CPP.md

Getting Started with C++

Building and depending on this library

• To begin with, we suggest first building the library to ensure you have all the tooling and build dependencies set up just right by following the build instructions
• Then read the guide for including this library as a dependency from your project.

Complete Examples

• Basic example in C++.
• With authentication.
• With authentication and TLS.
• Custom certificate authority file.

API Overview

Header

• .hpp header file

Connnecting

#include <questdb/ingress/line_sender.hpp>

...

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

See the main client libraries documentation for the full config string params, including authentication, tls, etc.

You can also connect programmatically using the questdb::ingress::opts object.

Building Messages

The line_sender object is responsible for connecting to the network and sending data.

Use the line_sender_buffer type to construct messages (aka rows, aka records, aka lines).

To avoid malformed messages, the line_sender_buffer object's methods must be called in a specific order.

For each row, you need to specify a table name and at least one symbol or column. Symbols must be specified before columns.

You can accumulate multiple lines (rows) with a given buffer and a buffer is re-usable, but a buffer may only be flushed via the sender after a call to buffer.at(..) (preferred) or buffer.at_now().

questdb::ingress::line_sender_buffer buffer;
buffer
    .table("trades")
    .symbol("symbol", "ETH-USD")
    .column("price", 2615.54)
    .at(timestamp_nanos::now());

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

sender.flush(buffer);

Diagram of valid call order of the buffer API.

Error handling

Note that most methods in C++ may throw questdb::ingress::line_sender_error exceptions. The C++ line_sender_error type inherits from std::runtime_error and you can obtain an error message description by calling .what() and an error code calling .code().

Further Topics

• Data quality and threading considerations
• Authentication and TLS encryption