Module: Lhm

Defined in:
lib/lhm.rb,
lib/lhm/table.rb,
lib/lhm/chunker.rb,
lib/lhm/command.rb,
lib/lhm/invoker.rb,
lib/lhm/version.rb,
lib/lhm/migrator.rb,
lib/lhm/entangler.rb,
lib/lhm/migration.rb,
lib/lhm/connection.rb,
lib/lhm/sql_helper.rb,
lib/lhm/intersection.rb,
lib/lhm/atomic_switcher.rb,
lib/lhm/locked_switcher.rb

Overview

Copyright © 2011 - 2013, SoundCloud Ltd., Rany Keddo, Tobias Bielohlawek, Tobias Schmidt

Defined Under Namespace

Modules: Command, SqlHelper Classes: AtomicSwitcher, Chunker, Connection, Entangler, Error, Intersection, Invoker, LockedSwitcher, Migration, Migrator, Table

Constant Summary collapse

VERSION = 
"2.0.0"

Class Method Summary collapse

Class Method Details

.adapter ⇒ Object 



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# File 'lib/lhm.rb', line 69

def self.adapter
  @@adapter ||=
    begin
      raise 'Please call Lhm.setup' unless defined?(ActiveRecord)
      ActiveRecord::Base.connection
    end
end

.change_table(table_name, options = {}) {|Migrator| ... } ⇒ Boolean

Alters a table with the changes described in the block

Parameters:

  • table_name (String, Symbol) —

    Name of the table

  • options (Hash) (defaults to: {}) —

    Optional options to alter the chunk / switch behavior

Options Hash (options):

  • :stride (Fixnum) —

    Size of a chunk (defaults to: 40,000)

  • :throttle (Fixnum) —

    Time to wait between chunks in milliseconds (defaults to: 100)

  • :start (Fixnum) —

    Primary Key position at which to start copying chunks

  • :limit (Fixnum) —

    Primary Key position at which to stop copying chunks

  • :atomic_switch (Boolean) —

    Use atomic switch to rename tables (defaults to: true) If using a version of mysql affected by atomic switch bug, LHM forces user to set this option (see SqlHelper#supports_atomic_switch?)

Yields:

  • (Migrator) —

    Yielded Migrator object records the changes

Returns:

  • (Boolean) —

    Returns true if the migration finishes

Raises:

  • (Error) —

    Raises Lhm::Error in case of a error and aborts the migration



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# File 'lib/lhm.rb', line 40

def self.change_table(table_name, options = {}, &block)
  origin = Table.parse(table_name, connection)
  invoker = Invoker.new(origin, connection)
  block.call(invoker.migrator)
  invoker.run(options)
  true
end

.cleanup(run = false) ⇒ Object 



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# File 'lib/lhm.rb', line 48

def self.cleanup(run = false)
  lhm_tables = connection.select_values("show tables").select do |name|
    name =~ /^lhm(a|n)_/
  end
  return true if lhm_tables.empty?
  if run
    lhm_tables.each do |table|
      connection.execute("drop table #{table}")
    end
    true
  else
    puts "Existing LHM backup tables: #{lhm_tables.join(", ")}."
    puts "Run Lhm.cleanup(true) to drop them all."
    false
  end
end

.setup(adapter) ⇒ Object 



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# File 'lib/lhm.rb', line 65

def self.setup(adapter)
  @@adapter = adapter
end