Class: Vertica::Query

Inherits:
Object
  • Object
show all
Defined in:
lib/vertica/query.rb

Overview

Note:

This class is for internal use only, you should never interact with this class directly.

The Query class handles the state of the connection while a SQL query is being executed. The connection should call #run and it will block until the query has been handled by the connection, after which control will be given back to the Connection instance.

See Also:

Instance Method Summary collapse

Constructor Details

#initialize(connection, sql, row_handler: nil, copy_handler: nil) ⇒ Query

Instantiates a new query

Parameters:

  • connection (Vertica::Connection) —

    The connection to use for the query

  • sql (String) —

    The SQL statement to execute.

  • row_handler (Proc, nil) (defaults to: nil) —

    Callback that will be called for every row that is returned. If no handler is provided, all rows will be buffered so a Result can be returned.

  • copy_handler (Proc, nil) (defaults to: nil) —

    Callback that will be called when the connection is ready to receive data for a COPY ... FROM STDIN statement.



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# File 'lib/vertica/query.rb', line 19

def initialize(connection, sql, row_handler: nil, copy_handler: nil)
  @connection, @sql = connection, sql
  @buffer = row_handler.nil? && copy_handler.nil? ? [] : nil
  @row_handler = row_handler || lambda { |row| buffer_row(row) }
  @copy_handler = copy_handler
  @row_description, @error = nil, nil
end

Instance Method Details

#inspect ⇒ String

Returns a user-consumable string representation of this query instance.

Returns:

  • (String) —

    Returns a user-consumable string representation of this query instance.



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# File 'lib/vertica/query.rb', line 46

def inspect
  "#<Vertica::Query:#{object_id} sql=#{@sql.inspect}>"
end

#run ⇒ String, Vertica::Result

Sends the query to the server, and processes the results.

Returns:

  • (String) —

    For an unbuffered query, the type of SQL command will be return as a string (e.g. "SELECT" or "COPY").

  • (Vertica::Result) —

    For a buffered query, this method will return a Result instance

Raises:



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# File 'lib/vertica/query.rb', line 34

def run
  @connection.write_message(Vertica::Protocol::Query.new(@sql))

  begin
    process_message(message = @connection.read_message)
  end until message.kind_of?(Vertica::Protocol::ReadyForQuery)

  raise @error unless @error.nil?
  return @result
end