I have for some years been running the queries of the DBT-3 benchmark, both to verify the effect of new query optimization features, and to detect any performance regressions that may have been introduced. However, I have had issues with getting stable results. While repeated runs of a query is very stable, I can get quite different results if I restart the server. As an example, I got a coefficient of variation (CoV) of 0.1% for 10 repeated executions of a query on the same server, while the CoV for the average runtime of 10 such experiments was over 6%!

With such large variation in results, significant performance regressions may not be noticed. I have tried a lot of stuff to get more stable runs, and in this blog post I will write about the things that I have found to have positive …

Many web hosting provider are looking for HA solution for the database backend they deliver to their customers.

Galera never became the perfect choice for these environment due to 2 factors:

1. no DBA really manage the databases
2. Galera runs database changes in Total Order Isolation

What does that really mean ? In fact, when you are a website hosting provider, you host the website (apache, nginx) on vhosts and you share a database server in which every customer has access to their own schema for their website.

Most of the time, those websites are CMS like Drupal, WordPress or Joomla (and certainly many others sharing the same …

Overview

MySQL Group Replication was released as GA with MySQL 5.7.17. It is essentially a plugin that, when enabled, allows users to set replication with this new way.

There has been some confusion about the stability and usability of this release. Until recently, MySQL Group Replication (MGR) was only available in the Labs, which traditionally denotes a preview or an use-at-your-own-risk feature. Several months ago we saw the release of Group Replication as a Docker image, which allowed users to deploy a peer-to-peer cluster (every node is a master.) However, about one month after such release, word came from Oracle discouraging this setup, and inviting users to use Group Replicator in …

MySQL is free, open source, and easily available for download. It is usually the first choice of most Web developers for learning SQL and database. Many large websites and hosting companies rely on using MySQL as their backend. Here we are outlining the simple steps to install MySQL on Windows 7. Not only does it support multiple platforms but allows quick integration with a no. of programming languages like Java, C#, and Python. In our last tutorial, we’d laid down the steps to install MySQL on Ubuntu platform. If Linux is the alternate operating system you use, then it’s worth reading this tutorial to get

The post Quick Steps to Install MySQL on Windows 7 and Things to Do Next appeared first on Learn Programming and Software Testing.

Read the step by step tutorial to install MySQL on Ubuntu 16.04 and Debian OS. Also, find steps to setup, secure, and tune MySQL for performance.

The post Easy Steps to Install MySQL on Ubuntu 16.04 and Debian OS appeared first on Learn Programming and Software Testing.

I’m also wondering that if the partitions column should be ignored for NDB tables – as you said – , why in the “Optimizing MySQL Cluster Performance” white paper, “4.3 Distribution aware application” section, the partitions column in explain output was not ignored and was actually used to confirm the partitions and the distribution key(s) in NDB tables?! That’s really confusing !

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Last week VividCortex's Preetam Jinka published a post on his personal blog examining how our engineering team had overcome a problem with MySQL replication by using a new parallelization policy introduced in MySQL 5.7: LOGICAL_CLOCK.

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The solution we developed—which achieves faster replication via group commit and a carefully calibrated delay—can offer huge replication improvements, but its implementation isn't immediately obvious or intuitive. We thought it worthwhile to provide a fuller description of how we arrived at the solution Preetam outlined.

In my previous post, I talked about a funny replication breakage that I experienced with MariaDB.  So what about different versions of MySQL... > SELECT version(); +------------+ | version() | +------------+ | 5.6.35-log | +------------+ 1 row in set (0.00 sec) > SELECT * FROM test_jfg; +----+--------+-------------+ | id | status

In the first two blogs entries on this series we set up a connection to MySQL and sent off a query. Now we need to get the data back from the database and into the application.

An Embarrassment of RichesPHP has many options for what we want to do. But for the best place to start with was checking that rows were actually returned from a query. Below the results from a query are returned to a variable named $result. We can find out how many rows were returned from the server by examining $result->num_rows.

if (!$result = $mysqli->query($sql)) {

    // Again, do not do this on a public site, but we'll show you how
    // to get the error information
    echo "Error: Our query failed to execute and here is why: \n";
    echo "Query: " . $sql . "\n";
    echo "Errno: " . $mysqli->errno . "\n";
    echo "Error: " . $mysqli->error . "\n";
    exit;
}

// succeeded, but …

A funny replication breakage kept me at the office longer than expected today (Friday 13 is not kind with me).

So question of the day: can you guess what the below UPDATE statement does (or what is wrong with it)?

> CREATE TABLE test_jfg ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, status ENUM('a','b') NOT NULL DEFAULT 'a', txt TEXT); Query OK, 0