I'm seeking help to understand what happens when the following command line is executed:
root@prodn$ service mysqld stop
Yes, it shuts down the MySQL server so access to it is no longer available until the service is started again. However, more specifically, is there anything else that happens when the service is stopped? Forgive my novice-ness here but when mysqld is restarts, does it mean that logs were flushed, some memory freed, caches emptied, etc.?
The reason I ask is the following:
Our data warehouse DB is a MySQL DB and in the past 4 months, it has taken on average 8.5 hours.
Last Wednesday, I've stopped the mysql service, and then restarted it after 30 minutes. Since, I begin to notice a massive improvement on overall performance -- SELECT/INSERT/UPDATE/DELETE processes were more efficient. DW finished almost 4 hours earlier with the same number of rows of data
However, with each passing day, 15-20 minutes is somehow added to the finish time. So, I suspect I may have to restart the service weekly.
Is there an explanation for this behavior? I don't know what other questions are relevant but it'd be brilliant to know what happens when
mysqld service restarts.
Can anyone shed some light on this please?