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ProxySQL 2.0.5 and proxysql-admin tool Now Available

ProxySQL 2.0.5, released by ProxySQL, is now available for download in the Percona Repository along with Percona’s proxysql-admin tool.

ProxySQL is a high-performance proxy, currently for MySQL and database servers in the MySQL ecosystem (like Percona Server for MySQL and MariaDB). It acts as an intermediary for client requests seeking resources from the database. René Cannaò created ProxySQL for DBAs as a means of solving complex replication topology issues.

This release includes ProxySQL 2.0.5 which fixes many bugs and introduces a number of features …

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SQL Check Constraint Example | Check Constraint In SQL Tutorial

SQL Check Constraint Example | Check Constraint In SQL Tutorial is today’s topic. Check constraint is used for specifying the predicate that every tuple must satisfy in a relation i.e. it is used for limiting the values that a column can hold in a relation. It is used for giving a condition to check the value to be entered into a record. If the condition results in false then that value will not be added to the record.

SQL Check Constraint

The CHECK constraint is used to limit the value range that can be placed in a column.

If you define a CHECK constraint on a single column it allows only certain values for this column.

If you define a CHECK constraint on a table it can limit the values in certain columns based on values in other columns in the row.

Some key points of SQL Check Constraint are following.

  1. Check constraint cannot be defined inside the …
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SQL String Functions Example | String Functions In SQL

SQL String Functions Example | String Functions In SQL is today’s topic. String functions are used for manipulating the strings. Here, in SQL, we provide the string as input and then after applying string functions desired manipulated string is obtained. Let’s discuss all the string functions with proper explanation and examples.

SQL String Functions

See the following String Functions.

#ASCII()

The ASCII function is used for finding the ascii value of the character i.e. the numeric value. If more than one character is inserted within the function then the leftmost character value will be displayed. Here, we are using SQL SELECT Statement.

#Syntax

SELECT ASCII('ab');

#Output

97

#CHAR_LENGTH()

The char_length() function is used for finding the length of a word.

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MySQL User Camp, Bangalore India, Aug 23, 2019
A small thing that can save a lot of mess, meet: SET PERSIST

To set correct system variable values is the essential step to get the correct server behavior against the workload.  

In MySQL we have many System variables that can be changed at runtime, most of them can be set at session or at global scope. 

To change the value of a system variable at global level in the past user need to have SUPER privileges. Once the system variable value is modified as global, the server will change his behavior for the session, and obviously as global scope. For instance, one of the most commonly adjusted variables is probably max_connections. If you have max_connection=100 in your my.cnf or as default value, and during the day as DBA you notice that the number of them is not enough, it is easy just to add new connections on the fly, the command:

SET GLOBAL MAX_CONNECTIONS=500;

Will do the work. But here is the issue. We had changed a GLOBAL value, that apply to the whole …

[Read more]
A small thing that can save a lot of mess, meet: SET PERSIST

To set correct system variable values is the essential step to get the correct server behavior against the workload.  

In MySQL we have many System variables that can be changed at runtime, most of them can be set at session or at global scope. 

To change the value of a system variable at global level in the past user need to have SUPER privileges. Once the system variable value is modified as global, the server will change his behavior for the session, and obviously as global scope. For instance, one of the most commonly adjusted variables is probably max_connections. If you have max_connection=100 in your my.cnf or as default value, and during the day as DBA you notice that the number of them is not enough, it is easy just to add new connections on the fly, the command:

SET GLOBAL MAX_CONNECTIONS=500;

Will do the work. But here is the issue. We had changed a GLOBAL value, that apply to the whole …

[Read more]
Fun with Bugs #88 - On MySQL Bug Reports I am Subscribed to, Part XXII

It's Saturday night. I have a week of vacation ahead that I am going to spend at home, working on things I usually do not have time for. I already did something useful (created a couple of test cases for MariaDB bugs here and there, among other things), so why not to get some fun and continue my previous review of recent interesting MySQL bug report...

So, here is the list of 15 more MySQL community bug reports that I've subscribed to back in May and June 2019:

  • Bug #95491 - "The unused wake up in simulator AIO of function reserve_slot". I am impressed by …
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Create Post-Mortem Reports from Notebook Templates, Export to PDF

We've released two enhancements to Notebooks that streamline collaborations to help you create post-mortem Notebooks more easily, and share them in a format that's easy for any audience to access. Both improvements are focused around how teams have told us they can get more value from Notebooks. Involving everyone in database performance is a key goal at VividCortex, so these capabilities were natural next steps for the popular Notebooks feature!

If you're not familiar with Notebooks yet, they're like a wiki built into VividCortex. Using the simple Markdown syntax, you and your team can collaborate on rich documents with headers, lists, tables, images, and—of course—embedded, live charts of any metrics, prebuilt charts, or custom charts in VividCortex. You can use them for documentation, runbooks, dashboards, post-mortems, and as scrapbooks for gathering information during an incident—among many other possible uses. Notebooks support …

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MySQL Memory Calculator

MySQL Memory Calculator

Check out the “MySQL Memory Calculator” added to my blog page, which will be helpful to calculate MySQL memory usage during tuning of MySQL memory parameters. https://www.abhinavbit.com/p/mysql-memory-calculator.html




Photo by Kelly Sikkema on Unsplash

Setting Up a Galera Cluster on Amazon AWS EC2

Through Amazon Web Services (AWS), you can create virtual servers (i.e., instances). You can install database and Galera software on them. In this article, we’ll create three nodes, the minimum recommended for a healthy cluster, and configure them to use Galera Cluster.

Incidentally, there is a more detailed version of this article in the Tutorial section of our Library.

Assumptions & Preparation

We’re assuming you have an AWS account and know the basics of the EC2 (Elastic Compute Cloud) platform.

To access the nodes, you’ll need an encryption key. Create a new one specifically for Galera, using a tool such as ssh-keygen. Add that key to AWS, under Key Pairs.

Creating AWS Instances

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