There are times where you need to know exactly how much memory the mysqld server (or any other program) is using, where (i.e. for what function) it was allocated, how it got there (a backtrace, please!), and at what point in time the allocation happened. For example; you may have noticed a sharp memory increase […]
One of the most painful troubleshooting tasks with MySQL is troubleshooting memory usage. The problem usually starts like this – you have configured MySQL to use reasonable global buffers, such as innodb_buffer_size, key_buffer_size etc, you have reasonable amount of connections but yet MySQL takes much more memory than you would expect, causing swapping or other […]
There are many questions how InnoDB allocates memory. I’ll try to give some explanation about the memory allocation at startup. Some important constants: NBLOCKS=count of block in innodb_buffer_pool = innodb_buffer_pool_size / 16384 OS_THREADS= if (innodb_buffer_pool_size >= 1000Mb) = 50000 else if (innodb_buffer_pool_size >= 8Mb) = 10000 else = 1000 (it’s true for *nixes, for Windows […]
Every so often people ask me the question how should they estimate memory consumption by MySQL Server in given configuration. What is the formula they could use. The reasons to worry about memory usage are quite understandable. If you configure MySQL Server so it uses too small amount of memory it will likey perform suboptimally. […]
With Performance Schema improvements in MySQL 5.6 I think we’re in the good shape with insight on what is causing performance bottlenecks as well as where CPU resources are spent. (Performance Schema does not accounts CPU usage directly but it is something which can be relatively easily derived from wait and stage information). Where we’re […]
MySQL server intensively uses dynamic memory allocation so a good choice of memory allocator is quite important for the proper utilization of CPU/RAM resources. Efficient memory allocator should help to improve scalability, increase throughput and keep memory footprint under the control. In this post I’m going to check impact of several memory allocators on the […]
The latest Percona Server release has one new feature: now MEMORY tables can have BLOB and TEXT columns, and VARCHAR columns will not waste space due to implicit extension to CHAR.
I vaguely recall a couple of blog posts recently asking something like “what’s the formula to compute mysqld’s worst-case maximum memory usage?” Various formulas are in wide use, but none of them is fully correct. Here’s why: you can’t write an equation for it.
One common question I guess is how much should I see performance improved in case I increase memory say from 16GB to 32GB. The benefit indeed can be very application dependent – if you have working set of say 30GB with uniform data access raising memory from 16GB to 32GB can improve performance order of […]
Quite frequently I would log in to customers system and find MySQL using too much memory. I would look at memory consumed by Innodb (it is often higher than innodb_buffer_pool_size) substract memory used by other global buffers such as query_cache_size and key_buffer and will in many cases see some mysterous memory which I can’t really […]