Hi Steve,
Le 23/04/2017 à 19:32, Sales a écrit :
On our system, Mariadb 10.1.22, with aria_used_for_temp_tables = ON, we have a
set of MyISAM settings carried over from an earlier setup. Those settings are:
key_buffer_size=256M
myisam_sort_buffer_size = 64M
join_buffer_size=512K
bulk_insert_buffer_size=512M
read_rnd_buffer_size = 1M
read_rnd_buffer_size and join_buffer_size are not MyISAM specific
settings, did you try to modify/not modify only those ones ?
HTH,
Jocelyn
Looking in the information_schema, we have one entire schema of tables still
using MyISAM (third party system), and, this schema is not used in any daily
processing. The only other MyISAM tables are in the mysql schema. So, nothing
else, not one table. The way I understand aria, it should be used instead of
MyISAM even for tmp tables given our settings.
We have a long running set of programs that do things over night to manage
products, many millions of them, ends up processing at least 50 million rows of
various tables, thousands of mysql statements. This process has no MyISAM as
noted. When I disable the settings above for MyISAM, a significant runtime
increase is noted, I’ve repeated this 5 times now over a few week period. The
increase is 20%, pretty significant, and that 20% never occurs when not
changing settings. So, it would seem unlikely that I am just that unlucky.
I am curious as to why those settings for MyISAM would have an impact? There
are certainly tmp tables in the process (or internally created tmp tables) and
the rest is innodb. Any good potential reason I am missing? I have not really
looked into aria much before, read most of the mariadb doc. Maybe I missed
something key, it appears likely I did!
We have the following somewhat corresponding aria settings:
aria_pagecache_buffer_size = 256M
aria_sort_buffer_size = 256M
Steve
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