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20131223032112_switch_to_json_serialization.rb 2.5KB

    class SwitchToJsonSerialization < ActiveRecord::Migration FIELDS = { :agents => [:options, :memory], :events => [:payload] } def up if data_exists? puts "This migration will update tables to use UTF-8 encoding and will update Agent and Event storage from YAML to JSON." puts "It should work, but please make a backup before proceeding!" print "Continue? (y/n) " STDOUT.flush exit unless STDIN.gets =~ /^y/i set_to_utf8 translate YAML, JSON end end def down if data_exists? translate JSON, YAML end end def set_to_utf8 if mysql? %w[agent_logs agents delayed_jobs events links users].each do |table_name| quoted_table_name = ActiveRecord::Base.connection.quote_table_name(table_name) execute "ALTER TABLE #{quoted_table_name} CONVERT TO CHARACTER SET utf8" end end end def mysql? ActiveRecord::Base.connection.adapter_name =~ /mysql/i end def data_exists? events = ActiveRecord::Base.connection.select_rows("SELECT count(*) FROM #{ActiveRecord::Base.connection.quote_table_name("events")}").first.first.to_i agents = ActiveRecord::Base.connection.select_rows("SELECT count(*) FROM #{ActiveRecord::Base.connection.quote_table_name("agents")}").first.first.to_i agents + events > 0 end def translate(from, to) FIELDS.each do |table, fields| quoted_table_name = ActiveRecord::Base.connection.quote_table_name(table) fields = fields.map { |f| ActiveRecord::Base.connection.quote_column_name(f) } page_start = 0 page_size = 1000 page_end = page_start + page_size begin rows = ActiveRecord::Base.connection.select_rows("SELECT id, #{fields.join(", ")} FROM #{quoted_table_name} WHERE id >= #{page_start} AND id < #{page_end}") puts "Grabbing rows of #{table} from #{page_start} to #{page_end}" rows.each do |row| id, *field_data = row yaml_fields = field_data.map { |f| from.load(f) }.map { |f| to.dump(f) } yaml_fields.map! {|f| f.encode('utf-8', 'binary', invalid: :replace, undef: :replace, replace: '??') } update_sql = "UPDATE #{quoted_table_name} SET #{fields.map {|f| "#{f}=?"}.join(", ")} WHERE id = ?" sanitized_update_sql = ActiveRecord::Base.send :sanitize_sql_array, [update_sql, *yaml_fields, id] ActiveRecord::Base.connection.execute sanitized_update_sql end page_start += page_size page_end += page_size end until rows.count == 0 end end end