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API Reference

Arc provides a comprehensive REST API for data ingestion, querying, and management.

Base URL​

http://localhost:8000

Authentication​

All endpoints (except public ones) require Bearer token authentication:

curl -H "Authorization: Bearer YOUR_TOKEN" http://localhost:8000/api/v1/query

Or use the x-api-key header:

curl -H "x-api-key: YOUR_TOKEN" http://localhost:8000/api/v1/query

Public Endpoints (No Auth Required)​

  • GET /health - Health check
  • GET /ready - Readiness probe
  • GET /metrics - Prometheus metrics
  • GET /api/v1/auth/verify - Token verification

Quick Examples​

Write Data (MessagePack)​

import msgpack
import requests

data = {
    "m": "cpu",
    "columns": {
        "time": [1697472000000],
        "host": ["server01"],
        "usage": [45.2]
    }
}

response = requests.post(
    "http://localhost:8000/api/v1/write/msgpack",
    headers={
        "Authorization": "Bearer YOUR_TOKEN",
        "Content-Type": "application/msgpack",
        "x-arc-database": "default"
    },
    data=msgpack.packb(data)
)

Query Data (JSON)​

curl -X POST http://localhost:8000/api/v1/query \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"sql": "SELECT * FROM default.cpu LIMIT 10", "format": "json"}'

Query Data (Apache Arrow)​

For large result sets, use Arrow format for 2.88M rows/sec throughput:

import requests
import pyarrow as pa

response = requests.post(
    "http://localhost:8000/api/v1/query/arrow",
    headers={"Authorization": "Bearer YOUR_TOKEN"},
    json={"sql": "SELECT * FROM default.cpu LIMIT 100000"}
)

reader = pa.ipc.open_stream(response.content)
arrow_table = reader.read_all()

Health Check​

curl http://localhost:8000/health

Health & Monitoring​

GET /health​

Health check endpoint.

Response:

{
  "status": "ok",
  "time": "2024-12-02T10:30:00Z",
  "uptime": "1h 23m 45s",
  "uptime_sec": 5025
}

GET /ready​

Kubernetes readiness probe.

Response:

{
  "status": "ready",
  "time": "2024-12-02T10:30:00Z",
  "uptime_sec": 5025
}

GET /metrics​

Prometheus-format metrics.

Response: text/plain (Prometheus format)

Or request JSON:

curl -H "Accept: application/json" http://localhost:8000/metrics

GET /api/v1/metrics​

All metrics in JSON format.

GET /api/v1/metrics/memory​

Detailed memory statistics including Go runtime and DuckDB.

GET /api/v1/metrics/query-pool​

DuckDB connection pool statistics.

GET /api/v1/metrics/endpoints​

Per-endpoint request statistics.

GET /api/v1/metrics/timeseries/:type​

Timeseries metrics data.

Parameters:

  • :type - system, application, or api
  • ?duration_minutes=30 - Time range (default: 30, max: 1440)

GET /api/v1/logs​

Recent application logs.

Query Parameters:

  • ?limit=100 - Number of logs (default: 100, max: 1000)
  • ?level=error - Filter by level (error, warn, info, debug)
  • ?since_minutes=60 - Time range (default: 60, max: 1440)

Data Ingestion​

POST /api/v1/write/msgpack​

High-performance MessagePack binary writes (recommended).

Headers:

  • Authorization: Bearer TOKEN
  • Content-Type: application/msgpack
  • Content-Encoding: gzip (optional)
  • x-arc-database: default (optional)

Body (MessagePack):

{
  "m": "measurement_name",
  "columns": {
    "time": [1697472000000, 1697472001000],
    "host": ["server01", "server02"],
    "value": [45.2, 67.8]
  }
}

Response: 204 No Content

GET /api/v1/write/msgpack/stats​

MessagePack ingestion statistics.

GET /api/v1/write/msgpack/spec​

MessagePack format specification.

POST /api/v1/write​

InfluxDB 1.x Line Protocol compatible.

Headers:

  • Content-Type: text/plain
  • x-arc-database: default (optional)

Body:

cpu,host=server01 usage=45.2 1697472000000000000
mem,host=server01 used=8.2,total=16.0 1697472000000000000

POST /api/v1/write/influxdb​

InfluxDB 2.x compatible endpoint.

