On Wed, Mar 4, 2009 at 8:42 PM, Morten Primdahl wrote:
> around while trying to figure out why the first query was slow and the
> subsequent snappy.
Given that you posted that a MySQL restart does not change anything,
but a system restart does, I put my money on the filesystem cache
having buffer
On Mar 4, 2009, at 8:38 PM, Jocelyn Fournier wrote:
Just curious : if there's no index on the column why don't you try
to add one ? That's probably why it takes a lot of time on the
production machine.
Hehe.. I can understand why you ask, I over simplified the question
which was wrong of
Just curious : if there's no index on the column why don't you try to
add one ? That's probably why it takes a lot of time on the production
machine.
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
I did some tests a couple of weeks ago, using using SQL_NO_CACHE and
clearing out the OS buffer after each query was enough to give me
consistent results that were based on system load rather than cache
efficiency. These two are by far the major factors in my experience,
although no doubt other
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 500.00
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 w
If SQL_NO_CACHE is specify, the cache will never be used :
The Query Cache behaviour is quite simple, it uses the exact given query
syntax as a hash to search into the query cache;
it means writing 'select' or 'SELECT' is different. It also means adding
SQL_NO_CACHE will search in the cache for
On Wed, Mar 4, 2009 at 11:23 AM, Thomas Spahni wrote:
> SQL_NO_CACHE means that the query result is not cached. It does not mean
> that the cache is not used to answer the query.
Oh, right, he's looking for this:
SET SESSION query_cache_type=off;
- Perrin
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MySQL General Mailing List
For lis
On Wed, 4 Mar 2009, Morten wrote:
Hi, I was hoping that using SQL_NO_CACHE would help me bypass the query
cache, but judging from the below it doesn't. What can I do to avoid the
query cache?
Thanks.
Morten
mysql> select count(*) from users where email = 'hello';
+--+
| count(*) |
On Wed, Mar 4, 2009 at 10:27 AM, Morten wrote:
> Hi, I was hoping that using SQL_NO_CACHE would help me bypass the query
> cache, but judging from the below it doesn't.
You probably just brought the data into the cache and are not hitting
the query cache.
- Perrin
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MySQL General Mailing List
Keep in mind the file system caches too, so it might be working, but the
file access is still getting put in memory. You should disable that too
if you really want consistent results.
In Linux you can dump the file system cache between each query, I have
no clue how to do it in windows or other sy
In an update to the last, I think I have the issue in hand:
I am using TOAD 1.0 and it seems to be doing some sort of caching itself
or going directly to the query cache. I issued the identical query and
it would return the result immediately.
Checking Mytop (did I mention that JZ rules?) the q
One possibility is that the OS has the portion of disk that the row is
stored in cached in memory via its normal disk caching after the first
execution. Another possibility is that the key for the table is in
mysql's key_buffer after the first execution. If you are using innodb
then it might be c
On Tue, 13 Jan 2004, Priyanka Gupta wrote:
> Hi,
>
> I am trying to do some performance analysis by trying different indexing
> schemes and testing how long it takes. To get consistent results, I would
> like to use something like SQL_NO_CACHE. However, the mysqld version that I
> have installed d
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