QuestDB Integration Guide

Connect to QuestDB databases to query time-series data in your pipelines. This guide walks you through everything from basic setup to advanced configurations.

Overview

The QuestDB connector is your gateway to high-performance time-series database operations in MaestroHub. It enables you to:

• Query data from tables using standard SQL with QuestDB extensions
• Use parameterized queries for dynamic, reusable data operations
• Leverage time-series features like SAMPLE BY, LATEST ON, and ASOF JOIN
• Secure connections with SSL/TLS encryption (QuestDB Enterprise)

PostgreSQL Wire Protocol

QuestDB exposes a PostgreSQL wire protocol (pgwire) endpoint on port 8812 by default. The MaestroHub connector uses the same pgx driver as PostgreSQL, ensuring full compatibility with QuestDB's SQL engine.

Connection Configuration

Creating a QuestDB Connection

Navigate to Connections → New Connection → QuestDB and configure the following:

QuestDB Connection Creation Fields

1. Profile Information

Field	Default	Description
Profile Name	-	A descriptive name for this connection profile (required, max 100 characters)
Description	-	Optional description for this QuestDB connection

2. Database Configuration

Field	Default	Description
Host	localhost	QuestDB server hostname or IP address - required
Port	8812	QuestDB PostgreSQL wire protocol port (1-65535) - required
Connect Timeout (sec)	30	Maximum time to wait for connection establishment (0-600 seconds) - required
Database	qdb	Database name to connect to - required

Default Port

QuestDB uses port 8812 for its pgwire endpoint, not the standard PostgreSQL port 5432. Make sure your firewall allows traffic on this port.

3. Basic Authentication

Field	Default	Description
Username	admin	QuestDB database user (required)
Password	-	QuestDB user password

4. SSL Settings

4a. SSL Configuration

Field	Default	Description
Enable SSL	false	Use encrypted connection to QuestDB server

4b. SSL Mode

(Only displayed when SSL is enabled)

When SSL is enabled, the connection uses sslmode=require which encrypts the connection without verifying the server certificate.

QuestDB SSL Support

• QuestDB Open Source does not support native TLS on the pgwire endpoint. Use a TLS-terminating proxy like PgBouncer for encrypted connections.
• QuestDB Enterprise supports native TLS on all protocols including pgwire.

5. Connection Pool Settings

Field	Default	Description
Max Open Connections	100	Maximum number of simultaneous database connections (0-1000). Higher values increase concurrency but add DB load
Max Idle Connections	25	Idle connections kept ready for reuse to reduce latency (0-1000, 0 = close idle connections immediately)
Connection Max Lifetime (sec)	900	Maximum age of a connection before it is recycled (0-86400 seconds, 0 = keep connections indefinitely). Helpful to avoid server-side timeouts
Connection Max Idle Time (sec)	300	How long an idle connection may remain unused before being closed (0-86400 seconds, 0 = disable idle timeout)

Connection pool settings help optimize database performance by balancing concurrency, resource usage, and latency across workloads.

6. Retry Configuration

Field	Default	Description
Retries	3	Number of connection attempts (0-10, 0 = no retry)
Retry Delay (ms)	100	Delay between retry attempts in milliseconds (0-3600000 ms)
Retry Backoff Multiplier	2	Exponential factor for retry delay growth (1-10, e.g., 2.0 means each retry waits twice as long)

Example Retry Behavior

• With Retry Delay = 100ms and Retry Backoff Multiplier = 2:
  • 1st retry: wait 100ms
  • 2nd retry: wait 200ms
  • 3rd retry: wait 400ms

7. Connection Labels

Field	Default	Description
Labels	-	Key-value pairs to categorize and organize this QuestDB connection (max 10 labels)

Example Labels

• env: prod - Environment
• team: data - Responsible team

Notes

• Required Fields: All fields described as "required" must be filled.
• SSL/TLS: When SSL is disabled, SSL Mode is automatically set to disable. Native TLS requires QuestDB Enterprise or a TLS proxy.
• Connection Pooling: Manages concurrency with Max Open Connections, reduces latency with Max Idle Connections, mitigates stale connections via Connection Max Lifetime, and frees resources using Connection Max Idle Time.
• Retry Logic: Implements exponential backoff; initial connection attempts use the base delay and each retry multiplies the delay by the backoff factor. Ideal for transient network issues or database restarts.
• Timeout Values: Connect Timeout applies to initial connection establishment; all timeout values are in seconds unless noted (Retry Delay uses milliseconds).

