We saw yesterday that when an issue (like network splitting), it’s possible to remain with a partitioned cluster where none of the partition have quorum (majority of members). For more info read how to manage a split-brain situation.

If your read the previous article you notice the red warning about forcing the quorum. As an advice is never too much, let me write it down again here : “Be careful that the best practice is to shutdown the other nodes to avoid any kind of conflicts if they reappear during the process of forcing quorum“.

But if some network problem is happening it might not be possible to shutdown those other nodes. Would it be really bad ?

YES !

Split-Brain

Remember, we were in this situation:

We …

In this blog, I will provide answers to the Q & A for the MySQL 8.0 Architecture and Enhancement webinar.

First, I want to thank everybody for attending my April 9, 2019, webinar. The recording and slides are available here. Below is the list of your questions that I was unable to answer fully during the webinar.

Q: What kind of Encryption levels does MySQL 8.0 provide?

The MySQL data-at-rest encryption feature supports the Advanced Encryption Standard (AES) block-based encryption algorithm and aes_256_cbc encryption algorithm for data at rest is hard coded.

Q: At what frequency does the redo log buffer flush the changes to disk? When is the commit variable set to zero?

Here’s an …

MySQL InnoDB Cluster - HowTo #1 - Monitor your cluster

Q: How do I monitor the status & the configuration of my cluster?

A: Use status() or status({extended:true}) or status({queryMembers:true})?

Everywhere I go to present MySQL InnoDB Cluster, during the demo of creating a cluster, many people doesn’t understand why when I’ve 2 members, my cluster is not yet tolerant to any failure.

Indeed when you create a MySQL InnoDB Cluster, as soon as you have added your second instance, you can see in the status:

    "status": "OK_NO_TOLERANCE",      
    "statusText": "Cluster is NOT tolerant to any failures.",

Quorum

Why is that ? It’s because, to be part of primary partition (the partition that holds the service, the one having a Primary-Master in Single Primary Mode, the default mode), your partition must reach the majority of nodes (quorum). In MySQL InnoDB Cluster (and many other cluster solutions), to achieve quorum, the amount of members in a partition must be > (bigger) than 50%.

So when we have 2 nodes, if there is a network issue between the …

SQL Where Clause Example | SQL Where Query Tutorial is today’s topic. The WHERE clause is used to filter the database records. The WHERE clause is used to extract only those records that fulfill the specified condition. The SQL WHERE clause is used to specify the condition while fetching the data from a single table or by joining the multiple tables. If a given condition is satisfied, then only it returns the specific value from the table. You should use a WHERE clause to filter the records and fetching the necessary records.

SQL Where Clause Example

The WHERE clause is not only used in the SELECT statement; it is also used in an UPDATE, DELETE statement. The syntax of a SELECT statement with a WHERE clause is following.

SELECT column1, column2, columnN 
FROM table_name
WHERE [condition]

“SELECT column1, column2, column3 FROM tableName” is the standard …

In my previous post, some time ago, I wrote about the new cluster feature of ProxySQL. For that post, we were working with three nodes, now we’ll work with even more! If you’ve installed one ProxySQL per application instance and would like to work up to more, then this post is for you. If this is new to you, though, read my earlier post first for more context.

Check the image below to understand the structure of “one ProxySQL per application”. This means you have ProxySQL installed, and your application (Java, PHP, Apache server etc) in the same VM (virtual machine).

Having taken a look at that you probably have a few questions, such as:

• What happens if you have 20 nodes …

In MySQL, historically GROUP BY was used to provide sorting as well. If a query specified GROUP BY, the result was sorted as if ORDER BY was present in the query.

mysql-5.7> CREATE TABLE t (id INTEGER,  cnt INTEGER);
Query OK, 0 rows affected (0.03 sec)

mysql-5.7> INSERT INTO t VALUES (4,1),(3,2),(1,4),(2,2),(1,1),(1,5),(2,6),(2,1),(1,3),(3,4),(4,5),(3,6);
Query OK, 12 rows affected (0.02 sec)
Records: 12  Duplicates: 0  Warnings: 0

mysql-5.7> SELECT id, SUM(cnt) FROM t GROUP BY id;
+------+----------+
| id   | SUM(cnt) |
+------+----------+
|    1 |       13 |
|    2 |        9 |
|    3 |       12 |
|    4 |        6 |
+------+----------+
4 rows in set (0.00 sec)

MySQL here implicitly sorts the results from GROUP BY (i.e.…

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Throughout this tutorial, we'll be using PHP with React and Axios to create a simple REST API application with CRUD operations. In the backend we'll use PHP with a MySQL database.

The PHP backend will expose a set of RESTful API endpoints so we'll be using the Axios library for making Ajax calls from the React.js UI.

We'll also see how to handle forms in React and how to send multipart form data with Axios using FormData.

In this tutorial, we are going to integrate React with PHP using Babel in the browser and a <script> tag. As such, we'll serve the React application from PHP so we don't need to enable CORS in our server since both the backend and frontend are served from the same domain.

We'll see the other approach of using two separate servers for the frontend and backend apps in another tutorial which will use the create-react-app to create the React project.

Prerequisites

You must …

Please join Percona’s Product Manager, Michael Coburn, as he presents his talk Extending and Customizing Percona Monitoring and Management on April 10th, 2019 at 10:00 AM PDT (UTC-7) / 1:00 PM EDT (UTC-4).

Register Now

Do you already run stock PMM in your environment and want to learn how you extend the PMM platform? If so, come learn about:

1. Dashboard Customizations
* How to create a custom dashboard from existing graphs, or build Cross Server Dashboards
2. External Exporters – Monitor any service, anywhere!
* …

This post is for the backup script for MySQL database on Linux with mail. It’s a linux shell script for taking logical backup using mysqldump and sending status email. The…

The post MySQL backup shell script with status email first appeared on Change Is Inevitable.