait timeout.
+## **It's only used when the provider is `kafka`**.
+consumer_wait_timeout = "100ms"
+
+## The initial backoff delay.
+## **It's only used when the provider is `kafka`**.
+backoff_init = "500ms"
+
+## The maximum backoff delay.
+## **It's only used when the provider is `kafka`**.
+backoff_max = "10s"
+
+## The exponential backoff rate, i.e. next backoff = base * current backoff.
+## **It's only used when the provider is `kafka`**.
+backoff_base = 2
+
+## The deadline of retries.
+## **It's only used when the provider is `kafka`**.
+backoff_deadline = "5mins"
+
+## Metadata storage options.
 [metadata_store]
-# Kv file size in bytes.
+## Kv file size in bytes.
 file_size = "256MB"
-# Kv purge threshold.
+## Kv purge threshold.
 purge_threshold = "4GB"
 
-# Procedure storage options.
+## Procedure storage options.
 [procedure]
-# Procedure max retry time.
+## Procedure max retry time.
 max_retry_times = 3
-# Initial retry delay of procedures, increases exponentially
+## Initial retry delay of procedures, increases exponentially
 retry_delay = "500ms"
 
-# Storage options.
+# Example of using S3 as the storage.
+# [storage]
+# type = "S3"
+# bucket = "greptimedb"
+# root = "data"
+# access_key_id = "test"
+# secret_access_key = "123456"
+# endpoint = "https://s3.amazonaws.com"
+# region = "us-west-2"
+
+# Example of using Oss as the storage.
+# [storage]
+# type = "Oss"
+# bucket = "greptimedb"
+# root = "data"
+# access_key_id = "test"
+# access_key_secret = "123456"
+# endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
+
+# Example of using Azblob as the storage.
+# [storage]
+# type = "Azblob"
+# container = "greptimedb"
+# root = "data"
+# account_name = "test"
+# account_key = "123456"
+# endpoint = "https://greptimedb.blob.core.windows.net"
+# sas_token = ""
+
+# Example of using Gcs as the storage.
+# [storage]
+# type = "Gcs"
+# bucket = "greptimedb"
+# root = "data"
+# scope = "test"
+# credential_path = "123456"
+# endpoint = "https://storage.googleapis.com"
+
+## The data storage options.
 [storage]
-# The working home directory.
+## The working home directory.
 data_home = "/tmp/greptimedb/"
-# Storage type.
+
+## The storage type used to store the data.
+## - `File`: the data is stored in the local file system.
+## - `S3`: the data is stored in the S3 object storage.
+## - `Gcs`: the data is stored in the Google Cloud Storage.
+## - `Azblob`: the data is stored in the Azure Blob Storage.
+## - `Oss`: the data is stored in the Aliyun OSS.
 type = "File"
-# Cache configuration for object storage such as 'S3' etc.
-# cache_path = "/path/local_cache"
-# The local file cache capacity in bytes.
-# cache_capacity = "256MB"
+
+## Cache configuration for object storage such as 'S3' etc.
+## The local file cache directory.
+## +toml2docs:none-default
+cache_path = "/path/local_cache"
+
+## The local file cache capacity in bytes.
+## +toml2docs:none-default
+cache_capacity = "256MB"
+
+## The S3 bucket name.
+## **It's only used when the storage type is `S3`, `Oss` and `Gcs`**.
+## +toml2docs:none-default
+bucket = "greptimedb"
+
+## The S3 data will be stored in the specified prefix, for example, `s3://${bucket}/${root}`.
+## **It's only used when the storage type is `S3`, `Oss` and `Azblob`**.
+## +toml2docs:none-default
+root = "greptimedb"
+
+## The access key id of the aws account.
+## It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.
+## **It's only used when the storage type is `S3` and `Oss`**.
+## +toml2docs:none-default
+access_key_id = "test"
+
+## The secret access key of the aws account.
+## It's **highly recommended** to use AWS IAM roles instead of hardcoding the access key id and secret key.
+## **It's only used when the storage type is `S3`**.
+## +toml2docs:none-default
+secret_access_key = "test"
+
+## The secret access key of the aliyun account.
+## **It's only used when the storage type is `Oss`**.
+## +toml2docs:none-default
+access_key_secret = "test"
+
+## The account key of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+account_name = "test"
+
+## The account key of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+account_key = "test"
+
+## The scope of the google cloud storage.
+## **It's only used when the storage type is `Gcs`**.
+## +toml2docs:none-default
+scope = "test"
+
+## The credential path of the google cloud storage.
+## **It's only used when the storage type is `Gcs`**.
+## +toml2docs:none-default
+credential_path = "test"
+
+## The container of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+container = "greptimedb"
+
+## The sas token of the azure account.
+## **It's only used when the storage type is `Azblob`**.
+## +toml2docs:none-default
+sas_token = ""
+
+## The endpoint of the S3 service.
+## **It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**.
+## +toml2docs:none-default
+endpoint = "https://s3.amazonaws.com"
+
+## The region of the S3 service.
+## **It's only used when the storage type is `S3`, `Oss`, `Gcs` and `Azblob`**.
+## +toml2docs:none-default
+region = "us-west-2"
 
