Beware of your Backup before upgrading MySQL 8.0.30

MySQL 8.0.30 was released on 26-07-2022. It has a good list of features. Generated Invisible Primary Key Dynamic Redo log Sizing Instruments to monitor group replication memory Support for Ubuntu 22.04 A most notable feature for Database Administrators and database reliability engineers is Dynamic redo logging. The more widely adopted open-source backup tool is Xtrabackup. … Continue reading Beware of your Backup before upgrading MySQL 8.0.30

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Troubleshooting XA transactions in MySQL

This is one of the exciting troubleshooting related to XA transactions let’s dive in. Let me provide a few backgrounds. For one of our clients, when we try to drop a table, it is waiting for metadata lock. On debugging it is one of the XA transactions is holding the shared write lock and causing … Continue reading Troubleshooting XA transactions in MySQL

MySQL “No space left on device from storage engine”

We have planned for archiving the data to improve the DB performance and to reclaim the space. We were evaluating Compression in InnoDB and TokuDB. To find out the best compression method. We started benchmarking the compression ratio between InnoDB and TokuDB. Everything goes well for some time, but after a few hours got an … Continue reading MySQL “No space left on device from storage engine”

Handling case sensitive column in pt-archiver

To copy the data of the particular column of the table to another table/server, We have an option to export the data as CSV and import the data back to a different table. But when the table size is large and we need to copy the data only for the required data to the target … Continue reading Handling case sensitive column in pt-archiver

Troubleshooting an unique key addition during pt-online-schema-change

We all tried various alternative methods for modifying the table structure, but pt-online-schema-change (pt-osc) is the most convenient and preferred method for performing the alter online. It has more granular control too. But it may lead to data loss if proper precautionary steps are not taken care of. In this blog, we are going to … Continue reading Troubleshooting an unique key addition during pt-online-schema-change

MySQL ERROR Log Table Explained

Over the decades we have been reading the MySQL error log from the server system file, if there are any issues in MySQL or any unknown restart happened , generally we look at the mysql error log. By default MySQL error log can be found in the default path /var/log/mysqld.log , or it can be … Continue reading MySQL ERROR Log Table Explained

XtraDB Cluster troubleshooting a rejected node.

PXC(Percona XtraDB Cluster), aka Galera cluster, is one of my favorite clustering technology for MySQL that comes with real Multi-master capabilities, Write-set based nearly real-time replication and many more features. I could proudly say that Mydbops is one of the very few companies who have been supporting mission-critical clusters and preaching PXC ie., Galera cluster … Continue reading XtraDB Cluster troubleshooting a rejected node.

Row scanned equals to 1, Is the query is optimally tuned ?

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 ?

MySQL Group Replication and its Memory consumption (troubleshooting).

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).

Get the most IOPS out of your physical volumes using LVM.

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.