It’s been a while since I wrote about ClickHouse, there are a lot of new features that are worth mentioning, and for this, I recommend to follow the Altinity Blog but today I want to look at the improved integration of ClickHouse and MySQL.

There are two features:

1. Using MySQL protocol and MySQL client to connect to ClickHouse
2. Use MySQL tables to select and join with ClickHouse tables

Using MySQL Protocol

By enabling MySQL protocol in ClickHouse server, you will allow for the MySQL command line tool or applications that typically connect to MySQL to connect to ClickHouse and execute queries.

With this, keep in mind:

• It does not automatically allow you to use MySQL SQL syntax, you still need to write queries in ClickHouse-dialect.
• The same issue with datatypes. ClickHouse uses Int32/Int64 …

Understanding how MySQL handles connections and Troubleshooting MySQL error 1040 – Too many connections! How to interpret “MySQL error 1040 – Too many connections ! ” ?

When a client tries to log into MySQL it may sometimes be rejected and receive an error message saying that there are “too many connections“. This means that the maximum number of clients that may be connected to the server has been reached. Either the client will have to wait for another client to log off, or the administrator will have to increase the maximum number of connections allowed.

Information about connections to a server can be found using the SHOW STATUS statement:

SHOW STATUS LIKE 'max_used_connections';

Prerequisite – Few points to remember before working or troubleshooting MySQL ” Too many connections ! ” error

1. MySQL does not have it’s own thread handling mechanism / …

Last week I completed the Continuent Tungsten Solutions Training in London!

I spent two full days with eight of our customers and our host Chris Parker, one of Continuent’s Customer Success Directors, listening and learning, doing exercises, and getting to know a range of DBAs and System Engineers working in industries like telecom and e-commerce!

Chris did an incredible job guiding us and fielding questions on MySQL database management with Tungsten Clustering – I feel so lucky I got to do this – it was so fun!!

First we went through an install of a simple three-node cluster using allotted AWS ec2 instances. We created the directories and database users and got the Tungsten …

Care to give some detail about the usecase for a single transaction affecting 9 GB of data? Apart from backup restoration, that seems quite an anti-pattern…

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Recently I had the discussion with one of my colleague about the impact of MySQL binary logs . It was a nice discussion and triggered me further to benchmark the MySQL with/without binary logs . The result is amazing

Server configuration :

• 4 CPU
• 8 GB RAM
• 100 GB SSD

MySQL version : 8.0.19

I have conducted the test with a bulk transaction . It is a single thread INSERT with 9.5 GB of data .

Test 1 – With binary log :

screen 1 :

from the screen 1, I had split my terminal to three screens .

1st screen : I have triggered the bulk INSERT

2nd screen : The INSERT has started to execute and in executing state .

3rd screen : You can see the individual table-space file ( .ibd ) keep growing ( 5.6 GB ) on …

• In-built columnar storage engine that works next to Innodb on the same DB server.
• Materialized views - async and semi-immediate
• Recommended indexes based on query usage
• Rename CREATE PROCEDURE to CREATE DATABASE API. Yes, really.. just rename it.

INTERVIEW: Bernd Ocklin at Pre FOSDEM MySQL Day 2020 in Brussels
Interview

I have been considering this for a while, but the 2019 edition of the MySQL Community Awards will be the final year. Over the past couple of years, the Percona Live conference has been expanding well beyond the walls of MySQL. There doesn’t seem to be an obvious event to hold the awards at, where there is both a large number of MySQL community members attending and the winners of the awards are also present.

The beauty of these awards was that there was no corporate entity involved – they were completely from the people and for the people. I was always really happy to give out an award to people that may not always be recognized and to celebrate what they had done.

The awards have been given out for 15 years now and they were picked up by the community from MySQL AB after 2009. I only managed the awards for a few years of the 15 total years, and before me — it was Shlomi Noach, and before him — Henrik Ingo. For a bunch of …

A sold out, two-day event with over 30 sessions on various aspects of MySQL is a tough thing to organize and accomplish. But the MySQL pre-FOSDEM Days was an amazing success. If you missed this event then you really missed two full days of presentations by MySQL engineers and subject matter experts from the MySQL Community. 


It all started on Thursday January 30th with Geir Hoydalsvik talking about Simplifying MySQL which not a simple talk.  Big efforts are being made to clean up and modernize the MySQL Server Core code.  Work is being undertaken to change to a Volcano Model for extended flexibility. 

This was followed by Kenny Gryp showing how the new InnoDB Replica Set. Previously it was easier to setup InnoDB Cluster Replication than simple …

i was working on some example code for using check constraints and was fairly happy with my first bit of of code.

CREATE TABLE c1 (x INT 
                   CONSTRAINT x_gt_0 CHECK (x > 0)
);

it worked well and did what I wanted which was to reject data where the value for x was not one or greater. MySQL has allowed you to have constraint checks for many years but they only came to life in 8.0.16.  Before that version the checks were simply ignored.

So I was writing some more demo code and smacked into what I thought was an odd error.

CREATE TABLE c2 (x INT 
                   CONSTRAINT x_gt_0 CHECK (x > 0), 
                   CONSTRAINT …