Introduction: where we standPrevious episodes:

• MySQL replication monitoring 101

MySQL replication in action - Part 1: GTID & Co
In the latest releases of MySQL and MariaDB we have seen several replication improvements. One of the most exciting additions is the ability to enhance basic replication with multiple sources. Those who have used replication for a while should remember that one of the tenets of the “old” replication was that a slave couldn’t have more than one master. This was The Law and there was no escape ... until now. The only way to work around that prohibition was to use circular replication, also known as …

In the theoretical part of this series, we have seen the basics of monitoring. In that article, though, we have barely mentioned the new tools available in MySQL 5.7 and MariaDB 10. Let’s start from something that has the potential of dramatically changing replication as we know it.
Crash-safe tables and Global transaction identifiers in MySQL 5.6 and 5.7Global transaction identifiers (GTID) is a feature that has been in my wish list for long time, since the times I was working with the MySQL team. By the time I left Oracle, this feature was not even in the plans.
When MySQL 5.6 was first disclosed, the biggest improvement for replication was the introduction of crash-safe tables (see Status persistence in …

The latest MySQL Sandbox, version 3.0.66 is out. It has a few new features (as always, when I find myself doing the same thing many times, I script it) and improved support for latest releases of MySQL. You can now install, among other versions, MySQL 5.7.8 and MariaDB 10.1.x

Some notable additions in this release are in the scripts that are created and customized for each sandbox. There are many of them and when one more arrives, it's easy to overlook it. So, here are the new arrivals.



./show_binlog
When I am troubleshooting replication behavior, I often need to inspect the latest binary log. The sandbox has a shortcut that gives me the right version of mysqlbinlog for the deployment:

Years ago I pursued my interest in InnoDB’s architecture and design, and became impressed with its sophistication. Another way to say it is that InnoDB is complicated, as are all MVCC databases. However, InnoDB manages to hide the bulk of its complexity entirely from most users.

I decided to at least outline a book on InnoDB. After researching it for a while, it became clear that it would need to be a series of books in multiple volumes, with somewhere between 1000 and 2000 pages total.

At one time I actually understood a lot of this material, but I have forgotten most of it now.

I did not begin writing. Although it is incomplete, outdated, and in some cases wrong, I share the outline here in case anyone is interested. It might be of particular interest to someone who thinks it’s an easy task to write a new …

This is a maintenance release which contains mainly bugfixes.

Get it from the download page.



Changelog:
* Bugfix: Crash in foreign key dropdown editor
* Bugfix: Crash when killing processes on very long running servers
* Bugfix: SQL error when accessing UUID and JSON columns in PostgreSQL via SUBSTR
* Bugfix: MSSQL: Prefer "schema.table" quoting over "schema"."table" when renaming a table
* Bugfix: Fix column type converted to locale string format by String.ToUpper in TDBConnection.GetCreateCode - prefer String.ToUpperInvariant instead, to avoid funny characters in data types
* Bugfix: MSSQL: Do not pass "Database=xyz" to connection string if database(s) setting contains more than one …

This is a maintenance release which contains mainly bugfixes.

Get it from the download page.



Changelog:
* Bugfix: Crash in foreign key dropdown editor
* Bugfix: Crash when killing processes on very long running servers
* Bugfix: SQL error when accessing UUID and JSON columns in PostgreSQL via SUBSTR
* Bugfix: MSSQL: Prefer "schema.table" quoting over "schema"."table" when renaming a table
* Bugfix: Fix column type converted to locale string format by String.ToUpper in TDBConnection.GetCreateCode - prefer String.ToUpperInvariant instead, to avoid funny characters in data types
* Bugfix: MSSQL: Do not pass "Database=xyz" to connection string if database(s) setting contains more than …

Introduction

A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table. The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. The purpose of the foreign key is to identify a particular row of the referenced table. Therefore, it is required that the foreign key is equal to the candidate key in some row of the primary table, or else have no value (the NULL value). This is called a referential integrity constraint between the two tables. Because violations of these constraints can be the source of many database problems, most database management systems provide mechanisms to ensure that every non-null foreign key corresponds to a row of the referenced table. Consider following simple example:

create table parent (
    id int not null primary key,
    name char(80)
) …

During the last couple of months I have been involved in an unusually high amount of performance audits for e-commerce applications running with Magento. And although the systems were quite different, they also had one thing in common: the MySQL query cache was very useful. That was counter-intuitive for me as I’ve always expected the query cache to be such a bottleneck that response time is better when the query cache is turned off no matter what. That lead me to run a few experiments to better understand when the query cache can be helpful.

Some context

The query cache is well known for its contentions: a global mutex has to be acquired for any read or write operation, which means that any access is serialized. This was not an issue 15 years ago, but with today’s multi-core servers, such serialization is the best way to kill performance.

However from a performance …

Hi all, it is time again to do another preview release of MySQL Group Replication, the plugin that brings multi-master update everywhere to MySQL, like we described in Hello World post.

We are very proud to do the third preview release of MySQL Group Replication, which introduces new exciting features, please enjoy the highlights!…

Taxonomy upgrade extras:  mysql performance monitor monitoring fpmmm maas performance monitor mpm

FromDual has the pleasure to announce the release of the new version 0.10.5 of its popular Database Performance Monitor for MySQL, MariaDB, Galera Cluster and Percona Server fpmmm.

You can download …