POST /api/v1/write/line-protocol​

Standard Line Protocol endpoint.

POST /api/v1/write/line-protocol/flush​

Force buffer flush to disk.

GET /api/v1/write/line-protocol/stats​

Line Protocol ingestion statistics.

GET /api/v1/write/line-protocol/health​

Line Protocol handler health.

Querying​

POST /api/v1/query​

Execute SQL queries with JSON response.

Request:

{
  "sql": "SELECT * FROM default.cpu LIMIT 10",
  "format": "json"
}

Response:

{
  "columns": ["time", "host", "usage"],
  "types": ["TIMESTAMP", "VARCHAR", "DOUBLE"],
  "data": [
    [1697472000000, "server01", 45.2],
    [1697472001000, "server02", 67.8]
  ],
  "row_count": 2,
  "execution_time_ms": 12
}

POST /api/v1/query/arrow​

Execute SQL queries with Apache Arrow IPC response.

Request:

{
  "sql": "SELECT * FROM default.cpu LIMIT 10000"
}

Response: application/vnd.apache.arrow.stream

POST /api/v1/query/estimate​

Estimate query cost before execution.

Request:

{
  "sql": "SELECT * FROM default.cpu WHERE time > now() - INTERVAL '1 hour'"
}

GET /api/v1/measurements​

List all measurements across databases.

GET /api/v1/query/:measurement​

Query a specific measurement directly.

Authentication​

GET /api/v1/auth/verify​

Verify token validity (public endpoint).

Response:

{
  "valid": true,
  "token_id": "abc123",
  "name": "my-token",
  "is_admin": false
}

GET /api/v1/auth/tokens​

List all tokens (admin only).

POST /api/v1/auth/tokens​

Create a new token (admin only).

Request:

{
  "name": "my-service",
  "description": "Token for my service",
  "is_admin": false
}

Response:

{
  "id": "abc123",
  "name": "my-service",
  "token": "arc_xxxxxxxxxxxxxxxxxxxxxxxx",
  "is_admin": false,
  "created_at": "2024-12-02T10:30:00Z"
}

GET /api/v1/auth/tokens/:id​

Get token details (admin only).

DELETE /api/v1/auth/tokens/:id​

Delete/revoke a token (admin only).

POST /api/v1/auth/tokens/:id/rotate​

Rotate a token (admin only).

POST /api/v1/auth/tokens/:id/revoke​

Revoke a token (admin only).

GET /api/v1/auth/cache/stats​

Token cache statistics (admin only).

POST /api/v1/auth/cache/invalidate​

Invalidate token cache (admin only).

Compaction​

GET /api/v1/compaction/status​

Current compaction status.

Response:

{
  "enabled": true,
  "running": false,
  "last_run": "2024-12-02T10:00:00Z",
  "next_run": "2024-12-02T11:00:00Z"
}

GET /api/v1/compaction/stats​

Compaction statistics.

GET /api/v1/compaction/candidates​

List files eligible for compaction.

POST /api/v1/compaction/trigger​

Manually trigger compaction.

Request:

{
  "database": "default",
  "measurement": "cpu"
}

GET /api/v1/compaction/jobs​

List active compaction jobs.

GET /api/v1/compaction/history​

Compaction job history.

Delete Operations​

POST /api/v1/delete​

Delete data matching conditions.

Request:

{
  "database": "default",
  "measurement": "cpu",
  "where": "host = 'server01' AND time < '2024-01-01'",
  "confirm": true
}

Response:

{
  "deleted_rows": 1523,
  "deleted_files": 3
}

GET /api/v1/delete/config​

Get delete operation configuration.

Database Management​

Endpoints for managing databases programmatically.

GET /api/v1/databases​

List all databases with measurement counts.

Response:

{
  "databases": [
    {"name": "default", "measurement_count": 5},
    {"name": "production", "measurement_count": 12}
  ],
  "count": 2
}

POST /api/v1/databases​

Create a new database.

Request:

{
  "name": "my_database"
}

Response (201 Created):

{
  "name": "my_database",
  "measurement_count": 0,
  "created_at": "2024-12-21T10:30:00Z"
}

Validation rules:

  • Must start with a letter (a-z, A-Z)
  • Can contain letters, numbers, underscores, and hyphens
  • Maximum 64 characters
  • Reserved names blocked: system, internal, _internal

Error Response (400):

{
  "error": "Invalid database name: must start with a letter and contain only alphanumeric characters, underscores, or hyphens"
}

GET /api/v1/databases/:name​

Get information about a specific database.

