Class: BigShift::RedshiftUnloader

Inherits:
Object
  • Object
show all
Defined in:
lib/bigshift/redshift_unloader.rb

Instance Method Summary collapse

Constructor Details

#initialize(redshift_connection, aws_credentials, options = {}) ⇒ RedshiftUnloader

Returns a new instance of RedshiftUnloader.



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# File 'lib/bigshift/redshift_unloader.rb', line 3

def initialize(redshift_connection, aws_credentials, options={})
  @redshift_connection = redshift_connection
  @aws_credentials = aws_credentials
  @logger = options[:logger] || NullLogger::INSTANCE
end

Instance Method Details

#unload_to(table_name, s3_uri, options = {}) ⇒ Object 



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# File 'lib/bigshift/redshift_unloader.rb', line 9

def unload_to(table_name, s3_uri, options={})
  table_schema = RedshiftTableSchema.new(table_name, @redshift_connection)
  credentials_string = "aws_access_key_id=#{@aws_credentials.access_key_id};aws_secret_access_key=#{@aws_credentials.secret_access_key}"
  select_sql = 'SELECT '
  select_sql << table_schema.columns.map(&:to_sql).join(', ')
  select_sql << %Q< FROM "#{table_name}">
  select_sql.gsub!('\'') { |s| '\\\'' }
  unload_sql = %Q<UNLOAD ('#{select_sql}')>
  unload_sql << %Q< TO '#{s3_uri}'>
  unload_sql << %Q< CREDENTIALS '#{credentials_string}'>
  unload_sql << %q< MANIFEST>
  unload_sql << %q< DELIMITER '\t'>
  unload_sql << %q< GZIP> if options.fetch(:compression, true)
  unload_sql << %q< ALLOWOVERWRITE> if options[:allow_overwrite]
  @logger.info(sprintf('Unloading Redshift table %s to %s', table_name, s3_uri))
  @redshift_connection.exec(unload_sql)
  @logger.info(sprintf('Unload of %s complete', table_name))
end