README.md

ClickHouse C++ client

C++ client for ClickHouse.

Supported data types

• Array(T)
• Date
• DateTime, DateTime64
• DateTime([timezone]), DateTime64(N, [timezone])
• Decimal32, Decimal64, Decimal128
• Enum8, Enum16
• FixedString(N)
• Float32, Float64
• IPv4, IPv6
• Nullable(T)
• String
• LowCardinality(String) or LowCardinality(FixedString(N))
• Tuple
• UInt8, UInt16, UInt32, UInt64, Int8, Int16, Int32, Int64
• Int128
• UUID

Building

$ mkdir build .
$ cd build
$ cmake .. [-DBUILD_TESTS=ON]
$ make

Example

#include <clickhouse/client.h>

using namespace clickhouse;

/// Initialize client connection.
Client client(ClientOptions().SetHost("localhost"));

/// Create a table.
client.Execute("CREATE TABLE IF NOT EXISTS test.numbers (id UInt64, name String) ENGINE = Memory");

/// Insert some values.
{
    Block block;

    auto id = std::make_shared<ColumnUInt64>();
    id->Append(1);
    id->Append(7);

    auto name = std::make_shared<ColumnString>();
    name->Append("one");
    name->Append("seven");

    block.AppendColumn("id"  , id);
    block.AppendColumn("name", name);

    client.Insert("test.numbers", block);
}

/// Select values inserted in the previous step.
client.Select("SELECT id, name FROM test.numbers", [] (const Block& block)
    {
        for (size_t i = 0; i < block.GetRowCount(); ++i) {
            std::cout << block[0]->As<ColumnUInt64>()->At(i) << " "
                      << block[1]->As<ColumnString>()->At(i) << "\n";
        }
    }
);

/// Delete table.
client.Execute("DROP TABLE test.numbers");

Please note that Client instance is NOT thread-safe. I.e. you must create a separate Client for each thread or utilize some synchronization techniques.

Features

Multiple host

It is possible to specify multiple hosts to connect to. The connection will be set to the first available host.

Client client(ClientOptions()
              .SetHost({
                  {"host1.com", 8000},
                  {"host2.com"}, /// port is ClientOptions.port
              }));