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From:Andrei Elkin Date:March 10 2009 9:41am
Subject:Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703
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He Zhenxing,

>> The tree states in show slave status was discussed ago with some
>> people on #support who accepted the idea.
>> Guang Bao, Zhen Xing, I think you need to speak to #support people and act in
>> consensus with them according to the two items:
>> 
>
> agree
>
>> - if the 3 states for IO in show slave status is acceptable indeed
>> - whether SHOW STATUS LIKE 'Slave_running' would report the binary,
>>   and then which of the two binaries:
>> 
>>   1) NO, YES (IO thread is started but not connected, the current  pre-bug30703)
>
> If we have to use binary states, then I'd prefer this, because when
> connecting, the slave IO thread *IS* running and this is consistent with
> START SLAVE.
>
>>   2) NO, YES (IO thread is connected)
>> 
>
> This would cause inconsistency with START SLAVE, when you see
> Slave_IO_running or variable Slave_running is 'NO' when connecting, and
> try START SLAVE IO_THREAD, it will warn that the slave is already
> running.
>

So the problem is how we define YES for SHOW STATUS LIKE 'Slave_running'.

The interpretation I am about

 'Slave_running' is YES iff  Slave_IO_Running: Yes and Slave_SQL_Running: Yes

Executing `start slave' is reentrant and besides seeing "in already
running" there is no issue.
Another reason why I would not link the Slave_running's YES definition
with `start slave' is that it's so from the engineer's perspective,
but remember SHOW:s are for the users as well.
And they seem to me won't like Slave_running's YES
if the IO is not connected (please ask that on #support for sure).


>>   or we would need to reflex the new IO 3 states in 
>>   the SHOW STATUS LIKE 'SLAVE_RUNNING'
>
> status 'Slave_running' is for both IO thread and SQL thread, so we
> cannot have the Connecting state for it.

We can have 2 * 3 states. However I am not sure if we need that.
Let's be satiesfied with the binary state based on the def above.

cheers,

Andrei
Thread
bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703Guangbao Ni4 Mar
  • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703Alfranio Correia10 Mar
    • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703Guangbao Ni10 Mar
      • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703Andrei Elkin10 Mar
        • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703He Zhenxing10 Mar
          • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703Andrei Elkin10 Mar
            • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703He Zhenxing10 Mar
              • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703Andrei Elkin10 Mar
                • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703He Zhenxing11 Mar
        • Re: bzr commit into mysql-6.0-bugteam branch (gni:3101) Bug#30703He Zhenxing10 Mar