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Displaying posts with tag: Caching (reset)
Hidden caches catch your data

This article is different from my usual posts. It explains things that may be obvious to many database professionals – not all of them though.

The idea came indirectly from my friend Francesco Allertsen. He has a weekly mailing list he uses to share links to interesting articles he reads on the web. One of them was The hidden components of Web caching. Its purpose is to list all caches that play some role when we interact with a web site. An interesting idea, even if I find it incomplete. So I thought it was a good idea to talk about caches that we hit whenever we interact with a database.

Why should we care?

But first, a note on why we should care: …

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RDS Aurora MySQL and Service Interruptions

In Amazon space, any EC2 or Service instance can “disappear” at any time.  Depending on which service is affected, the service will be automatically restarted.  In EC2 you can choose whether an interrupted instance will be restarted, or left shutdown.

For an Aurora instance, an interrupted instance is always restarted. Makes sense.

The restart timing, and other consequences during the process, are noted in our post on Aurora Failovers.

Aurora Testing Limitations

As mentioned earlier, we love testing “uncontrolled” failovers.  That is, we want to be able to pull any plug on any service, and see that the environment as a whole continues to do its job.  We can’t do that with Aurora, because we can’t control the essentials:

  • power button;
  • reset switch;
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RDS Aurora MySQL Failover

Right now Aurora only allows a single master, with up to 15 read-only replicas.

Master/Replica Failover

We love testing failure scenarios, however our options for such tests with Aurora are limited (we might get back to that later).  Anyhow, we told the system, through the RDS Aurora dashboard, to do a failover. These were our observations:

Role Change Method

Both master and replica instances are actually restarted (the MySQL uptime resets to 0).

This is quite unusual these days, we can do a fully controlled role change in classic asynchronous replication without a restart (CHANGE MASTER TO …), and Galera doesn’t have read/write roles as such (all instances are technically writers) so it doesn’t need role changes at all.

Failover Timing

Failover between running instances takes about 30 seconds.  This is in line with information provided in the …

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Exploring Amazon RDS Aurora: replica writes and cache chilling

Our clients operate on a variety of platforms, and RDS (Amazon Relational Database Service) Aurora has received quite a bit of attention in recent times. On behalf of our clients, we look beyond the marketing, and see what the technical architecture actually delivers.  We will address specific topics in individual posts, this time checking out what the Aurora architecture means for write and caching behaviour (and thus performance).

What is RDS Aurora?

First of all, let’s declare the baseline.  MySQL Aurora is not a completely new RDBMS. It comprises a set of Amazon modifications on top of stock Oracle MySQL 5.6 and 5.7, implementing a different replication mechanism and some other changes/additions.  While we have some information (for instance from the “deep dive” by AWS VP Anurag Gupta), the source code of the Aurora modifications …

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This Week in Data with Colin Charles 17: AWS Re:Invent, a New Book on MySQL Cluster and Another Call Out for Percona Live 2018

Join Percona Chief Evangelist Colin Charles as he covers happenings, gives pointers and provides musings on the open source database community.

The CFP for Percona Live Santa Clara 2018 closes December 22, 2017: please consider submitting as soon as possible. We want to make an early announcement of talks, so we’ll definitely do a first pass even before the CFP date closes. Keep in mind the expanded view of what we are after: it’s more than just MySQL and MongoDB. And don’t forget that with one day less, there will be intense competition to fit all the content in.

A new book on MySQL Cluster is out: Pro MySQL NDB Cluster by Jesper Wisborg Krogh and Mikiya Okuno. At 690 pages, it is a weighty tome, and something I fully plan on reading, considering I haven’t played with …

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Application data caching using SSDs


The Moneta project: Next generation EVCache for better cost optimizationWith the global expansion of Netflix earlier this year came the global expansion of data. After the Active-Active project and now with the N+1 architecture, the latest personalization data needs to be everywhere at all times to serve any member from any region. Caching plays a critical role in the persistence story for member personalization as detailed in this earlier blog post.

There are two primary components to the Netflix architecture. The first is the control plane that runs on the AWS cloud for generic, scalable …

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ScaleArc: Real-world application testing with WordPress (benchmark test)

ScaleArc recently hired Percona to perform various tests on its database traffic management product. This post is the outcome of the benchmarks carried out by me and ScaleArc co-founder and chief architect, Uday Sawant.

The goal of this benchmark was to identify ScaleArc’s overhead using a real-world application – the world’s most popular (according to wikipedia) content management system and blog engine: WordPress.

The tests also sought to identify the benefit of caching for this type of workload. The caching parameters represent more real-life circumstances than we applied in the sysbench performance tests – the goal here was not just to saturate the cache. For this reason, we created an artificial WordPress blog with generated data. …

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Tech Messages | 2013-03-10

A special extended edition of Tech Messages for 2013-03-07 through 2013-03-10:

Some sharding support and cache locality optimization support for PHP MySQL driver

It is time for christmas presents: some sharding support and cache locality optimizations are coming with PECL/mysqlnd_ms 1.5. PECL/mysqlnd_ms is a plugin for the mysqlnd library. The plugin adds replication and load balancing support to any PHP MySQL API (mysql, mysqli, PDO_MySQL) if compiled to use the mysqlnd library.

As a MySQL user you can choose between a wide variety of clustering solutions to scale-out. Your options range from eventual consistent solutions to strong consistent ones, from built-in (MySQL Replication, MySQL Cluster) to third party or home-grown. PECL/mysqlnd_ms is a client side load balancer that aims to serve all. …

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5 Tips to Cache Websites and Boost Speed

Read the original article at 5 Tips to Cache Websites and Boost Speed

Often when we think about speeding up and scaling, we focus on the application layer itself.  We look at the webserver tier, and database tier, and optimize the most resource intensive pages.

There's much more we can do to speed things up, if we only turn over the right stones.  Whether you're using WordPress or not, many of these principals can be applied.  However we'll use WordPress as our test case.

Test Your Website speed

There are web-based speed testing tools that will help with this step.  Take a look at Webpagetest , …

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