The latest from the MySQL community

In this blog I will go through a number of popular applications that use
NDB Cluster 8.0 and also how these applications have developed over the
years.

There is a presentation at slideshare.net accompanying this blog.

The first major NDB development project was to build a prototype of a
number portability application together with a swedish telecom provider.
The aim of this prototype was to show how one could build advanced
telecom applications and manage it through standardised interfaces.
The challenge here was that the telecom applications have stringent
requirement, both on uptime and on latency. If the database access
took too long time the telecom applications would suffer from
abandoned calls and other problems. Obviously the uptime of the …

It used to be the case where, in order to actually process data retrieved from the database using Connector/Node.js, you would have to resort to an API that required the use of both JavaScript callbacks and Promises. This was meant to provide more flexibility and control to the application developer and at the same time decrease the chance of buffering data unnecessarily. However this wasn’t useful for 99% of the use-cases and made simple tasks a little bit cumbersome. Also, the fact that it required using two different asynchronous constructs made it a little bit harder to grasp.

To make matters worse, in order to consume operational metadata about the columns in the result set, you would have to provide an …

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In this post I’ll expand on the subject of my MySQL pre-FOSDEM talk: what dbadmins need to know and do, when upgrading from MySQL 5.7 to 8.0.

I’ve already published two posts on two specific issues; in this article, I’ll give the complete picture.

As usual, I’ll use this post to introduce tooling concepts that may be useful in generic system administration.

The presentation code is hosted on a GitHub repository (including the …

Recently one of our client approach Mydbops with Query slowness on a MySQL environment . They deployed the new code for generate the huge reports for the year end analytics data . After the deployment the queries were extremely slow and they struggled lot , then they approached us for the solution. After the analysis, their OLAP database as expected it was IO bound with 100% disk IOPS utilised during the report generation. So, the queries were starving for the Disk IO slows the process .

Problem statement :

• Reports are majorly focused on two larger log tables ( emp_Report_model , emp_details ) .
• The report generator (procedure) is using the count(*) statement to stimulate the aggregated data on each call. It is required for their business purpose .
• Count(*) is terribly slow in MySQL ( Using MySQL 5.7 ) as it …

Galera is the best solution for High Availability, It is being used by many peoples world wide . Galera is doing synchronous replication ( really it is Certification based replication ) to keep update the data on group nodes . In this blog I have explained about “How the Galera replication works?” . For the better understanding, I have made an architecture diagram to describe the replication flow . I have also provided the explanation for the key words which has used in the architecture diagram .

Architecture flow Diagram :

What is writeset ?

Writeset contains all changes made to the database by the transaction and append_key of the changed rows .

What is append_key ?

Append_key registers the key of the changed data by the transaction. The key for rows can be represented in three parts as DATABASE NAME, TABLE NAME, PRIMARY KEY . …

In this blog I am going to go through the most important requirements that
NDB Cluster 8.0 is based on. I am going to also list a number of consequences
these requirements have on the product and what it supports.

One slideshare.net I uploaded a presentation of the NDB Cluster 8.0
requirements. In this blog and several accompanying I am going to present the
reasoning that these requirements led to in terms of software architecture, data
structures and so forth.

The requirements on NDB Cluster 8.0 is the following:

1) Unavailability of less than 30 seconds per year (Class 6 Availability)
2) Predictable latency
3) Transparent Distribution and Replication
4) Write and Read Scalability
5) Highest availability even with 2 replicas
6) …

NDB Cluster was originally developed for Network DataBases in the telecom
network. I worked in a EU project between 1991 and 1995 that focused on
developing a pre-standardisation effort on UMTS that later became standardised
under the term 3G. I worked in a part of the project where we focused on
simulating the network traffic in such a 3G network. I was focusing my attention
especially on the requirements that this created on a network database
in the telecom network.

In the same time period I also dived deeply into research literatures about DBMS
implementation.

The following requirements from the 3G studies emerged as the most important:

1) Class 5 Availability (less than 5 minutes of unavailability per year)
2) High Write Scalability as well as High Read Scalability
3) Predictable latency down to milliseconds
4) Efficient API …

The requirements on Class 5 availability and immediate failover had two important
consequences for NDB Cluster. The first is that we wanted a fail-fast architecture.
Thus as soon as we have any kind of inconsistency in our internal data structures we
immediately fail and rely on the failover and recovery mechanisms to make the failure
almost unnoticable. The second is that we opted for a shared nothing model where all
replicas are able to take over immediately.

The shared disk model requires replay of the REDO log before failover is completed
and this can be made fast, but not immediate. In addition as one quickly understands
with the shared disk model is that it relies on an underlying shared nothing storage
service. The shared disk implementation can never be more available than the
underlying shared nothing storage service.

Thus it is actually possible to …

A number of developments was especially important in influencing the development
of NDB Cluster. I was working at Ericsson, so when I didn't work on DBMS research
I was deeply involved in prototyping the next generation telecom switches. I was the
lead architect in a project that we called AXE VM. AXE was the cash cow of Ericsson
in those days. It used an in-house developed CPU called APZ. I was involved in some
considerations into how to develop a new generation of the next generation APZ in the
early 1990s. However I felt that the decided architecture didn't make use of modern
ideas on CPU development. This opened for the possibility to use a commercial CPU
to build a virtual machine for APZ. The next APZ project opted for a development
based on the ideas from AXE VM at the end of the 1990s. I did however at this time
focus my full attention to development of NDB Cluster.
…