Function Builder

Creating QuestDB Functions

Once you have a connection established, you can create reusable query functions:

1. Navigate to Functions → New Function
2. Select QuestDB Query as the function type
3. Choose your QuestDB connection
4. Write your SQL query with parameters

QuestDB query function creation interface with SQL editor and parameter configuration

Query Function

Purpose: Execute SQL statements on QuestDB. Run standard SQL queries enhanced with QuestDB's time-series extensions to read data from your time-series database.

Configuration Fields

Field	Type	Required	Default	Description
SQL Query	String	Yes	-	SQL statement to execute (SELECT). Supports parameterized queries with QuestDB SQL extensions.
Timeout (seconds)	Number	No	10	Per-execution timeout in seconds. Sets maximum time allowed for query execution.

Use Cases:

• SELECT sensor readings with time-based filtering
• Aggregate metrics using SAMPLE BY for downsampling
• Retrieve latest values per device using LATEST ON
• Perform time-series joins with ASOF JOIN

Using Parameters

The ((parameterName)) syntax creates dynamic, reusable queries. Parameters are automatically detected and can be configured with:

Configuration	Description	Example
Type	Data type validation	string, number, boolean, date, array
Required	Make parameters mandatory or optional	Required / Optional
Default Value	Fallback value if not provided	NOW(), 0, active
Description	Help text for users	"Start date for the report"

Parameter configuration interface showing type validation, required flags, default values, and descriptions

Pipeline Integration

Use the QuestDB query functions you create here as nodes inside the Pipeline Designer to query time-series data alongside the rest of your operations stack. Drag the query node onto the canvas, bind its parameters to upstream outputs or constants, and configure connection-level options without leaving the designer.

For end-to-end orchestration ideas, such as combining database reads with MQTT, REST, or analytics steps, explore the Connector Nodes page to see how SQL nodes complement other automation patterns.

QuestDB query node in the pipeline designer with connection, function, and parameter configuration

Common Use Cases

Real-Time Sensor Monitoring

Scenario: Query the latest sensor readings across all devices.

SELECT * FROM sensors
LATEST ON timestamp PARTITION BY sensor_id
WHERE timestamp > dateadd('h', -1, now());

Pipeline Integration: Use in a pipeline to feed real-time dashboards or trigger alerts based on threshold breaches.

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Time-Series Downsampling

Scenario: Generate hourly averages of sensor data for reporting.

SELECT
    timestamp,
    sensor_id,
    avg(temperature) as avg_temp,
    avg(pressure) as avg_pressure,
    min(temperature) as min_temp,
    max(temperature) as max_temp
FROM sensors
WHERE timestamp BETWEEN ((startDate)) AND ((endDate))
SAMPLE BY 1h
ALIGN TO CALENDAR;

Pipeline Integration: Schedule this function to run periodically and push aggregated data to BI tools, dashboards, or downstream databases.

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Cross-Stream Time-Series Joins

Scenario: Correlate temperature readings with production events using time-based joins.

SELECT
    t.timestamp,
    t.sensor_id,
    t.temperature,
    p.event_type,
    p.machine_id
FROM sensors t
ASOF JOIN production_events p ON (t.sensor_id = p.sensor_id)
WHERE t.timestamp > dateadd('d', -1, now());

Pipeline Integration: Combine with data transformation nodes to enrich sensor data with production context for analytics.

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Data Retention Queries

Scenario: Query data within a retention window for archiving or cleanup workflows.

SELECT count(*) as record_count,
    min(timestamp) as oldest_record,
    max(timestamp) as newest_record
FROM sensors
WHERE timestamp < dateadd('d', -((retentionDays)), now());

Pipeline Integration: Schedule this function to run daily or weekly via pipeline triggers (cron jobs) to monitor data retention.