> On Apr 23, 2017, at 3:00 PM, Federico Razzoli <federico_...@yahoo.it> wrote:
> 
> Steve,
> 
> aria_used_for_temp_tables only affects internally created temporary tables, 
> not the temp tables created explicitly by applications.
> So I suggest:
> * check if your applications create MyISAM (temporary) tables
> * use the slow log (long_query_time=0, min_examine_rows=0) and 
> pt-query-digest to check which queries are slower when you comment those 
> settings
> 
> Federico
> 

Yes, the default engine for tables is innodb as evidenced by 
default_storage_engine, so, those are not using MyISAM. The 
default_tmp_storage_engine defaults to nothing, so, according to the doc, this 
means it uses default_storage_engine, which means innodb again. I was merely 
pointing out that all temp tables are not using MyISAM, or at least should not 
be. 

Have used the slow query log and Percona toolkit with various length settings 
and did not give much benefit sadly. It showed some queries running longer, 
but, that did not help too much as far as why since the queries were using 
optimal query paths. We have many long running queries and that’s fine as these 
are calculations and mass imports from suppliers, pricing, etc. We’ve just been 
unable to make sense of the why of it. A second potential hint is mariadb 10.1 
has performed slower than mariadb 5.5 on the same machine, and thus far, we’ve 
been unable to isolate why. It’s not slower by a lot, maybe 5%. 

The word MyISAM does not exist anywhere in our code. Simple grep -ri shows 
this. It’s puzzling to me. Kind of makes me want to explicitly set 
default_tmp_storage_engine just to see if any effect.

I am just checking if anything might still use MyISAM despite these settings. 
It’s not a big deal as the settings don’t use a tremendous amount of memory by 
any means, but, was hoping to just size MyISAM all the way down. And then 
became curious as to why this might be. 

Thanks!


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