Clusters

Configure the nodes

• All ClickHouse nodes must have the same database name, user name and password.

• Reads and writes go to the first node that answers.

• Migrations run on all nodes. If a node does not answer, the migration throws.

• ReplicatedMergeTree uses the {replica} and {shard} macros. Define them in the configuration of each ClickHouse server, in config.xml or config.d/*.xml, not in this package:

  <macros>
      <shard>01</shard>
      <replica>clickhouse01</replica>
  </macros>

  See tests/docker/clickhouse01/config.xml in the repository, or the ClickHouse macros.

Give the nodes in cluster:

'clickhouse' => [
    'driver' => 'clickhouse',
    'cluster' => [
        ['host' => 'clickhouse01', 'port' => '8123'],
        ['host' => 'clickhouse02', 'port' => '8123'],
    ],
    // Optional. Migration::createMergeTree() adds ON CLUSTER '<name>'.
    'cluster_name' => 'company_cluster',
    'database' => env('CLICKHOUSE_DATABASE', 'default'),
    'username' => env('CLICKHOUSE_USERNAME', 'default'),
    'password' => env('CLICKHOUSE_PASSWORD', ''),
    'timeout_connect' => env('CLICKHOUSE_TIMEOUT_CONNECT', 2),
    'timeout_query' => env('CLICKHOUSE_TIMEOUT_QUERY', 2),
    'https' => (bool) env('CLICKHOUSE_HTTPS', null),
    'retries' => env('CLICKHOUSE_RETRIES', 0),
    'settings' => [ // Optional
        'max_partitions_per_insert_block' => 300,
    ],
    'fix_default_query_builder' => true,
],

cluster_name must be a cluster of the server configuration (remote_servers).

ON CLUSTER

With cluster_name, createMergeTree() adds ON CLUSTER '<cluster_name>'. Then add ->ifNotExists():

static::createMergeTree('my_table', fn(MergeTree $table) => $table
    ->ifNotExists()
    ->columns([...])
    ->orderBy('id')
);

The package sends a migration to each node in turn. ON CLUSTER creates the table on all nodes at the first node. Without IF NOT EXISTS, the statement of the second node fails with TABLE_ALREADY_EXISTS.

Without cluster_name, each node creates the table, because the migration goes to each node.

Replicated tables

return new class extends \Oralunal\LaravelClickHouse\Migration
{
    public function up()
    {
        static::write("
            CREATE TABLE my_table (
                id UInt32,
                created_at DateTime,
                field_one String,
                field_two Int32
            )
            ENGINE = ReplicatedMergeTree('/clickhouse/tables/default.my_table', '{replica}')
            ORDER BY (id)
        ");
    }

    public function down()
    {
        static::write('DROP TABLE my_table');
    }
};

Change the active node

$row = new MyTable();
echo $row->getThisClient()->getConnectHost();
// clickhouse01
$row->resolveConnection()->getCluster()->slideNode();
echo $row->getThisClient()->getConnectHost();
// clickhouse02

On 3.x, slideNode() stays on the current node when the next node does not answer. On a cluster of three or more nodes, it does not reach the nodes after a node that is down. 4.0 tries the next nodes in turn.