This tutorial shows how you can install Nginx on an Ubuntu 20.04 LTS server with PHP 7.4 support (through PHP-FPM) and MySQL support (LEMP = Linux + Nginx (pronounced "engine x") + MySQL + PHP).

In Percona’s Managed Services, we start up and shut down MySQL servers all the time.  Over the years, we’ve seen various issues occur due to the way servers are shut down.  No matter if it is a situation where unexpected errors appear in the log or you’re stuck waiting for hours for a server to finishing shut down… Here are some steps we can take to minimize any trouble and prepare MySQL for shutdown.

This list of “super safe practices” was born from lessons we’ve learned in a wide variety of MySQL environments.

1. Stop Replication.

Under some (rare) circumstances, a slave may try to startup in the incorrect position. To help minimize this risk, stop the IO thread first so it’s not receiving new events.

STOP SLAVE IO_THREAD;

Wait for the SQL thread to apply all events, then stop it too.

SHOW SLAVE STATUS\G
STOP SLAVE SQL_THREAD;

This puts both of the …

On a busy server, the binary logs can end up being one of the largest contributors to amount of disk space used. That means higher I/O, larger backups (you are backing up your binary logs, right?), potentially more network traffic when replicas fetch the logs, and so on. In general, binary logs compress well, so it has been a long time wish for a feature that allowed you to compress the logs while MySQL are still using them. Starting from MySQL 8.0.20 that is now possible. I will take a look at the new feature in this post.

Configuration

The binary log compression feature is controlled by two variables, one for enabling the feature and another to specify the compression level. These are summarized in the below table.

Given a JSON object:
SET @j := '{"BOOSTER": 1, "RETRO": 2, "GUIDANCE": 0, "SURGEON": 1, "RECOVERY": 0}';

How do you find the keys which do NOT contain a value of 0?

A second approach to finding the non-0 values from a JSON object is to turn the keys and values into separate columns of a table. This is cleaner, but a little wordier.

We’ll get the keys in one table:

SELECT ord, keyname 
FROM JSON_TABLE(JSON_KEYS(@j), '$[*]' COLUMNS (
    ord FOR ORDINALITY,
    keyname VARCHAR(100) PATH '$')
) AS keyTable;
 +------+----------+
 | ord  | keyname  |
 +------+----------+
 |    1 | RETRO    |
 |    2 | BOOSTER  |
 |    3 | SURGEON  |
 |    4 | GUIDANCE |
 |    5 | RECOVERY |
 +------+----------+

And the values in a second table:

SELECT ord, …

As Alkin and Ramesh have shown us in their Testing Percona XtraDB Cluster 8.0 with DBdeployer post, it is now possible to easily deploy an environment to test the features provided by the brand new release of Percona XtraDB Cluster 8.0.

We have also worked on creating a testing environment available for those that use Vagrant instead. Be it that it’s what you are used to working with, or that you want a proper VM for each instance, in particular, you can use the following commands to easily deploy a three-node cluster.

Requirements

Vagrant runs in Linux, Mac OS, and Windows, you just need to have the packages installed. Visit …

Establishing a many-to-many relationship between the tables in a database is usually done for ensuring efficient data processing and data integrity, as well as for database normalization and data analysis tasks. Since relational databases don’t allow implementing a direct many-to-many relationship between two tables, handling that kind of relationship can be an intimidating task. In […]

On Monday April 27th, MySQL released a much-anticipated patch release 8.0.20. Along with many bug fixes and improvements, a new property was introduced – binlog-transaction-compression. During our own internal testing we have discovered an incompatibility with our Continuent Tungsten products when this property is enabled.

The newly-released binlog-transaction-compression feature is really interesting because it compresses transaction payloads before being written into the binary logs, which in turn reduces the disk space overhead required for storage. I’m sure many users will be keen to implement this, however at this time the use of binlog-transaction-compression=ON will prevent Replication from functioning correctly.

This …

On Monday April 27th, MySQL released a much anticipated patch release 8.0.20. Along with many bug fixes and improvements, a new property was introduced - binlog-transaction-compression. During our own testing we have discovered an incompatibility with this property. Read on for more information.

Tags:  MySQL MySQL 8 tungsten clustering tungsten replicator known issue

Given a JSON object:
SET @j := '{"BOOSTER": 1, "RETRO": 2, "GUIDANCE": 0, "SURGEON": 1, "RECOVERY": 0}';

How do you find the keys which do NOT contain a value of 0?

One approach is to find the keys which do match 0, and then remove them.

Sounds like JSON_SEARCH and JSON_REMOVE? But there’s a gotcha: JSON_SEARCH works only with strings. Ok, so we REPLACE(@j, ‘0’, ‘”0″‘) – but that doesn’t help, because JSON_REMOVE can’t accept an array of paths like JSON_SEARCH would return; it requires each path as a separate parameter.

Instead, JSON_MERGE_PATCH will suffice. It has the feature that values from the second parameter are preserved only if they are not NULL. So, the approach becomes turning the 0s into NULLs, and then merging that document into an empty one.

SELECT REPLACE(@j, 0, 'null') AS j; -- …

Use MySQL Enterprise Audut plugin to track data changes on specific tables. Scripts and documentation on github: https://github.com/wwwted/Database-change-tracking Tracked data (audit logs) can then be inserted into reporting db using parser scripts. Limitations:

• Changing tracking rules stopps all tracking for existing connections until the reconnect. This is a limitation in MySQL EE Audit filter handling.
• No filtering for different users, easy to implement if needed in change_tracking.sql SP (START/STOP).
• Only tracking INSERT/UPDATE/DELETE statements. Easy to modify if needed.

1 Enable tracking on target server …