On Mon, 24 Mar 2025, 19:54 Derick Turner, <derick@e-learndesign.co.uk> wrote:

Update on this one.

I upped the open_table_cache to 30,000 to see what impact this would have. I would have expected the memory foot print of the MariaDB process to grow to about 30GB but it has stayed at ~27GB (as reported by btop). This was from the SQL calculation:
SELECT @@innodb_buffer_pool_size + @@key_buffer_size + @@query_cache_size + @@tmp_table_size + @@table_open_cache * @@open_files_limit + (@@sort_buffer_size + @@read_buffer_size + @@read_rnd_buffer_size + @@join_buffer_size + @@thread_stack + @@binlog_cache_size) * @@max_connections AS MaxMemoryEstimate;

That makes no sense, a file handle is about 1KB, so 30K of table_open_cache won't add more than 30MB.

Value for that returns 32082607104 (29.88GB if my maths is right).

There is a lot wrong with that equation.