I have a DB MYSQL with many schema. Around 5k - 7k schemas.

My system sometime meet OOM Killer case.

Is that unnormal ?

we have 5 scheme different structure. The rest is the same and each schema corresponds to 1 user.

Is there any way to tunning up this db ? [I haven't found a way yet]

How to reduce OOM error rate ? [In my case, reduce inno buffer ~70% total RAM and resolve all slow query]

*NEW: Because we have many schemas with 17 tables per schema, 1 table has ~10 partitions. So in datadir each directory schema contains more than 25-30 files.

Which is the way to reduce the number of files per schema?

Should I use tablespace to store all table not use partition to reduce?