Class: RBHive::TCLIConnection

Inherits:
Object
  • Object
show all
Defined in:
lib/rbhive/t_c_l_i_connection.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(server, port = 10_000, options = {}, logger = StdOutLogger.new) ⇒ TCLIConnection

Returns a new instance of TCLIConnection.



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 73

def initialize(server, port=10_000, options={}, logger=StdOutLogger.new)
  options ||= {} # backwards compatibility
  raise "'options' parameter must be a hash" unless options.is_a?(Hash)
  
  if options[:transport] == :sasl and options[:sasl_params].nil?
    raise ":transport is set to :sasl, but no :sasl_params option was supplied"
  end
  
  # Defaults to buffered transport, Hive 0.10, 1800 second timeout
  options[:transport]     ||= :buffered
  options[:hive_version]  ||= 10
  options[:timeout]       ||= 1800
  @options = options
  
  # Look up the appropriate Thrift protocol version for the supplied Hive version
  @thrift_protocol_version = thrift_hive_protocol(options[:hive_version])
  
  @logger = logger
  @transport = thrift_transport(server, port)
  @protocol = Thrift::BinaryProtocol.new(@transport)
  @client = Hive2::Thrift::TCLIService::Client.new(@protocol)
  @session = nil
  @logger.info("Connecting to HiveServer2 #{server} on port #{port}")
  @mutex = Mutex.new
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(meth, *args) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 262

def method_missing(meth, *args)
  client.send(meth, *args)
end

Instance Attribute Details

#client ⇒ Object (readonly)

Returns the value of attribute client.



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 71

def client
  @client
end

Instance Method Details

#add_columns(schema) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 258

def add_columns(schema)
  execute(schema.add_columns_statement)
end

#close ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 140

def close
  @transport.close
end

#close_session ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 148

def close_session
  @client.CloseSession prepare_close_session
  @session = nil
end

#create_table(schema) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 245

def create_table(schema)
  execute(schema.create_table_statement)
end

#drop_table(name) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 249

def drop_table(name)
  name = name.name if name.is_a?(TableSchema)
  execute("DROP TABLE `#{name}`")
end

#execute(query) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 161

def execute(query)
  execute_safe(query)
end

#explain(query) ⇒ Object

Performs a explain on the supplied query on the server, returns it as a ExplainResult. (Only works on 0.12 if you have this patch - issues.apache.org/jira/browse/HIVE-5492)



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 180

def explain(query)
  rows = []
  fetch_in_batch("EXPLAIN " + query) do |batch|
    rows << batch.map { |b| b[:Explain] }
  end
  ExplainResult.new(rows.flatten)
end

#fetch(query, max_rows = 100) ⇒ Object

Performs a query on the server, fetches up to max_rows rows and returns them as an array.



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 189

def fetch(query, max_rows = 100)
  safe do
    # Execute the query and check the result
    exec_result = execute_unsafe(query)
    raise_error_if_failed!(exec_result)

    # Get search operation handle to fetch the results
    op_handle = exec_result.operationHandle

    # Prepare and execute fetch results request
    fetch_req = prepare_fetch_results(op_handle, :first, max_rows)
    fetch_results = client.FetchResults(fetch_req)
    raise_error_if_failed!(fetch_results)

    # Get data rows and format the result
    rows = fetch_results.results.rows
    the_schema = TCLISchemaDefinition.new(get_schema_for( op_handle ), rows.first)
    TCLIResultSet.new(rows, the_schema)
  end
end

#fetch_in_batch(query, batch_size = 1000, &block) ⇒ Object

Performs a query on the server, fetches the results in batches of batch_size rows and yields the result batches to a given block as arrays of rows.



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 212

def fetch_in_batch(query, batch_size = 1000, &block)
  raise "No block given for the batch fetch request!" unless block_given?
  safe do
    # Execute the query and check the result
    exec_result = execute_unsafe(query)
    raise_error_if_failed!(exec_result)

    # Get search operation handle to fetch the results
    op_handle = exec_result.operationHandle

    # Prepare fetch results request
    fetch_req = prepare_fetch_results(op_handle, :next, batch_size)

    # Now let's iterate over the results
    loop do
      # Fetch next batch and raise an exception if it failed
      fetch_results = client.FetchResults(fetch_req)
      raise_error_if_failed!(fetch_results)

      # Get data rows from the result
      rows = fetch_results.results.rows
      break if rows.empty?

      # Prepare schema definition for the row
      schema_for_req ||= get_schema_for(op_handle)
      the_schema ||= TCLISchemaDefinition.new(schema_for_req, rows.first)

      # Format the results and yield them to the given block
      yield TCLIResultSet.new(rows, the_schema)
    end
  end
end

#open ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 136

def open
  @transport.open
end

#open_session ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 144

def open_session
  @session = @client.OpenSession(prepare_open_session(@thrift_protocol_version))
end

#parse_sasl_params(sasl_params) ⇒ Object

Processes SASL connection params and returns a hash with symbol keys or a nil



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 125

def parse_sasl_params(sasl_params)
  # Symbilize keys in a hash
  if sasl_params.kind_of?(Hash)
    return sasl_params.inject({}) do |memo,(k,v)|
      memo[k.to_sym] = v;
      memo
    end
  end
  return nil
end

#priority=(priority) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 165

def priority=(priority)
  set("mapred.job.priority", priority)
end

#queue=(queue) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 169

def queue=(queue)
  set("mapred.job.queue.name", queue)
end

#replace_columns(schema) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 254

def replace_columns(schema)
  execute(schema.replace_columns_statement)
end

#session ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 153

def session
  @session && @session.sessionHandle
end

#set(name, value) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 173

def set(name,value)
  @logger.info("Setting #{name}=#{value}")
  self.execute("SET #{name}=#{value}")
end

#thrift_hive_protocol(version) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 99

def thrift_hive_protocol(version)
  HIVE_THRIFT_MAPPING[version] || raise("Invalid Hive version")
end

#thrift_socket(server, port, timeout) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 118

def thrift_socket(server, port, timeout)
  socket = Thrift::Socket.new(server, port)
  socket.timeout = timeout
  socket
end

#thrift_transport(server, port) ⇒ Object 



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# File 'lib/rbhive/t_c_l_i_connection.rb', line 103

def thrift_transport(server, port)
  @logger.info("Initializing transport #{@options[:transport]}")
  case @options[:transport]
  when :buffered
    return Thrift::BufferedTransport.new(thrift_socket(server, port, @options[:timeout]))
  when :sasl
    return Thrift::SaslClientTransport.new(thrift_socket(server, port, @options[:timeout]),
                                           parse_sasl_params(@options[:sasl_params]))
  when :http
    return Thrift::HTTPClientTransport.new("http://#{server}:#{port}/cliservice")
  else
    raise "Unrecognised transport type '#{transport}'"
  end
end