Paul, Thanks for your reply. I enjoy reading your book very much It was very much helpful while development of client in C. I am embedded system engineer so please correct me if I am misssing anything in this new DBMS world.
So I understand that there is no mechanism to set priority between threads. I want to develop such mechanism using UDF. Here are my quesitions. * Mysql uses pthreads under linux platform , right? * By default their scheduling algorithm is SCHED_OTHER , what if I change it to SCHED_FIFO? * If I run any User define function(UDF) from client does it run in that thread's contex? * Can I change Scheduling algorithm and sheduling priority in UDF (user define function)? I guess if I change thread's priority and scheduling algorithm using UDF then Thread A can preempt Thread B inbetween SELECT.......is that correct?? Please let me know if I am missing anything. Regards, Naushit. > >I have question about mysqld theading. > > > >I understand that mysqld will have one thread per connection, is that > >right?? > > > > If thru, Can I assign higher priority to perticular > >thread/connection/client ? > > No. You can apply priority modifiers to individual statements, > but you state below that is not what you want. > > > > >for example , If we have two clients connected to mysqld using > >Thread A and Thread B. ( they are using same DB same TABLE). > > > >I want to give higher priority to Thread A then Thread B. > >By higher priority I mean if Thread B is doing something( > >select/update/insert or anything), > >and if there is some request on Thread A then it should preempt the Thread B > >and it should get executed first, after Thread A releses resourse Thread B > >should continue > >from where it was left. > > > >I am NOT looking for SELECT over UPDATE priority > > > >Second Question. > > > >When I use "--low-priority-updates", Will it have priority between threads? > > Yes. It applies globally. > > >for example, if Thread B is doing UPDATE and Thread A want to do SELECT, > >will Thread A > >get priority over Thread B? Will it preempt Thread B? > > No. That is, if Thread B is *already* executing an UPDATE, Thread A > can't have the server abort that UPDATE so that it can start executing > its SELECT. Once a query starts, it runs to completion. > > > > >Thanks > >Naushit. > > > >Note: I am not subcribed to Mysql list , plase cc your reply to me . > > > > --------------------------------------------------------------------- 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
