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From:Michael Widenius Date:January 28 2000 3:39am
Subject:Delay_key_writes and some other stuff.
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Hi!

>>>>> "Peter" == Peter Zaitsev <pz@stripped> writes:

Peter> Well few weeks ago I got mysqld running stable and so I desided to turn on
Peter> delay_key_writes for some critical tables. It worked really good until I got
Peter> MYSQLD crash ones - there I have descovered how much I have to pay for
Peter> that - really long time of repearing tables.
Peter> Now Until I find the qure for MYSQLD crashes  I would wish to turn this
Peter> delay_key_write off for all of the tables to minimize down time if mysqld
Peter> craches. I can't do this  by alter table because it takes about 24hours to
Peter> do (As I was turning this on).

Peter> Well Monty told me to use  skip-new or safe-mode.    I used the first one
Peter> and it does not disable delayed_key_writes for all tables !!!
Peter> I'm not shure if I can use safe-mode as I really in trouble with perfomance.

Peter> Could you please document what exactly do skip-new and safe-mode disable and
Peter> how they would affect perfomance  because the only thing you can find in the
Peter> manual is that  they both disable some stuff and so MYSQLD could run more
Peter> stable in case of problems.

Peter> Additionaly I think some other people could have a problem as I do - so may
Peter> be there is a possibility to make an option negative to
Peter> delay_key_writes_for_all_tables to solve the problems sometimes.

Why do you think that --skip-new doesn't disable delayed_key_writes;
It should do it!

What --skip-new does:

- Make the table type of new tables ISAM by default.
  (On can use --skip-new --default-table-type=myisam if you don't like
  this)
- Don't do any delayed_key_writes.
- Don't do concurrent inserts.

--safe-mode does:
- Don't do any delayed_key_writes.
- Don't do concurrent inserts.
- Disable a lot of optimizations that 'may' go wrong in some context.

Regards,
Monty
Thread
Delay_key_writes and some other stuff.Peter Zaitsev27 Jan
  • Delay_key_writes and some other stuff.Michael Widenius28 Jan