 # Custom storage options
-#[[storage.providers]]
-#type = "S3"
-#[[storage.providers]]
-#type = "Gcs"
+# [[storage.providers]]
+# type = "S3"
+# [[storage.providers]]
+# type = "Gcs"
 
-# Mito engine options
+## The region engine options. You can configure multiple region engines.
 [[region_engine]]
+
+## The Mito engine options.
 [region_engine.mito]
-# Number of region workers
+
+## Number of region workers.
 num_workers = 8
-# Request channel size of each worker
+
+## Request channel size of each worker.
 worker_channel_size = 128
-# Max batch size for a worker to handle requests
+
+## Max batch size for a worker to handle requests.
 worker_request_batch_size = 64
-# Number of meta action updated to trigger a new checkpoint for the manifest
+
+## Number of meta action updated to trigger a new checkpoint for the manifest.
 manifest_checkpoint_distance = 10
-# Whether to compress manifest and checkpoint file by gzip (default false).
+
+## Whether to compress manifest and checkpoint file by gzip (default false).
 compress_manifest = false
-# Max number of running background jobs
+
+## Max number of running background jobs
 max_background_jobs = 4
-# Interval to auto flush a region if it has not flushed yet.
+
+## Interval to auto flush a region if it has not flushed yet.
 auto_flush_interval = "1h"
-# Global write buffer size for all regions. If not set, it's default to 1/8 of OS memory with a max limitation of 1GB.
+
+## Global write buffer size for all regions. If not set, it's default to 1/8 of OS memory with a max limitation of 1GB.
 global_write_buffer_size = "1GB"
-# Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size`
+
+## Global write buffer size threshold to reject write requests. If not set, it's default to 2 times of `global_write_buffer_size`
 global_write_buffer_reject_size = "2GB"
-# Cache size for SST metadata. Setting it to 0 to disable the cache.
-# If not set, it's default to 1/32 of OS memory with a max limitation of 128MB.
+
+## Cache size for SST metadata. Setting it to 0 to disable the cache.
+## If not set, it's default to 1/32 of OS memory with a max limitation of 128MB.
 sst_meta_cache_size = "128MB"
-# Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.
-# If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+
+## Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.
+## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
 vector_cache_size = "512MB"
-# Cache size for pages of SST row groups. Setting it to 0 to disable the cache.
-# If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
+
+## Cache size for pages of SST row groups. Setting it to 0 to disable the cache.
+## If not set, it's default to 1/16 of OS memory with a max limitation of 512MB.
 page_cache_size = "512MB"
-# Buffer size for SST writing.
+
+## Buffer size for SST writing.
 sst_write_buffer_size = "8MB"
-# Parallelism to scan a region (default: 1/4 of cpu cores).
-# - 0: using the default value (1/4 of cpu cores).
-# - 1: scan in current thread.
-# - n: scan in parallelism n.
+
+## Parallelism to scan a region (default: 1/4 of cpu cores).
+## - `0`: using the default value (1/4 of cpu cores).
+## - `1`: scan in current thread.
+## - `n`: scan in parallelism n.
 scan_parallelism = 0
-# Capacity of the channel to send data from parallel scan tasks to the main task (default 32).
+
+## Capacity of the channel to send data from parallel scan tasks to the main task.
 parallel_scan_channel_size = 32
-# Whether to allow stale WAL entries read during replay.
+
+## Whether to allow stale WAL entries read during replay.
 allow_stale_entries = false
 
