This Log Buffer Edition covers some of the niftiest blog posts from Oracle, SQL Server and MySQL.
Oracle:
Recently we released an updated version of our Percona Toolkit with an important update for pt-online-schema-change if you use MySQL 5.6. A new parameter has been added, analyze-before-swap. What does it do? Let me explain it in more detail.
A bug not a bug
A customer contacted us because pt-online-schema-change caused hundred of queries to get stuck after the ALTER was done. All those queries were trying read from the altered table but for some reason the queries never finished. Of course, it caused downtime. The reason behind this is this “bug not a bug”:
http://bugs.mysql.com/bug.php?id=78289
As a summary, if you are running 5.6 with persistent stats enabled (which it is by default), the optimizer in some …
[Read more]And by MySQL Ecosystem here, I do not only include Oracle but also MariaDB.
So I am annoyed, not overly annoyed (probably also a little disappointed), but enough to do something about it (write this post). In the last days, two blog posts - relayed in social medias - were published by MySQL vendors (I am not linking to the posts, it is a waste of time for the reader - see below - and they can
The binary log contains “events” that describe database changes. On a basic installation with default options, it's not turned on. This log is essential for accommodating the possible following requirements:
Replication: the binary log on a master replication server provides a record of the data changes to be sent to slave servers. Point in Time recovery: allow to recover a database from a full
db4free.net finally runs MySQL 5.7 which was released on October 21.
Rather than upgrading the existing MySQL server I set up a new MySQL 5.7 server. This is cleaner and it helps to get rid of accounts which are no longer used.
For active users, the MySQL 5.6 server will stay online
until January 15, 2016.
You can access it on port 3307 (the new MySQL 5.7 server will again run on MySQL’s default port 3306).
Users who want to keep their data need to migrate it to the new server:
If you use the MySQL default client and …
[Read more]In the last couple of weeks, there have been a few blog posts about benchmarks comparing the performance of various versions of MySQL and variants such as MariaDB. There’s also been some analysis of the results using formal models such as Neil Gunther’s Universal Scalability Law.
What can the Universal Scalability Law (USL) teach us about the performance characteristics of these systems, as revealed by the benchmarks? To find out, I’ll examine one particular benchmark, MariaDB 10.1 and MySQL 5.7 performance on commodity hardware.
The context for this benchmark, in a nutshell, is that MySQL 5.7 was just released as GA, and the published performance results are spectacular, from the point of view of throughput on large servers. Although this is good, showing that MySQL can scale to do lots of work on large servers, the MariaDB …
[Read more]In the last couple of weeks, there have been a few blog posts about benchmarks comparing the performance of various versions of MySQL and variants such as MariaDB. There’s also been some analysis of the results using formal models such as Neil Gunther’s Universal Scalability Law.
What can the Universal Scalability Law (USL) teach us about the performance characteristics of these systems, as revealed by the benchmarks? To find out, I’ll examine one particular benchmark, MariaDB 10.1 and MySQL 5.7 performance on commodity hardware.
Many of my recent engagements have been all around strategy to
implement Real Time Big Data Analytics: Computing hardware
cost of extending a single table collection with MariaDB
and Parallel Query found in the Spider storage engine
to offload columnar MPP storage like InfiniDB or Vertica.
As of today Parallel Query is only available
from releases of MariaDB Spider supported by spiral arms. The
more efficient way to use parallel query with Spider can be done
on group by, and count queries that use a single
spider table. In such case Spider Engine will execute query
push down AKA map reduce.
Spider gets multiple levels of parallel execution for a single
partitioned tables.
First level is per backend server:
The way to actually tell spider to scan different backends in
concurrency is to set spider_sts_bg_mode=1
Other level is per …
The new Mydumper 0.9.1 version, which includes many new features and bug fixes, is now available. You can download the code from here.
A significant change included in this version now enables Mydumper to handle all schema objects!! So there is no longer a dependency on using mysqldump to ensure complex schemas are backed up alongside the data.
Let’s review some of the new features:
Full schema support for Mydumper/Myloader
Mydumper now takes care of backing up the schema, including Views and Merged tables. As a result, we now have these new associated options:
-d, --no-data Do not dump table data
-G, --triggers Dump triggers
-E, --events Dump events
-R, …
Nginx is well-known for its ability to act as a reverse-proxy with small memory footprint. It usually sits in the front-end web tier to redirect connections to available backend services, provided these passed some health checks. Using a reverse-proxy is common when you are running a critical application or service that requires high availability. It also distributes the load equally among the backend services.
Recently, nginx 1.9 introduced support for TCP load balancing - similar to what HAProxy is capable of. The one major drawback is that it does not support advanced backend health checks. This is required when running MySQL Galera Cluster, as we’ll explain in the next section. Note that this limitation is removed in the paid-only edition called NGINX Plus.
In this blog post, we are going to play around with nginx as a reverse-proxy for MySQL Galera Cluster services to achieve higher availability. We had a Galera cluster …
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