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Improved wsrep-stages and related instrumentation in Percona XtraDB Cluster

 | April 24, 2017 |  Posted In: MySQL, Percona XtraDB Cluster, XtraDB Cluster

wsrep-stages

In this blog post, we’ll look at how we’ve improved wsrep-stages and related instrumentation in Percona XtraDB Cluster. Introduction When you execute a workload and need to find out what the given thread is working on, “SHOW PROCESSLIST” comes to the top of your mind. It is an effective way to track the thread status. We […]

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Percona XtraDB Cluster Transaction Replay Anomaly

 | April 23, 2017 |  Posted In: MySQL, Percona XtraDB Cluster, XtraDB Cluster

wsrep-stages

In this blog post, we’ll look at a transaction replay anomaly in Percona XtraDB Cluster. Introduction Percona XtraDB Cluster/Galera replays a transaction if the data is non-conflicting but, the transaction happens to have conflicting locks. Anomaly Let’s understand this with an example: Let’s assume a two-node cluster (node-1 and node-2) Base table “t” is created […]

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BEWARE: Increasing fc_limit can affect SELECT latency

 | April 22, 2017 |  Posted In: MySQL, Percona XtraDB Cluster, XtraDB Cluster

SELECT Latency

In this blog post, we’ll look at how increasing the fc_limit can affect SELECT latency. Introduction Recent Percona XtraDB Cluster optimizations have exposed fc_limit contention. It was always there, but was never exposed as the Commit Monitor contention was more significant. As it happens with any optimization, once we solve the bigger contention issues, smaller […]

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More Trackable Flow Control for Percona XtraDB Cluster

 | April 20, 2017 |  Posted In: MySQL, Percona XtraDB Cluster

wsrep-stages

In this blog post, we’ll discuss trackable flow control in Percona XtraDB Cluster. Introduction Percona XtraDB Cluster has a self-regulating mechanism called Flow Control. This mechanism helps to avoid a situation wherein the weakest/slowest member of the cluster falls significantly behind other members of the cluster. When a member of a cluster is slow at applying write-sets […]

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How We Made Percona XtraDB Cluster Scale

 | April 19, 2017 |  Posted In: MySQL, Percona XtraDB Cluster, XtraDB Cluster

wsrep-stages

In this blog post, we’ll look at the actions and efforts Percona experts took to scale Percona XtraDB Cluster. Introduction When we first started analyzing Percona XtraDB Cluster performance, it was pretty bad. We would see contention even with 16 threads. Performance was even worse with sync binlog=1, although the same pattern was observed even with […]

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Galera Cache (gcache) is finally recoverable on restart

 | November 30, 2016 |  Posted In: MySQL, Percona XtraDB Cluster, XtraDB Cluster

Gcache

This post describes how to recover Galera Cache (or gcache) on restart. Recently Codership introduced (with Galera 3.19) a very important and long awaited feature. Now users can recover Galera cache on restart. Need If you gracefully shutdown cluster nodes one after another, with some lag time between nodes, then the last node to shutdown holds […]

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All You Need to Know About GCache (Galera-Cache)

 | November 16, 2016 |  Posted In: High-availability, MySQL, Percona XtraDB Cluster, XtraDB Cluster

GCache

This blog discusses some important aspects of GCache. Why do we need GCache? Percona XtraDB Cluster is a multi-master topology, where a transaction executed on one node is replicated on another node(s) of the cluster. This transaction is then copied over from the group channel to Galera-Cache followed by apply action. The cache can be discarded immediately […]

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How Percona XtraDB Cluster certification works

 | April 17, 2016 |  Posted In: Percona XtraDB Cluster

Percona XtraDB Cluster 5.7

In this blog, we’ll  discuss how Percona XtraDB Cluster certification works. Percona XtraDB Cluster replicates actions executed on one node to all other nodes in the cluster and make it fast enough to appear as it if is synchronous (aka virtually synchronous). Let’s understand all the things involved in the process (without losing data integrity). There are […]

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