On 24/03/2025 18:00, Gordan Bobic wrote:


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.
Ah - that is excellent news.  I worried that a large value would absolutely kill the memory.  So, plenty of space to increase this a long way.

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


There is a lot wrong with that equation.
Anything quick and dirty you would recommend instead (And yes I still need to set up the proper monitoring tool :)
-- 
Derick Turner - He/Him