You cannot use the tx_read_only in the .cnf file. You must specifiy transaction_read_only = 1 for it to set the value of tx_read_only on system startup. Conversely we do not seem to be able to do... SET SESSION transaction_read_only = OFF; Is this intended? Rhys Campbell Database Administrator TradingScreen, Inc. 23 York House, 5th Floor London WC2B 6UJ Email: rhys.campbell@tradingscreen.com<mailto:rhys.campbell@tradingscreen.com> Follow TradingScreen on Twitter<http://twitter.com/#!/TradingScreen> , Facebook<http://www.facebook.com/pages/TradingScreen/214046251945650> and our blog Trading Smarter<tradingsmarter.tradingscreen.com> This message is intended only for the recipient(s) named above and may contain confidential information. If you are not an intended recipient, you should not review, distribute or copy this message. Please notify the sender immediately by e-mail if you have received this message in error and delete it from your system.