ProxySQL is an open-source MySQL proxy server, meaning it serves as an intermediary between a MySQL server and the applications that access its databases. ProxySQL can improve performance by distributing traffic among a pool of multiple database servers.

Consider 2 slaves are routed under Proxysql , In any one of the slave, if the replication is broken, we could still see the traffic routing to the broken replication slave. We can make Proxy to not send traffic to broken replication slave, by setting appropriate value to the variable mysql-monitor_slave_lag_when_null

…

Recently, while doing a test process to examine resource usage and the time required to alter the table using pt-osc, it leads to a loss of triggers even though the –preserve-triggers option is specified. I made the decision to recreate the identical circumstance so that everyone could see it.

Test environment : 

OS: Amazon Linux 2

MySQL version: 5.7.40

pt-online-schema-change version: 3.1.0

Before digging deeper, we must first obtain the whole picture. Here is an illustration of the table’s structure.

Table structure:

MySQL 8.0.30 was released on 26-07-2022. It has a good list of features.

• Generated Invisible Primary Key
• Dynamic Redo log Sizing
• Instruments to monitor group replication memory
• Support for Ubuntu 22.04

A most notable feature for Database Administrators and database reliability engineers is Dynamic redo logging.

The more widely adopted open-source backup tool is Xtrabackup. The change in the redo log design has affected this hot backup tool.

2022-10-04T18:40:08.211998+05:30 0 [Note] [MY-011825] [Xtrabackup] recognized server arguments: --datadir=/var/lib/mysql 
2022-10-04T18:40:08.212264+05:30 0 [Note] [MY-011825] [Xtrabackup] recognized client arguments: …

Mydumper supports streaming of backups right from version 0.11.3 and the latest version Mydumper 0.12.3 it enabled its support for compressed streaming backup. This was the most awaited feature added to Mydumper, making it a more powerful tool for data migration to RDS or Cloud.

If you are hearing mydumper for the first time, then let’s have a quick catch-up on what Mydumper is and what it does exactly.

Mydumper is a multithread logical backup and restores tool for MySQL and its forks. To know more you can refer to our previous blogs/presentations below.

• https://mydbops.wordpress.com/2016/01/31/faster-logical-backup-with-mydumper/
• …

As a Database Engineer, One of the biggest challenges in day-to-day activity is performing DDL on high-traffic and transaction-intensive tables. It will become overhead when handling a large number of servers/shards.

As a standard process, we will first deploy the changes in DEV and QA before deploying them in production.

In the sharded environment, It will become a heavy overhead to maintain the schema changes in DEV, QA, and PROD servers. Since we will have multiple servers in the sharding.

To overcome this deployment supervision, the Skeema tool will help to deploy the changes in QA, DEV, and PROD in a safe and parallel ( for Shards ) as well.

This blog focuses on the basic operation of Skeema, will have a series of blogs on Skeema

1. About the …

The following is a short HOWTO about deployment and use of Benchmark-kit (BMK-kit). The main idea of this kit is to simplify your life in running various MySQL benchmark workloads with less blood and minimal potential errors.

Generally as simple as the following :

$ bash /BMK/sb_exec/sb11-Prepare_50M_8tab-InnoDB.sh 32   # prepare data

$ for users in 1 2 4 8 16 32 64 128 256 512 1024 2048
do   
  # run OLTP_RW for 5min each load level..
  bash /BMK/sb_exec/sb11-OLTP_RW_50M_8tab-uniform-ps-trx.sh $users 300
  sleep 15
done

the latest public online version of the following HOWTO is always available from here : http://dimitrik.free.fr/blog/posts/mysql-perf-bmk-kit.html

Read more... (45 min remaining to read)

To copy the data of the particular column of the table to another table/server, We have an option to export the data as CSV and import the data back to a different table. But when the table size is large and we need to copy the data only for the required data to the target table will cause the load in the server since the table scanning is huge.

To overcome this, we have the pt-archiver copy the data from the source table to the destination as a whole or only for required columns. And also we can do this in a controlled manner as well. So there will be no performance impact even on the production time.

Source table structure :

mysql> show create table source\G
*************************** 1. row ***************************
       Table: source
Create Table: CREATE TABLE `source` (
  `id` int unsigned NOT NULL …

While exporting the table with MySQL native utility, we don’t have any control on the process, and also there will be no progress update as well on the process completion. So when exporting the larger table will consume high resource utilization and also the disk space usage will also be high.

MySQL shell utility will make the process easier. It will export the table and we can import the data back with a parallel thread and also will provide the current progress status on export/import progress.

util.exportTable() utility was introduced in Shell – 8.0.22 version, will export the data in a controlled manner. We can store the data in either local or Cloud Infrastructure Object Storage bucket as well.

We will see about the compression ratio along with the time taken for native MySQL vs Shell utility

Feature :

• Compression
• Progress status
• Supported output …

We all tried various alternative methods for modifying the table structure, but pt-online-schema-change (pt-osc) is the most convenient and preferred method for performing the alter online. It has more granular control too. But it may lead to data loss if proper precautionary steps are not taken care of.

In this blog, we are going to modify a column to a unique key using pt-osc, below I have shared the table structure.

mysql> show create table test\G
* 1. row *
Table: test
Create Table: CREATE TABLE test (
Personid int(11) NOT NULL AUTO_INCREMENT,
LastName varchar(255) NOT NULL,
FirstName varchar(255) DEFAULT NULL,
Age int(11) DEFAULT NULL,
PRIMARY KEY (Personid)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

I have inserted the data of 1000 rows using …

(based on a conversation with a colleague, and a bit of Twitter)

A Conundrum

A developer colleague paged me with this:

mysql> select
UNIX_TIMESTAMP("2021-03-26 03:07:00" + INTERVAL 2 YEAR) -
UNIX_TIMESTAMP("2021-03-26 02:07:00" + INTERVAL 2 YEAR) as delta\G
delta: 420

It is obviously wrong, and weirdly so. It only works for “2 year”, not with other values:

mysql> select
UNIX_TIMESTAMP("2021-03-26 03:07:00" + INTERVAL 1-11 year_month) -
UNIX_TIMESTAMP("2021-03-26 02:07:00" + INTERVAL 1-11 year_month) as delta\G
delta: 3600

mysql> select
UNIX_TIMESTAMP("2021-03-26 03:07:00" + INTERVAL 1-12 year_month) -
UNIX_TIMESTAMP("2021-03-26 02:07:00" + INTERVAL 1-12 year_month) as delta\G
delta: 3600

mysql> select
UNIX_TIMESTAMP("2021-03-26 03:07:00" + INTERVAL 1-13 year_month) -
UNIX_TIMESTAMP("2021-03-26 02:07:00" + INTERVAL 1-13 …