Posts

Showing posts from August, 2019

Debugging MySQL Memory Alerts: When innodb_buffer_pool_size Isn't the Whole Story

Image
Posted on MySQL Ninjas | August 2026 Every DBA has been there. An alert fires. You SSH into the box, run free -h , and see MySQL consuming far more RAM than you configured. You double-check innodb_buffer_pool_size . It's set correctly. So where is the memory going? This is the story of debugging exactly that — on a Google Cloud c4d-standard-4 instance with 14.7 GB RAM, MySQL configured with a 7168 MB buffer pool, and mysqld RSS sitting at 10.4 GB . That's a 3.2 GB gap nobody could explain. The Setup We run a large MySQL fleet on GCP — over 200 DR replica nodes across three datacenters. As part of a buffer pool tuning project (fitting the right pool size to the right machine class), we set innodb_buffer_pool_size = 7168 MB on our c4d-standard-4 nodes (16 GB RAM, 14.7 GB usable). Shortly after, memory alerts started firing. When I looked at what was actually happening: $ ps aux | grep mysqld | awk '{print $6/1024 " MB"}' 10490 MB ...
Post a Comment
Read more

Shell/Bash Commands Execution from MySQL Client or Stored Procedure/function

Image
Today I am going to explain ways to execute shell or bash commands from mysql clients or stored procedure and function. There are basically 2 method to do so: Method 1: Use MySQL Client inbuilt feature  To run single command: \! command or system command. eg \! uptime or system command  To get terminal \! bash or \! sh Method 2: Deploy external plugin ( lib_mysqludf_sys ) Step 1: Download lib_mysqludf_sys from github: git clone https://github.com/mysqludf/lib_mysqludf_sys.git Step 2: Install libmysqlclient15-dev, for Ubuntu you can use: apt-get install libmysqlclient15-dev Step 3: Note down o/p of: mysql -uroot -pxxxx -e "select @@plugin_dir;" Step 4: Change directory to git clone dir. cd lib_mysqludf_sys/ Step 5: Compile and put plugin in plugin dir gcc -Wall -I/usr/include/mysql -I. -shared lib_mysqludf_sys.c -o {value from step 3}lib_mysqludf_sys.so -fPIC Step 6: Create necessary functions for lib_mysqludf_sys: mysql -uroo...
1 comment
Read more