+## The options for inverted index in Mito engine.
 [region_engine.mito.inverted_index]
-# Whether to create the index on flush.
-# - "auto": automatically
-# - "disable": never
+
+## Whether to create the index on flush.
+## - `auto`: automatically
+## - `disable`: never
 create_on_flush = "auto"
-# Whether to create the index on compaction.
-# - "auto": automatically
-# - "disable": never
+
+## Whether to create the index on compaction.
+## - `auto`: automatically
+## - `disable`: never
 create_on_compaction = "auto"
-# Whether to apply the index on query
-# - "auto": automatically
-# - "disable": never
+
+## Whether to apply the index on query
+## - `auto`: automatically
+## - `disable`: never
 apply_on_query = "auto"
-# Memory threshold for performing an external sort during index creation.
-# Setting to empty will disable external sorting, forcing all sorting operations to happen in memory.
+
+## Memory threshold for performing an external sort during index creation.
+## Setting to empty will disable external sorting, forcing all sorting operations to happen in memory.
 mem_threshold_on_create = "64M"
-# File system path to store intermediate files for external sorting (default `{data_home}/index_intermediate`).
+
+## File system path to store intermediate files for external sorting (default `{data_home}/index_intermediate`).
 intermediate_path = ""
 
 [region_engine.mito.memtable]
-# Memtable type.
-# - "partition_tree": partition tree memtable
-# - "time_series": time-series memtable (deprecated)
+## Memtable type.
+## - `partition_tree`: partition tree memtable
+## - `time_series`: time-series memtable (deprecated)
 type = "partition_tree"
-# The max number of keys in one shard.
+
+## The max number of keys in one shard.
 index_max_keys_per_shard = 8192
-# The max rows of data inside the actively writing buffer in one shard.
+
+## The max rows of data inside the actively writing buffer in one shard.
 data_freeze_threshold = 32768
-# Max dictionary bytes.
+
+## Max dictionary bytes.
 fork_dictionary_bytes = "1GiB"
 
-# Log options
-# [logging]
-# Specify logs directory.
-# dir = "/tmp/greptimedb/logs"
-# Specify the log level [info | debug | error | warn]
-# level = "info"
-# whether enable tracing, default is false
-# enable_otlp_tracing = false
-# tracing exporter endpoint with format `ip:port`, we use grpc oltp as exporter, default endpoint is `localhost:4317`
-# otlp_endpoint = "localhost:4317"
-# Whether to append logs to stdout. Defaults to true.
-# append_stdout = true
-# The percentage of tracing will be sampled and exported. Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1. ratio > 1 are treated as 1. Fractions < 0 are treated as 0
-# [logging.tracing_sample_ratio]
-# default_ratio = 0.0
+## The logging options.
+[logging]
+## The directory to store the log files.
+dir = "/tmp/greptimedb/logs"
 
-# Standalone export the metrics generated by itself
-# encoded to Prometheus remote-write format
-# and send to Prometheus remote-write compatible receiver (e.g. send to `greptimedb` itself)
-# This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
-# [export_metrics]
-# whether enable export metrics, default is false
-# enable = false
-# The interval of export metrics
-# write_interval = "30s"
-# for `standalone`, `self_import` is recommend to collect metrics generated by itself
-# [export_metrics.self_import]
-# db = "information_schema"
+## The log level. Can be `info`/`debug`/`warn`/`error`.
+## +toml2docs:none-default
+level = "info"
+
+## Enable OTLP tracing.
+enable_otlp_tracing = false
+
+## The OTLP tracing endpoint.
+## +toml2docs:none-default
+otlp_endpoint = ""
+
+## Whether to append logs to stdout.
+append_stdout = true
+
+## The percentage of tracing will be sampled and exported.
+## Valid range `[0, 1]`, 1 means all traces are sampled, 0 means all traces are not sampled, the default value is 1.
+## ratio > 1 are treated as 1. Fractions < 0 are treated as 0
+[logging.tracing_sample_ratio]
+default_ratio = 1.0
+
+## The datanode can export its metrics and send to Prometheus compatible service (e.g. send to `greptimedb` itself) from remote-write API.
+## This is only used for `greptimedb` to export its own metrics internally. It's different from prometheus scrape.
+[export_metrics]
+
+## whether enable export metrics.
+enable = false
+
+## The interval of export metrics.
+write_interval = "30s"
+
+## For `standalone` mode, `self_import` is recommend to collect metrics generated by itself
+[export_metrics.self_import]
+## +toml2docs:none-default
+db = "information_schema"
+
+[export_metrics.remote_write]
+## The url the metrics send to. The url example can be: `http://127.0.0.1:4000/v1/prometheus/write?db=information_schema`.
+url = ""
+
+## HTTP headers of Prometheus remote-write carry.
+headers = { }