Based on Percona Server …[Read more...]
Some applications have a heavy write workload on a few records – for instance when incrementing a global counter: this is called a write hotspot. Because you cannot update the same row simultaneously from multiple threads, this can lead to performance degradation. When using Percona XtraDB Cluster (PXC), some users try to solve this specific issue by writing on multiple nodes at the same time. Good idea or bad idea? Read on!
Simultaneous writes on a standalone InnoDB server
Say you have these 3 transactions being run …[Read more...]
I often talk with people who are very interested in the features of Percona XtraDB Cluster (PXC) such as synchronous and parallel replication, multi-node writing and high availability. However some get confused when operating a real PXC cluster because they do not fully realize the implications of these features. So here is a fun way to test your PXC knowledge: try to solve these 12 questions related to PXC! (you will find the answers at the end of the post.)
1. With Galera 3.x, support for MyISAM is experimental. When can
we expect to have full MyISAM support?
a. This will never happen as …
Percona Toolkit is one of our most mature open source applications. Derived from Maatkit and Aspersa, Percona Toolkit has evolved significantly over the years. The software now contains 32 tools, over 4,000 tests, and has been downloaded over 250,000 times. Anyone who manages a database – from DBAs to system administrators to even software developers – benefits from Percona Toolkit’s ability to perform a variety of MySQL server and system tasks that are too difficult …[Read more...]
My webinar “Multi-threaded Replication in MySQL 5.6 and 5.7″ on February 25 generated several excellent questions following the presentation (available here for playback along with the slides). I didn’t have time to answer many of the questions during the session and so in this post I answer all of them. Thanks to everyone who attended!
Q: What do you expect from MTS with logical clock? Do you
think performance would be good as with per database?
A: MTS with 5.6 is not usable …
As the need for information grows so does the size of data we need to keep in our databases. SST is unavoidable for spinning up new nodes in a PXC cluster and when datasets reach the “terra-byte” range this becomes ever more cumbersome requiring many hours for a new node to synchronize.
More often that not, it is necessary to implement custom “wsrep_sst” scripts or resort to manual synchronization processes. Luckily cloud providers provide convenient methods to leverage disk snapshots that can be used …[Read more...]
This past week was marked by a series of personal findings related to the use of Global Transaction IDs (GTIDs) on Galera-based clusters such as Percona XtraDB Cluster (PXC). The main one being the fact that transactions touching MyISAM tables (and FLUSH PRIVILEGES!) issued on a giving node of the cluster are recorded on a GTID set bearing the node’s server_uuid as “source id” and added to the binary log (if the node has …[Read more...]
Say you have a cluster with 3 nodes using Percona XtraDB Cluster (PXC) 5.6 and one asynchronous replica connected to node1. If asynchronous replication is using GTIDs, moving the replica so that it is connected to node2 is trivial, right? Actually replication can easily break for reasons that may not be obvious at first sight.
Let’s assume we have the following setup with 3 PXC nodes and one asynchronous replica:
January 27, 2015 By Severalnines
Unlike standard MySQL server and MySQL Cluster, the way to start a MySQL/MariaDB Galera Cluster is a bit different. Galera requires you to start a node in a cluster as a reference point, before the remaining nodes are able to join and form the cluster. This process is known as cluster bootstrap. Bootstrapping is an initial step to introduce a database node as primary component, before others see it as a reference point to sync up data.
How does it work?
When Galera starts with the bootstrap command on a node, that particular node will reach Primary state (check …[Read more...]