Search Results for: mysql trigger lock

The MySQL Query Cache: How it works, plus workload impacts (good and bad)

Query caching is one of the prominent features in MySQL and a vital part of query optimization. It is important to know how it works as it has the potential to cause significant performance improvements – or a slowdown – of your workload. The MySQL query cache is a global one shared among the sessions. It caches […]

Diagnosing SST errors with Percona XtraDB Cluster for MySQL

State Snapshot Transfer (SST) is used in Percona XtraDB Cluster (PXC) when a new node joins the cluster or to resync a failed node if Incremental State Transfer (IST) is no longer available. SST is triggered automatically but there is no magic: If it is not configured properly, it will not work and new nodes […]

Schema changes in MySQL for OpenStack Trove users

People using OpenStack Trove instances can hit a common issue in the MySQL world: how to perform schema change operations while minimizing the impact on the database server? Let’s explore the options that can allow online schema changes. Summary With MySQL 5.5, pt-online-schema-change from Percona Toolkit is your best option for large tables while regular […]

Avoiding MySQL ALTER table downtime

MySQL table alterations can interrupt production traffic causing bad customer experience or in worst cases, loss of revenue. Not all DBAs, developers, syadmins know MySQL well enough to avoid this pitfall. DBAs usually encounter these kinds of production interruptions when working with upgrade scripts that touch both application and database or if an inexperienced admin/dev […]

Typical misconceptions on Galera Replication for MySQL

Even if a Galera node looks like a regular MySQL server, the underlying replication mechanism is very different. This implies some changes in the way you have to configure the Galera nodes. Here are some of the most common misconceptions about Galera when using Percona XtraDB Cluster. Q: Why should I enable binary logging as […]

Q&A: Percona XtraDB Cluster as a MySQL HA solution for OpenStack

Thanks to all who attended my Nov. 12 webinar titled, “Percona XtraDB Cluster as a MySQL HA Solution for OpenStack.” I had several questions which I covered at the end and a few that I didn’t. You can view the entire webinar and download the slides here. Q: Is the read,write speed reduced in Galera […]

MySQL Replication: ‘Got fatal error 1236′ causes and cures

MySQL replication is a core process for maintaining multiple copies of data – and replication is a very important aspect in database administration. In order to synchronize data between master and slaves you need to make sure that data transfers smoothly, and to do so you need to act promptly regarding replication errors to continue […]

MySQL & OpenStack: How to overcome issues as your dataset grows

MySQL is the database of choice for most OpenStack components (Ceilometer is a notable exception). If you start with a small deployment, it will probably run like a charm. But as soon as the dataset grows, you will suddenly face several challenges. We will write a series of blog posts explaining the issues you may […]

Monitoring MySQL flow control in Percona XtraDB Cluster 5.6

Monitoring flow control in a Galera cluster is very important. If you do not, you will not understand why writes may sometimes be stalled. Percona XtraDB Cluster 5.6 provides 2 status variables for such monitoring: wsrep_flow_control_paused and wsrep_flow_control_paused_ns. Which one should you use? What is flow control? Flow control does not exist with regular MySQL replication, […]