Response:

{
  "name": "production",
  "measurement_count": 12
}

Error Response (404):

{
  "error": "Database 'nonexistent' not found"
}

GET /api/v1/databases/:name/measurements​

List all measurements in a database.

Response:

{
  "database": "production",
  "measurements": [
    {"name": "cpu"},
    {"name": "memory"},
    {"name": "disk"}
  ],
  "count": 3
}

DELETE /api/v1/databases/:name​

Delete a database and all its data.

caution

This operation is destructive and cannot be undone. Requires:

  • delete.enabled = true in configuration
  • ?confirm=true query parameter

Request:

curl -X DELETE -H "Authorization: Bearer $TOKEN" \
  "http://localhost:8000/api/v1/databases/old_data?confirm=true"

Response:

{
  "message": "Database 'old_data' deleted successfully",
  "files_deleted": 47
}

Error Responses:

Delete disabled (403):

{
  "error": "Delete operations are disabled. Set delete.enabled=true in arc.toml to enable."
}

Missing confirmation (400):

{
  "error": "Confirmation required. Add ?confirm=true to delete the database."
}

Retention Policies​

POST /api/v1/retention​

Create a retention policy.

Request:

{
  "name": "30-day-retention",
  "database": "default",
  "measurement": "cpu",
  "duration": "30d",
  "schedule": "0 2 * * *"
}

GET /api/v1/retention​

List all retention policies.

GET /api/v1/retention/:id​

Get a specific policy.

PUT /api/v1/retention/:id​

Update a retention policy.

DELETE /api/v1/retention/:id​

Delete a retention policy.

POST /api/v1/retention/:id/execute​

Execute a policy manually.

GET /api/v1/retention/:id/executions​

Get policy execution history.

Continuous Queries​

POST /api/v1/continuous_queries​

Create a continuous query.

Request:

{
  "name": "hourly-rollup",
  "source_database": "default",
  "source_measurement": "cpu",
  "destination_database": "default",
  "destination_measurement": "cpu_hourly",
  "query": "SELECT time_bucket('1 hour', time) as time, host, AVG(usage) as avg_usage FROM default.cpu GROUP BY 1, 2",
  "schedule": "0 * * * *"
}

GET /api/v1/continuous_queries​

List all continuous queries.

GET /api/v1/continuous_queries/:id​

Get a specific continuous query.

PUT /api/v1/continuous_queries/:id​

Update a continuous query.

DELETE /api/v1/continuous_queries/:id​

Delete a continuous query.

POST /api/v1/continuous_queries/:id/execute​

Execute a continuous query manually.

GET /api/v1/continuous_queries/:id/executions​

Get execution history.

MQTT Subscriptions​

Available since v26.02.1

MQTT subscription management is available starting Arc v26.02.1.

Manage MQTT broker subscriptions for direct IoT data ingestion. See the MQTT Integration Guide for detailed usage.

POST /api/v1/mqtt/subscriptions​

Create a new MQTT subscription.

Request:

{
  "name": "factory-sensors",
  "broker": "tcp://localhost:1883",
  "topics": ["sensors/#"],
  "database": "iot",
  "qos": 1,
  "auto_start": true
}

Response (201 Created):

{
  "id": "sub_abc123",
  "name": "factory-sensors",
  "broker": "tcp://localhost:1883",
  "topics": ["sensors/#"],
  "database": "iot",
  "status": "running",
  "created_at": "2026-02-01T10:00:00Z"
}

Full options:

FieldTypeRequiredDefaultDescription
namestringYes-Unique subscription name
brokerstringYes-Broker URL (tcp://, ssl://, ws://)
topicsarrayYes-Topics to subscribe
databasestringYes-Target Arc database
qosintNo1QoS level: 0, 1, or 2
client_idstringNoautoMQTT client ID
usernamestringNo-MQTT username
passwordstringNo-MQTT password (encrypted at rest)
tls_enabledboolNofalseEnable TLS/SSL
tls_cert_pathstringNo-Client certificate path
tls_key_pathstringNo-Client key path
tls_ca_pathstringNo-CA certificate path
topic_mappingobjectNoTopic-to-measurement mapping
auto_startboolNotrueStart on creation and server restart

GET /api/v1/mqtt/subscriptions​

List all MQTT subscriptions.

