Class: ChConnect::Connection

Inherits:
Object
  • Object
show all
Defined in:
lib/ch_connect/connection.rb

Overview

A pooled ClickHouse connection built on the clickhouse-c ioless client: the C extension is a pure protocol state machine + block decoder, and all socket I/O, TLS, and timeouts live here in Ruby. Result blocks are parsed in C.

Maintains a pool of connections (config.pool_size); the native protocol handles one query at a time per connection, so concurrent queries each check out their own connection.

Constant Summary collapse

COMPRESSION_AVAILABLE = 
{
  nil => true,
  :lz4 => NativeClient::LZ4_AVAILABLE,
  :zstd => NativeClient::ZSTD_AVAILABLE
}.freeze
READ_CHUNK = 
64 * 1024
WRITE_CHUNK = 
64 * 1024
PARAM_ESCAPES = 
{
  "\0" => "\\0", "\a" => "\\a", "\b" => "\\b", "\e" => "\\e",
  "\f" => "\\f", "\n" => "\\n", "\r" => "\\r", "\t" => "\\t",
  "\v" => "\\v", "'" => "\\'", "\\" => "\\\\"
}.freeze
PARAM_ESCAPE_PATTERN = 
/[\0\a\b\e\f\n\r\t\v'\\]/
RESERVED_SETTINGS = 
{
  "network_compression_method" => "set config.compression instead",
  "output_format_native_encode_types_in_binary_format" => "required by the native decoder"
}.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config = ChConnect.config) ⇒ Connection

Creates a new connection.

Parameters:

  • config (Config) (defaults to: ChConnect.config) —

    configuration instance (defaults to global config)



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# File 'lib/ch_connect/connection.rb', line 237

def initialize(config = ChConnect.config)
  @config = config.dup.freeze
  validate_compression!
  @codec_name = @config.compression&.to_s
  @pool = ConnectionPool.new(
    size: @config.pool_size,
    timeout: @config.pool_timeout,
    auto_reload_after_fork: true
  ) do
    Slot.new(@config)
  end
end

Instance Attribute Details

#config ⇒ Config (readonly)

Returns the configuration used by this connection.

Returns:

  • (Config) —

    the configuration used by this connection



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# File 'lib/ch_connect/connection.rb', line 232

def config
  @config
end

Instance Method Details

#close ⇒ void

This method returns an undefined value.

Closes all pooled connections.



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# File 'lib/ch_connect/connection.rb', line 269

def close
  @pool.shutdown(&:close)
end

#query(sql, params: nil, settings: nil, idempotent: false) ⇒ Response

Executes and instruments a SQL query.

Parameters:

  • sql (String) —

    SQL query to execute

  • params (Hash, nil) (defaults to: nil) —

    query parameters (name => value)

  • settings (Hash, nil) (defaults to: nil) —

    per-query ClickHouse settings

  • idempotent (Boolean) (defaults to: false) —

    retry transport failures on a fresh connection up to config.max_retries (default: false)

Returns:

Raises:



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# File 'lib/ch_connect/connection.rb', line 260

def query(sql, params: nil, settings: nil, idempotent: false)
  @config.instrumenter.instrument("query.clickhouse", {sql: sql}) do
    execute_query(sql, params, settings, idempotent)
  end
end