Java client

QuestDB Java client for high-performance data ingestion

The QuestDB Java client provides a high-performance API for ingesting data using the InfluxDB Line Protocol.

Installation

Maven

<dependency>
    <groupId>org.questdb</groupId>
    <artifactId>questdb</artifactId>
    <version>9.3.3</version>
</dependency>

Quick start

import io.questdb.client.Sender;
import java.time.Instant;

public class Example {
    public static void main(String[] args) {
        try (Sender sender = Sender.builder()
                .address("localhost:9009")
                .build()) {
            
            sender.table("trades")
                .symbol("symbol", "ETH-USD")
                .symbol("side", "sell")
                .doubleColumn("price", 2615.54)
                .doubleColumn("amount", 0.00044)
                .atNow();
            
            sender.flush();
        }
    }
}

Configuration

Sender sender = Sender.builder()
    .address("localhost:9009")
    .enableAuth("admin")
    .authToken("your-token")
    .bufferCapacity(128 * 1024)  // 128KB
    .build();

Builder options

address · string · required

Server address in format host:port

bufferCapacity · int

Buffer size in bytes (default: 64KB)

enableAuth · string

Enable authentication with key ID

authToken · string

Authentication token (private key)

Data types

sender.table("sensors")
    .symbol("location", "warehouse-1")           // Symbol
    .longColumn("sensor_id", 12345)              // Long
    .doubleColumn("temperature", 23.5)           // Double
    .stringColumn("status", "active")            // String
    .booleanColumn("is_online", true)            // Boolean
    .timestampColumn("timestamp", Instant.now()) // Timestamp
    .atNow();  // Use server timestamp

Best practices

Use try-with-resources to ensure proper cleanup of sender resources.

try (Sender sender = Sender.builder().address("localhost:9009").build()) {
    // Batch multiple rows
    for (int i = 0; i < 1000; i++) {
        sender.table("metrics")
            .symbol("host", "server-" + i)
            .doubleColumn("cpu", Math.random() * 100)
            .atNow();
    }
    sender.flush();
}

Error handling

try (Sender sender = Sender.builder().address("localhost:9009").build()) {
    sender.table("trades")
        .symbol("symbol", "BTC-USD")
        .doubleColumn("price", 50000.0)
        .atNow();
    sender.flush();
} catch (Exception e) {
    System.err.println("Failed to send data: " + e.getMessage());
}

Performance tips

1. Batch rows: Send multiple rows before calling flush()
2. Reuse sender: Create once, use for entire application lifecycle
3. Use symbols: Convert low-cardinality strings to symbols
4. Async flush: Consider implementing async flushing for higher throughput

Next steps

ILP Reference

Learn more about the protocol

Examples

Browse code examples