In one of the latest post, I discussed how to transform a large MySQL table to JSON using Apache Spark. Well, that approach works for any tables with any volume. But it’s an overkill for simple and small tables. The good news is MySQL by default has a feature for …

The post Export MySQL query results as JSON appeared first on Geeky Hacker.

Then secretary of Defense Donald Rumsfeld popularized the terms: “known knowns”, “known unknowns”, and “unknown unknowns.” With the ever-increasing number of data breaches and vulnerabilities, database operation teams have to account for every possibility. Visualizing your audit data allows you to look for the “unknowns”, those access patterns or connections that you’d otherwise overlook.

Although enabling an audit log and shipping it off to a vault may meet security and regulatory requirements, you will lose an important opportunity to protect your customer and employee information.

The following dashboard demonstrates the type of information that audit logs can reveal:

• Who is connecting to my database (IP address, location, username..)
• Who is trying to connect to my database but getting access errors?
• Which tables are being accessed and by whom?
…

This blog post illustrates ” How to setup SSL enabled replication”

By default, mysql package installation creates SSL file in the data directory at the time of installation. If you would like to use different self-signed certificates then create them as described here.

Add SSL setting to my.cnf on all servers.

ssl=on
ssl-ca=/etc/sslcerts/ca.pem
ssl-cert=/etc/sslcerts/server-cert.pem
ssl-key=/etc/sslcerts/server-key.pem

Restart mysql server and verify the settings.

Example: client connections using SSL

#mysql -urpluser -p -P22403 --host 127.0.0.1 --ssl-cert=/etc/sslcerts/client-cert.pem --ssl-key=/etc/sslcerts/client-key.pem -e '\s'
Enter password:
--------------

Connection id: 5
Current database:
Current user: rpluser@localhost
SSL: Cipher in use is DHE-RSA-AES256-SHA
Current …

In a MySQL master-slave high availability (HA) setup, it is important to continuously monitor the health of the master and slave servers so you can detect potential issues and take corrective actions. In this blog post, we explain some basic health checks you can do on your MySQL master and slave nodes to ensure your setup is healthy. The monitoring program or script must alert the high availability framework in case any of the health checks fails, enabling the high availability framework to take corrective actions in order to ensure service availability.

MySQL Master Server Health Checks

We recommended that your MySQL master monitoring program or scripts runs at frequent intervals. Assuming that the monitoring script is running on the same server as your …

Introduction In this article, we are going to see how the SQL EXISTS operator works and when you should use it. Although the EXISTS operator has been available since SQL:86, the very first edition of the SQL Standard, I found that there are still many application developers who don’t realize how powerful SQL subquery expressions really are when it comes to filtering a given table based on a condition evaluated on a different table. Database table model Let’s assume we have the following two tables in our database, that form a one-to-many... Read More

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Monitoring your MySQL database performance in real-time helps you immediately identify problems and other factors that could be causing issues now or in the future. It’s also a good way to determine which components of the database can be enhanced or optimized to increase your efficiency and performance. This is usually done through monitoring software and tools either built-in to the database management software or installed from third-party providers.

Prometheus is an open-source software application used for event monitoring and alerting. It can be used along with a visualization tool like Grafana to easily create and edit dashboards, query, visualize, alert on, and understand your metrics. ScaleGrid provides full admin access to your MySQL deployments – this makes it …

Andreas Andreakis, Ioannis Papapanagiotou

Overview

Change-Data-Capture (CDC) allows capturing committed changes from a database in real-time and propagating those changes to downstream consumers [1][2]. CDC is becoming increasingly popular for use cases that require keeping multiple heterogeneous datastores in sync (like MySQL and ElasticSearch) and addresses challenges that exist with traditional techniques like dual-writes and distributed transactions [3][4].

In databases like MySQL and PostgreSQL, transaction logs are the source of CDC events. As transaction logs typically have limited retention, they aren’t guaranteed to contain the full history of changes. Therefore, dumps are needed to capture the full state of a source. There are several open source CDC projects, …

In a MySQL 5.7 master-slave setup that uses the default semisynchronous replication setting for rpl_semi_sync_master_wait_point, a crash of the master and failover to the slave is considered to be lossless. However, when the crashed master comes back, you may find that it has transactions that are not present in the current master (which was previously a slave). This behavior may be puzzling, given that semisynchronous replication is supposed to be lossless, but this is actually an expected behavior in MySQL. Why exactly this happens is explained in full detail in the …

By having appropriate indexes on your MySQL tables, you can greatly enhance the performance of SELECT queries. But, did you know that adding indexes to your tables in itself is an expensive operation, and may take a long time to complete depending on the size of your tables? During this time, you are also likely to experience a degraded performance of queries as your system resources are busy in index-creation work as well. In this blog post, we discuss an approach to optimize the MySQL index creation process in such a way that your regular workload is not impacted.

MySQL Rolling Index Creation

We call this approach a ‘Rolling Index Creation’ - if you have a MySQL master-slave replica set, you can create the index one node at a time in a rolling fashion. You should create the index only on the slave nodes so the master’s …

Introduction In this article, we are going to see how a deadlock can occur in a relational database system, and how Oracle, SQL Server, PostgreSQL, or MySQL recover from a deadlock situation. Database locking Relational database systems use various locks to guarantee transaction ACID properties. For instance, no matter what relational database system you are using, locks will always be acquired when modifying (e.g., UPDATE or DELETE) a certain table record. Without locking a row that was modified by a currently running transaction, Atomicity would be compromised. Using locking for controlling access... Read More

The post A beginner’s guide to database deadlock appeared first on Vlad Mihalcea.