July 30, 2014

Introducing backup locks in Percona Server

TL;DR version: The backup locks feature introduced in Percona Server 5.6.16-64.0 is a lightweight alternative to FLUSH TABLES WITH READ LOCK and can be used to take both physical and logical backups with less downtime on busy servers. To employ the feature with mysqldump, use mysqldump –lock-for-backup –single-transaction. The next release of Percona XtraBackup will […]

MySQL Error: Too many connections

We have always received quite few questions here at Percona Support on how to avoid the dreaded “Too many connections” error, as well as what is the recommended value for max_connections. So, in this article I will try to cover best possible answers to these questions so others can mitigate similar kinds of issues. My […]

Handling long-running queries in MySQL with Percona XtraBackup

I recently had a case where replication lag on a slave was caused by a backup script. First reaction was to incriminate the additional pressure on the disks, but it turned out to be more subtle: Percona XtraBackup was not able to execute FLUSH TABLES WITH READ LOCK due to a long-running query, and the […]

MySQL 5.6 Compatible Percona Toolkit 2.2 Released

A new Percona Toolkit series has been released: Percona Toolkit 2.2 for MySQL 5.6. Several months in the making and many new features, changes, and improvements make this a great new series. It replaces the 2.1 series for which we plan to do only one more bug fix release (as 2.1.10) then retire. 2.2 is […]

Percona XtraDB Cluster: Multi-node writing and Unexpected deadlocks

Percona XtraDB Cluster (PXC) and the technology it uses (Galera) is an exciting alternative to traditional MySQL replication.  For those who don’t know, it gives you: Fully Synchronous replication with a write latency increase equivalent to a ping RTT to the furthest node Automatic cluster synchronization, both incremental and full restores The ability to read […]

InnoDB’s gap locks

One of the most important features of InnoDB is the row level locking. This feature provides better concurrency under heavy write load but needs additional precautions to avoid phantom reads and to get a consistent Statement based replication. To accomplish that, row level locking databases also acquire gap locks. What is a Phantom Read A […]

How to Monitor MySQL with Percona’s Nagios Plugins

In this post, I’ll cover the new MySQL monitoring plugins we created for Nagios, and explain their features and intended purpose. I want to add a little context. What problem were we trying to solve with these plugins? Why yet another set of MySQL monitoring plugins? The typical problem with Nagios monitoring (and indeed with […]

Can we improve MySQL variable handling ?

MySQL Settings (also known as Server Variables) have interesting property. When you set variable in running server this change is not persisted in any way and server will be back to old value upon restart. MySQL also does not have option to re-read config file without restarting as some other software so approach to change […]

How to debug long-running transactions in MySQL

Among the many things that can cause a “server stall” is a long-running transaction. If a transaction remains open for a very long time without committing, and has modified data, then other transactions could block and fail with a lock wait timeout. The problem is, it can be very difficult to find the offending code […]