Thanks to everyone who joined us for our recent live webinar on ‘Schema Changes for MySQL Replication & Galera Cluster’ led by Krzysztof Książek, Senior Support Engineer at Severalnines. The replay and slides to the webinar are now available to watch and read online via the links below.
Watch the replay
Become a MySQL DBA - Webinars - Schema Changes for MySQL Replication & Galera Cluster (Replay) from Severalnines AB
Read the slides
[Read more]I recently gave Terraform a test drive, using HP Cloud (Openstack-based) as the cloud provider, and have to say I was pleasantly surprised that it was one of these “just works” types of tools.
Why??
I am a member of HP Cloud’s Advanced Technology Group and an important part of our mission is to look for new technologies and exciting new trends. One project I was asked to look at is Terraform. What is Terraform? A project by HashiCorp that is for “building, changing, and versioning infrastructure safely and efficiently”. From my experience, it’s a logical way of setting up virtual resources that supports multiple sources.
Installing Terraform
Installing and setting up Terraform was extremely simple and straightforward, and I was able to get up and running rather quickly, …
[Read more]
Percona Server 5.6.21+ and MySQL 5.7.8+ offer the super_read_only option that was first
implemented in WebscaleSQL. Unlike read_only, this
option prevents all users from running writes (even those with
the SUPER privilege). Sure enough, this is a great feature, but
what’s the relation with GTID? Read on!
TL;DR
Enabling super_read_only on all slaves when using
GTID replication makes your topology far less sensitive to errant
transactions. Failover is then easier and safer because creating
errant transactions is much harder.
GTID replication is awesome…
For years, all MySQL DBAs in the world have been fighting with positioning when working with replication. Each time you move a slave from one master to another, you must be very careful to start …
[Read more]The MySQL Fabric team is pleased to announce that a new (GA) release is now available. This release includes several improvements in terms of stability and usability (bug fixes and feature enhancements). In a nutshell:
…
The MySQL Fabric team is pleased to announce that a new (GA)
release is now available. This release includes several
improvements in terms of stability and usability (bug fixes and
feature enhancements). In a nutshell:
In Python it is easily possible to findout the name of a Unicode
character and findout some properties about that character. The
module which does that is called unicodedata.
An example:
>>> import unicodedata
>>> unicodedata.name('☺')
'WHITE SMILING FACE'This module uses the data as released in the UnicodeData.txt file from the unicode.org website.
So if UnicodeData.txt is a 'database', then we should be able to import it into MySQL and use it!
I wrote a small Python script to automate this. The basic steps are:
LOAD DATA LOCAL INFILE to load the data
This isn't difficult especially because the file doesn't have the actual characters in it. It is …
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Recently, we had an issue in our application which is a single
page application(SPA). We have all the functionality in a single
page and most of the data and view changes happen through ajax
requests and iframe page displays.We are using CodeIgniter
framework for this application. So sometimes what happened was
the user was logged out while accessing the application and this
occurred once a while for 1 or 2 users, not a reproducible case
one would say.Before starting on the case, I would like to
specify the steps which CodeIgniter takes for checking session
for any request.Steps:
1. Read session cookie sent from browser.
2. Read session cookie process proceeds with below step checks
(If any one step fails below, it results in create one session
cookie)
2a. Checks if session cookie is present
2b. Checks if it is a valid session cookie by using it's
decryption algorithm check
2c. If valid session, then check if …
It's migration time. There was another project that I use often
and was still in Launchpad. The Sample Employees Database is now on
GitHub, under the same license it had before (CC
A-SA 3).
Figure 1 - Employees database
This database is interesting because it is not too small (like
Sakila) and not too big. It has enough data to allow you to test
in a non trivial way.
Installation and testInstalling the database is easy:
$ git clone https://github.com/datacharmer/test_db.git
$ cd test_db
$ mysql < employees.sql
INFO
CREATING DATABASE STRUCTURE
INFO
storage engine: InnoDB
INFO
LOADING departments
INFO
LOADING employees
INFO
LOADING dept_emp
INFO
LOADING dept_manager
INFO
LOADING titles
INFO …[Read more]
Benchmark for NVMFS (supports atomic writes ,so we can close double-write option on specific MySQL version )
tips: some Flash-based cards could support large block map , the main idea is to avoid fractured page writes.
Percona’s CTO Vadim Tkachenko wrote a response to my Galera Snapshot Isolation post last week. I think Tkachenko may have misunderstood some of my results, and I’d like to clear those up now. I’ve ported the MariaDB tests to Percona XtraDB Cluster, and would like to confirm that using exclusive write locks on all reads, as Tkachenko recommends, can recover serializable histories. Finally, we’ll address Percona’s documentation.
I didn’t use the default isolation levels
But there I need to add quite IMPORTANT addition: it may leave data in inconsistent state if you use SPECIAL TYPE of transactions in default isolation levels that Aphyr uses in his test.
My tests did not use the default isolation …
[Read more]