C & C++ Client Documentation

QuestDB supports the C & C++ programming languages, providing a high-performance ingestion client tailored for insert-only operations. This integration ensures peak efficiency in time series data ingestion and analysis, perfectly suited for systems for systems which require top performance and minimal latency.

Key features of the QuestDB C & C++ client include:

  • Automatic table creation: No need to define your schema upfront.
  • Concurrent schema changes: Seamlessly handle multiple data streams with on-the-fly schema modifications
  • Optimized batching: Use strong defaults or curate the size of your batches
  • Health checks and feedback: Ensure your system's integrity with built-in health monitoring
  • Automatic write retries: Reuse connections and retry after interruptions

This guide aims to help you swiftly set up and begin using the QuestDB C++ client.

C++​

C++
Documentation iconView full docsGithub iconView source code

Explore the full capabilities of the C++ client via the C++ README.

Requirements​

  • Requires a C++ compiler and standard libraries.
  • Assumes QuestDB is running. If it's not, refer to the general quick start.

Client Installation​

Clone the GitHub repository and compile the source code:

git clone https://github.com/questdb/c-questdb-client.git
cd c-questdb-client
make

This will compile the client library, which can then be linked to your C++ projects.

Connection​

The QuestDB C client supports basic connection and authentication configurations.

Here is an example of how to configure and use the client for data ingestion:

#include <questdb/ingress/line_sender.hpp>

...

auto sender = questdb::ingress::line_sender::from_conf(
    "http::addr=localhost:9000;");

Basic data insertion​

questdb::ingress::line_sender_buffer buffer;
buffer
    .table("cpp_cars")
    .symbol("id", "d6e5fe92-d19f-482a-a97a-c105f547f721")
    .column("x", 30.5)
    .at(timestamp_nanos::now());

// To insert more records, call `buffer.table(..)...` again.

sender.flush(buffer);

C​

C
Documentation iconView full docsGithub iconView source code

Explore the full capabilities of the C client via the C README.

Requirements​

  • Requires a C compiler and standard libraries.
  • Assumes QuestDB is running. If it's not, refer to the general quick start.

Client Installation​

Clone the GitHub repository and compile the source code:

git clone https://github.com/questdb/c-questdb-client.git
cd c-questdb-client
make

This will compile the client library, which can then be linked to your C projects.

Connection​

The QuestDB C client supports basic connection and authentication configurations. Here is an example of how to configure and use the client for data ingestion:

#include <questdb/ingress/line_sender.h>

...

line_sender_utf8 conf = QDB_UTF8_LITERAL(
    "http::addr=localhost:9000;");

line_sender_error* err = NULL;
line_sender* sender = sender = line_sender_from_conf(&err);
if (!sender) {
    /* ... handle error ... */
}

Basic data insertion​

line_sender_table_name table_name = QDB_TABLE_NAME_LITERAL("c_cars");
line_sender_column_name id_name = QDB_COLUMN_NAME_LITERAL("id");
line_sender_column_name x_name = QDB_COLUMN_NAME_LITERAL("x");

line_sender_buffer* buffer = line_sender_buffer_new();

if (!line_sender_buffer_table(buffer, table_name, &err))
    goto on_error;

line_sender_utf8 id_value = QDB_UTF8_LITERAL(
    "d6e5fe92-d19f-482a-a97a-c105f547f721");
if (!line_sender_buffer_symbol(buffer, id_name, id_value, &err))
    goto on_error;

if (!line_sender_buffer_column_f64(buffer, x_name, 30.5, &err))
    goto on_error;

if (!line_sender_buffer_at_nanos(buffer, line_sender_now_nanos(), &err))
    goto on_error;

// To insert more records, call `line_sender_buffer_table(..)...` again.

if (!line_sender_flush(sender, buffer, &err))
    goto on_error;

line_sender_close(sender);

Health check​

To monitor your active connection, there is a ping endpoint:

curl -I http://localhost:9000/ping

Returns (pong!):

HTTP/1.1 204 OK
Server: questDB/1.0
Date: Fri, 2 Feb 2024 17:09:38 GMT
Transfer-Encoding: chunked
Content-Type: text/plain; charset=utf-8
X-Influxdb-Version: v2.7.4

Determine whether an instance is active and confirm the version of InfluxDB Line Protocol with which you are interacting.

Next Steps​

With data flowing into QuestDB, now it's time to for analysis.

To learn The Way of QuestDB SQL, see the Query & SQL Overview.

Alone? Stuck? Want help? Visit us in our Community Forum.