Djas2016-04-27 19:32:12
Djas, 2016-04-27 19:32:12

After moving to MySQL 5.7.12 from MariaDB 5.5.46, queries stopped caching. What can be wrong?

Hello. After moving to a new server, we decided to change the database server at the same time. But we noticed that the site began to work more slowly, although the new server should be more productive. We climbed to understand - we found that requests that were previously cached were no longer cached. With the query cache enabled, the SHOW GLOBAL STATUS LIKE 'Qcache%' command produces adequate results. Tell me, please, who came across, what could be the matter?

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landergate, 2016-04-27

Qcache "warms up" during some time of service operation.
Maybe not enough time passes between restarts?
Maybe users haven't had time to trigger requests for the cache yet?
After how much uptime did the cache build up earlier, and how long have you been watching it since the start of the service?
By default, query_cache_size = 0.
You need to specify the available memory for it to start working.
It's off by default due to limitations in some environments: https://mariadb.com/kb/en/mariadb/query -cache/#lim...
Maybe the new server has significantly slower disks?
You can enable slow query log and see what exactly the application is choking on or measure the IOPS of new disks. =) Or look at iowait storage for the database using the "ioping" tool.

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