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From:Andrés Tello Date:April 5 2013 9:56pm
Subject:Re: Update and lock question.
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Thanks Urvashi.

Based on your answer, instead of the data I looked into the index, and it
appears that it was an index issue...

I think I have nailed the wait lock contdition due a updating indexes
unnecesarely...


On Thu, Apr 4, 2013 at 10:52 AM, Urvashi Pathak <Urvashi_Pathak@stripped
> wrote:

>
>
> Hi Andrés,
>
> Select for update makes sure that no other process can change the data
> between you selected it for update and then actually changed it and commit
> it.
> If you do not use "select for update"  then it is possible that some other
> process can change the data  in the mean time between you selected and
>  actually changes it. In this case you not see the result you actually
> intend to have.
>
> Innodb will only lock whole table only if there is no where clause in the
> update statement, which I sure you do not have. Innodb follows row level
> locking.
>
>
> -Urvi
>
> -----Original Message-----
> From: Andrés Tello [mailto:mr.criptos@stripped]
> Sent: Thursday, April 04, 2013 9:08 AM
> To: mysql
> Subject: Update and lock question.
>
> I'm doing some tests, but have a questions about locking.
>
> In a innodb table, if you issue an select for update lock for a row,
> supposedly, it only locks that row, but if you don't issue a select for
> update, and trow the update... does it locks the hole table?
>
> The update goes over an indexed field, or the effect of locking the hole
> table is due I'm updating an indexed field?
>
> This is because I'm running into dead locks, but I know there is no select
> for update to the row being updated.
>
>
> Thanks.
>

Thread
Update and lock question.Andrés Tello4 Apr
  • RE: Update and lock question.Urvashi Pathak4 Apr
    • Re: Update and lock question.Andrés Tello5 Apr
      • RE: Update and lock question.Rick James9 Apr