mysql doesn't write transaction mysql-max does write transaction for details, you can check out at mysql web site or mysql & mysql-max manual if your application doesn't need transaction, I think mysql is better for better performance
----- Original Message ----- 寄件者: "Khaled Elmeleegy" <[EMAIL PROTECTED]> 收件者: <[EMAIL PROTECTED]> 傳送日期: 2002年5月20日 PM 12:36 主旨: Concurrency control > How does MySQL handle concurrency control between two or more concurrent > quires (not transactions), on their website they say they use > multi-versioned concurrency control, but i guess this between transactions, > not queries. > > Consider the case we have two queries > > Q1: select * from table1 EXCEPT select * from table1 where id>50; > Q2:update table1 set id = id+1; > > Concurrent execution of these two queries could result in incorrect results, > if no appropriate concurrency control is used, specifically if the update > query is executed between the first half of Q1 and the second half. > > there are many other examples to this problem, so i wonder how MySQL handles > it. > > Thanks, > Khaled. > > --------------------------------------------------------------------- > Before posting, please check: > http://www.mysql.com/manual.php (the manual) > http://lists.mysql.com/ (the list archive) > > To request this thread, e-mail <[EMAIL PROTECTED]> > To unsubscribe, e-mail <[EMAIL PROTECTED]> > Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
