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From:Morten Primdahl Date:March 4 2009 5:26pm
Subject:Re: SQL_NO_CACHE
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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