Response:

{
  "subscriptions": [
    {
      "id": "sub_abc123",
      "name": "factory-sensors",
      "broker": "tcp://localhost:1883",
      "status": "running"
    }
  ],
  "count": 1
}

GET /api/v1/mqtt/subscriptions/:id​

Get subscription details.

PUT /api/v1/mqtt/subscriptions/:id​

Update a subscription. Subscription must be stopped first.

DELETE /api/v1/mqtt/subscriptions/:id​

Delete a subscription. Subscription must be stopped first.

POST /api/v1/mqtt/subscriptions/:id/start​

Start a stopped subscription.

Response:

{
  "id": "sub_abc123",
  "status": "running",
  "message": "Subscription started"
}

POST /api/v1/mqtt/subscriptions/:id/stop​

Stop a running subscription.

POST /api/v1/mqtt/subscriptions/:id/restart​

Restart a subscription (stop + start).

GET /api/v1/mqtt/subscriptions/:id/stats​

Get statistics for a specific subscription.

Response:

{
  "id": "sub_abc123",
  "messages_received": 15420,
  "bytes_received": 2458320,
  "decode_errors": 0,
  "last_message_at": "2026-02-01T10:30:15Z",
  "topics": {
    "sensors/temperature": 8500,
    "sensors/humidity": 6920
  }
}

GET /api/v1/mqtt/stats​

Aggregate statistics across all running subscriptions.

Response:

{
  "status": "success",
  "running_count": 2,
  "subscriptions_stats": {
    "sub_abc123": { ... },
    "sub_def456": { ... }
  }
}

GET /api/v1/mqtt/health​

MQTT service health check.

Response:

{
  "status": "healthy",
  "healthy": true,
  "running_count": 2,
  "connected_count": 2,
  "disconnected_count": 0,
  "service": "mqtt_subscriptions"
}

Response Formats​

Success Response​

{
  "status": "success",
  "data": [...],
  "count": 10
}

Error Response​

{
  "error": "Error message"
}

HTTP Status Codes​

  • 200 - Success
  • 204 - No Content (successful write)
  • 400 - Bad Request
  • 401 - Unauthorized
  • 403 - Forbidden (requires admin)
  • 404 - Not Found
  • 500 - Internal Server Error

Rate Limiting​

Arc does not enforce rate limiting by default. For production deployments, consider:

  • Reverse proxy rate limiting (Nginx, Traefik)
  • API Gateway (AWS API Gateway, Kong)
  • Application-level throttling

CORS​

CORS is enabled by default with permissive settings. Configure via reverse proxy for production.

Best Practices​

1. Use MessagePack for Writes​

MessagePack is 5x faster than Line Protocol:

# Fast: MessagePack columnar
data = {"m": "cpu", "columns": {...}}
requests.post(url, data=msgpack.packb(data))

# Slower: Line Protocol text
data = "cpu,host=server01 usage=45.2"
requests.post(url, data=data)

2. Batch Your Writes​

Send multiple records per request:

# Good: Batch write
data = {
    "m": "cpu",
    "columns": {
        "time": [t1, t2, t3, ...],
        "host": [h1, h2, h3, ...],
        "usage": [u1, u2, u3, ...]
    }
}

3. Use Arrow for Large Queries​

For 10K+ rows, use the Arrow endpoint:

response = requests.post(url + "/api/v1/query/arrow", ...)
table = pa.ipc.open_stream(response.content).read_all()
df = table.to_pandas()  # Zero-copy conversion

4. Enable Gzip Compression​

import gzip

compressed = gzip.compress(msgpack.packb(data))
requests.post(
    url,
    data=compressed,
    headers={"Content-Encoding": "gzip", ...}
)

Client Libraries​

Python (Official SDK)​

pip install arc-tsdb-client[all]
from arc_client import ArcClient

with ArcClient(host="localhost", token="your-token") as client:
    client.write.write_columnar(
        measurement="cpu",
        columns={"time": [...], "host": [...], "usage": [...]},
    )
    df = client.query.query_pandas("SELECT * FROM default.cpu LIMIT 10")

See Python SDK Documentation for full details.

Next Steps​