Re: bzr commit into mysql-5.1-bugteam branch (davi:2728) Bug#40536

[Konstantin Osipov]

* Davi Arnaut <Davi.Arnaut@stripped> [09/01/14 03:11]:
>> On Jan 06, Davi Arnaut wrote:
>>> # At a local mysql-5.1-bugteam repository of davi
>>>
>>>   2728 Davi Arnaut	2009-01-06
>>>        Bug#40536: SELECT is blocked by INSERT DELAYED waiting on
>>>                   upgrading lock, even with low_pri
>>>
>>>        The problem is that there is no mechanism to control whether a
>>>        delayed insert takes a high or low priority lock on a table.
>>>
>>>        The solution is to add a new global variable which specifies
>>>        whether a delayed insert thread should take high or low priority
>>>        locks. The name of the variable is low_priority_delayed_updates.
>>
>> I think this new feature is uncalled for.
>> Why don't you use low_priority_updates ?
>>
>
> Because the session value of the variable wouldn't be meaningful, which 
> requires the global value to be used and such change could create some 
> confusion for cases where the session value of the variable differs from 
> the global one.
>
> Another thing is that one won't know the point in time that a “handler” 
> thread will acquire the lock, so the variable will probably stay set for 
> long periods.. which conflicts with the finer grained behavior of 
> low_priority_updates.
>
> My thinking is that the intrinsic details of this are better served by a 
> new variable. Besides, it was a suggestion by one of our support engineers. 
> But either way will do it.. final word is yours.

Why is this suddenly a 5.1 mru? This behaved like that since
introduction of the feature.

I agree with Serg you should take the value from the global value
of low_priority_updates.

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