Thanks to the great work and hosting by Marcus Popp anybody can test out the SQL syntax of MySQL 8.0.0 using db4free without installing anything. If you want a minimal install Giuseppe Maxia provides docker minimal images of 5.0+ versions …[Read more]
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A few weeks ago, I wrote a blog post explaining how sketch sampling methods can be employed to achieve fast 30-day data visibility for monitoring users. The problem we faced was that with that standard of retention, we’ve frequently seen systems that involve nearly a million query samples in a 30-day window, meaning that special solutions are needed in order to avoid overloading users’ browsers.
The solution we’ve found lies in a hash ordering that's proven to be both surprisingly simple and efficient. In this Part 2 post, I’ll look at why it works so well.
Ordering with a Hash
VividCortex’s query samples are stored in MySQL tables. The simplified schema definition looks like this:
Friday afternoon is always ideal for a quick look at the early quality of MySQL 8.0! Last Friday, I did just that.
If you haven’t heard the news yet, MySQL 8.0 DMR is available for download on mysql.com!
Tools to the ready: pquery2, updated 8.0 compatible scripts in Percona-qa and some advanced regex to wade through the many cores generated by the test run. For those of you who know and use pquery-run.sh, this should mean a lot!
[09:41:50]  ====== TRIAL …[Read more]
(Almost) another new year by Jewish calendar. What do I wish for the following year?
- World peace
- Good health to all
- Relaxed GTID constraints
I'm still not using GTID, and still see operational issues with
working with GTID. As a latest example, our new schema migration
solution, gh-ost, allows us to test migrations in production, on
replicas. The GTID catch?
gh-ost has to write
something to the binary log. Thus, it "corrupts" the replica with
a bogus GTID entry that will never be met in another server, thus
making said replica unsafe to promote. We can work around this,
I understand the idea and need for the
Set. It will certainly come in handy with
multi-writer InnoDB Cluster. However for most use cases GTID
poses a burden. The reason is that our topologies are imperfect,
and we as humans are imperfect, and operations are …
Codership’s Galera Cluster Best Practices Webinar for MySQL DBAs and DevOps Part One is now available to watch here
db4free.net was born in 2005 (which makes it older than Twitter or Google Chrome) when MySQL 5.0 was in early development. 11 years went by but one thing always remained the same: the 5 in MySQL’s major version number. MySQL versions went from 5.0 to 5.1 to 5.5, 5.6 and recently to 5.7. There was always this 5.something.
While this 5 will stay around for a bit longer, it is not alone anymore.
Now there is a duplicate of the db4free.net website at
where you can create a database on a newly set up MySQL 8.0 server!
MySQL 8.0 is in very early development, the first Development Milestone Release (MySQL 8.0.0 DMR) has just been released on September, 12. It will take several months until there will be a final release.
db4free.net makes it easy to try new features early. The …[Read more]
In a previous blog post we discussed several approaches to sharding. The most flexible one, sharding using metadata, is also the most complex one to implement. You need to design the meta-database, and build high availability not only for your application data but also for the metadata. On top of that, you need to design your application so it will be aware of the complex database infrastructure beneath - it has to query metadata first and then it has to be directed to a correct shard to read or write data. You will also have to build tools to manage and maintain the metadata. Migrating data requires caution so it has to be done carefully. You also have to make sure that any operations on the production databases are mirrored in the metadata. For instance, have you taken a slave out of rotation? This should be reflected in the metadata. Have you added a new …[Read more]
It is well known that replica servers in a master/slave configuration, to avoid breaking replication due to duplicate keys, missing rows or other similar issues, should not receive write queries. It’s a good practice to set
on slave servers to prevent any (accidental) writes. Servers acting as replicas will NOT be in read-only mode automatically by default.
has an historical issue: users with the SUPER privilege can override the setting and could still run DML queries. Since Percona Server 5.6.21 and MySQL 5.7.8, however, you can use the
feature to extend the
read_only …[Read more]
One of the main tasks that any DBA has to deal with is certainly
data retention. Especially when your developers like to store
logging and tracking information inside the database. This is not
something that I would recommend (don't try it at home!) but when
you're late to the party (read: someone had taken this path
before you joined) , then you'll have to live with it.
Data retention in MySQL is usually applied by partitioning the table by RANGE on a selected column, usually containing the row creation timestamp. New partitions are created in advance for the coming days or weeks or months, and a script is used that will run nightly and drop partitions that are older than a set retention.
There are many tools that can be used to automate data retention; I have chosen the excellent pdb-parted, a nice and cozy perl script that you can find in the PalominoDB repository on GitHub (since PalominoDB is no longer in existence, …
A new Group Replication plugin labs release has came out, a little over a week ago. Exciting news! This shows that the team has been working hard to shape up the plugin so that it meets the required feature set, performance and quality standards to be released as GA.…
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