class BigShift::RedshiftUnloader

Public Class Methods

new(redshift_connection, aws_credentials, options={}) click to toggle source
# 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

Public Instance Methods

unload_to(schema_name, table_name, s3_uri, options={}) click to toggle source
# File lib/bigshift/redshift_unloader.rb, line 9
def unload_to(schema_name, table_name, s3_uri, options={})
  table_schema = RedshiftTableSchema.new(schema_name, 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 "#{schema_name}"."#{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[:compression] || options[:compression].nil?
  unload_sql << %q< ALLOWOVERWRITE> if options[:allow_overwrite]
  unload_sql << %q< MAXFILESIZE 3.9 GB>
  @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