Re: Unexpected RAM usage on MySQL
Posted by: Matteo Tassinari
Date: March 14, 2019 02:08AM

Peter Brawley Wrote:
> InnoDB buffer pool is using just 12% of your
> current 16GB RAM yet is 40% free. The above
> numbers suggest to me that most of the data is in
> MariaDB aria tables ... if that's so, you're going
> to need to ask the MariaDB folks for help with
> that side of optimisation.

Now, that would be really strange, considering that we do not use the Aria storage engine at all, at least not in "our" part of the database, I do not know about its internal usage.

What I can say about the server being overloaded, is that it currently hosts a multitenant application in which each database is copied, under a different name, for each different customer.

One database is currently made of about 2800 tables, all using the InnoDB storage engine, except a couple of tables using the Memory storage engine.

The server on which I am concentrating right now is the one which hosts the most customers, there are in fact 18 customers on that one.

That makes 19 copies of a database with about 2800 tables each, for a grand total of about 53200 tables.

I have tried twice again to execute the query you gave me, during the night after a fresh database restart, but still both times the database crashed.

I'll try once again tonight, instead of having the server do the computation, I'll just do something like this:

select table_schema, table_name, engine, data_length, index_length
from information_schema.tables

and then collect the data in a spreadsheet and sum the data myself.

BTW, thanks for your help so far!

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