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From:jocelyn fournier Date:March 4 2009 5:56pm
Subject:Re: SQL_NO_CACHE
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MySQL Key buffer and OS cache could also have an impact.
Have you tried disabling the Key Buffer first ?

   Jocelyn

Le 04/03/2009 18:26, Morten Primdahl a écrit :
>
> Thanks for all the suggestions. The caching must be done somewhere 
> else. There is no index on the column and there are about 500.000 rows 
> in the table. A MySQL restart doesn't "flush" the cache in play, but a 
> full restart of my laptop does (OS X).
>
> I may be chasing the wrong problem, but we have seen a query take a 
> lot of time on a production machine and have not been able to pin 
> point why, as the EXPLAIN looks good and the query is responsive 
> enough when I run it manually. I was just trying to reproduce that.
>
> The below is after a full restart:
>
> mysql> SET SESSION query_cache_type=off;
> Query OK, 0 rows affected (0.00 sec)
>
> mysql> select SQL_NO_CACHE count(*) from users where email = 'hello' 
> AND 456 = 456;
> +----------+
> | count(*) |
> +----------+
> |        0 |
> +----------+
> 1 row in set (28.80 sec)
>
> mysql> RESET QUERY CACHE;
> Query OK, 0 rows affected (0.00 sec)
>
> mysql> select SQL_NO_CACHE count(*) from users where email = 'hello' 
> AND 789 = 789;
> +----------+
> | count(*) |
> +----------+
> |        0 |
> +----------+
> 1 row in set (0.44 sec)
>
>
>
>
>
>
>

Thread
SQL_NO_CACHEMorten4 Mar
  • Re: SQL_NO_CACHEMicah Stevens4 Mar
  • Re: SQL_NO_CACHEPerrin Harkins4 Mar
  • Re: SQL_NO_CACHEThomas Spahni4 Mar
    • Re: SQL_NO_CACHEPerrin Harkins4 Mar
      • Re: SQL_NO_CACHEjocelyn fournier4 Mar
        • Re: SQL_NO_CACHEMorten Primdahl4 Mar
          • Re: SQL_NO_CACHEjocelyn fournier4 Mar
            • Re: SQL_NO_CACHEMicah4 Mar
          • Re: SQL_NO_CACHEJocelyn Fournier4 Mar
            • Re: SQL_NO_CACHEMorten Primdahl4 Mar
              • Re: SQL_NO_CACHEJohan De Meersman4 Mar