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Versions: 5
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# Copyright (c) 2011 - 2013, SoundCloud Ltd., Rany Keddo, Tobias Bielohlawek, Tobias
# Schmidt
require 'lhm/command'
require 'lhm/migration'
require 'lhm/sql_retry'
module Lhm
# Switches origin with destination table using an atomic rename.
#
# It should only be used if the MySQL server version is not affected by the
# bin log affecting bug #39675. This can be verified using
# Lhm::SqlHelper.supports_atomic_switch?.
class AtomicSwitcher
include Command
attr_reader :connection
def initialize(migration, connection = nil, options = {})
@migration = migration
@connection = connection
@origin = migration.origin
@destination = migration.destination
@retry_helper = SqlRetry.new(
@connection,
{
log_prefix: "AtomicSwitcher"
}.merge!(options.fetch(:retriable, {}))
)
end
def atomic_switch
"rename table `#{ @origin.name }` to `#{ @migration.archive_name }`, " \
"`#{ @destination.name }` to `#{ @origin.name }`"
end
def validate
unless @connection.data_source_exists?(@origin.name) &&
@connection.data_source_exists?(@destination.name)
error "`#{ @origin.name }` and `#{ @destination.name }` must exist"
end
end
private
def execute
@retry_helper.with_retries do |retriable_connection|
retriable_connection.execute atomic_switch
end
end
end
end
Version data entries
5 entries across 5 versions & 1 rubygems