A few days ago one of our intern @mydbops reached me with a SQL query. The query scans only a row according to the execution plan. But query does not seems optimally performing. Below is the SQL query and its explain plan. ( MySQL 5.7 ) select username, role from user_roles where username= '9977223389' ORDER … Continue reading Row scanned equals to 1, Is the query is optimally tuned ?
This blog is about one of the issues encountered by our Remote DBA Team in one of the production servers. We have a setup of MySQL 5.7 Single Primary (Writer) GR with cluster size of 3 . Due to OOM, the MySQL process in the primary node got killed, this repeated over the course of … Continue reading MySQL Group Replication and its Memory consumption (troubleshooting).
Hope everyone aware about known about LVM(Logical Volume Manager) an extremely useful tool for handling the storage at various levels. LVM basically functions by layering abstractions on top of physical storage devices as mentioned below in the illustration. Below is a simple diagrammatic expression of LVM sda1 sdb1 (PV:s on partitions or whole disks) \ … Continue reading Get the most IOPS out of your physical volumes using LVM.
Recently we had been bitten by a Systemd limitation at the “Tasks” created per-unit ie., process. This includes both the kernel threads and user-space threads, with each thread counting individually. Am writing this blog as a reference for someone who might come across this limitation. We have been actively working on migration DB instances, from … Continue reading TaskMax limit affects MySQL connections
Monitoring MySQL server has never been an easy task. Monitoring also needs to go through many Complex and difficult queries to get the details. All these problems can be overcome by an excellent command line monitoring tool called “Innotop”. Innotop comes with many features and different types of modes/options, which helps to monitor different aspects … Continue reading Innotop – A Monitoring tool for MySQL
In this blog post, I am going to explain an interesting issue which I faced in one of our client project . Few weeks back , I got an requirement from our support client to construct a new MariaDB Galera Cluster ( 10.2.21 ) and an async … Continue reading Chose right SST method MariaDB Cluster 10.2
Recently we had encountered a strange issue with replication and temp directory(tmpdir) change while working for one major client. All the servers under this were running with Percona flavor of MySQL versioned 5.6.38 hosted on a Debian 8(Jessie) The MySQL architecture setup is as follows one master with 5 direct slaves under it Through this … Continue reading Impact of “tmpdir” change in MySQL replication
Introduction - Recently i worked on a production issue for one of our client under support .They have a architecture of a three node Galera cluster with one asynchronous slave . Node1 - 22.214.171.124Node2 - 126.96.36.199Node3 - 188.8.131.52Replica - 184.108.40.206 Architecture - The slave(replica) was configured with node3 as replica master. Unfortunately the node 3 was … Continue reading How to Switch Replica Master of a non-GTID Slave in Percona Cluster ?
I am a Junior DBA at Mydbops. This is my first blog professionally, I would like to brief my encounter with Log-rotate in first few weeks of my work, Hope it will help other beginners as well. This Blog will cover the following sections. Introduction to Log-rotate Issues FacedSolutions (Fix for the above issues)Best practicesHow … Continue reading Configuring efficient MySQL Logrotate
During our recent consulting with one of our client, We came across an interesting issue on RDS. The baseline is that "Low IO size on your RDS instance can affect your DB performance". Yes, It’s IO size, Not IOPS. We had our production systems running on RDS MySQL with a single master, 3 replicas. All … Continue reading Will IO Size Affect your RDS Performance?