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Displaying posts with tag: MySQL (reset)
MySQL 8.0: ひらがなカタカナを判別する日本語用Collation

以前の記事では、MySQL 8.0.1で導入された新しい 日本語のutf8bm4のCollation(文字照合順)について ご紹介しました。このcollation (utf8mb4_ja_0900_as_cs) は、CLDR 30で定義されたアクセント記号(清音濁音半濁音)ならびに大文字小文字(拗音促音など)を判別する実装となっています。

今日ご紹介するのはひらがなカタカナを判別できる新しい「かなセンシティブ」なCollation utf8mb4_ja_0900_as_cs_ksです。 …

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MySQL8.0: 日本語のutf8bm4のCollation(文字照合順)

MySQL 8.0.1では、utf8mb4の大文字小文字およびアクセント記号付きの文字を判別するas_cs collationに加えて、日本語用のCollation(文字照合順)を追加しました。


日本語に関する文字照合およびソートのルールは複雑です。日本語ではひらがな、カタカナ、漢字、アルファベット(ラテン文字)を混在させて利用しています。さらに、全角と半角が存在する文字もあります。では、‘あ’, ‘ア’, ‘a’, ‘ア’はどのようにソートされるのでしょうか?

Unicode照合アルゴリズム(UCA / Unicode Collation …

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How to backup MySQL 5.7

If you ever tried to backup MySQL 5.7 with Percona Xtrabackup that comes in percona-xtrabackup package most likely you got error message like this:

# innobackupex ./
170623 05:58:43 innobackupex: Starting the backup operation

IMPORTANT: Please check that the backup run completes successfully.
At the end of a successful backup run innobackupex
prints "completed OK!".

170623 05:58:44 version_check Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup' as 'dba' (using password: YES).
170623 05:58:44 version_check Connected to MySQL server
170623 05:58:44 version_check Executing a version check against the server...
170623 05:58:44 version_check Done.
170623 05:58:44 Connecting to MySQL server host: localhost, user: dba, password: set, port: not set, socket: not set
Error: Unsupported server version: '5.7.18-15'. Please report a bug at

This happens because …

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ClickHouse in a General Analytical Workload (Based on a Star Schema Benchmark)

In this blog post, we’ll look at how ClickHouse performs in a general analytical workload using the star schema benchmark test.

We have mentioned ClickHouse in some recent posts (ClickHouse: New Open Source Columnar Database, Column Store Database Benchmarks: MariaDB ColumnStore vs. Clickhouse vs. Apache Spark), where it showed excellent results. ClickHouse by itself seems to be event-oriented RDBMS, as its name suggests (clicks). Its primary purpose, using Yandex Metrica (the system similar to Google Analytics), also points to an event-based nature. We also can see there is …

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How to Install LAMP on Ubuntu 16.04

LAMP (Linux, Apache, MySQL, PHP) is a combination of open source software, typically installed on a server used for hosting dynamic websites and web applications. It includes the Linux operating system, the Apache web server, MySQL for data storage and management and PHP for handling the dynamic content. In this tutorial, we will go through a complete LAMP installation on a Ubuntu 16.04 based VPS. Requirements SSH access with root privileges to your server, as well as an Ubuntu 16.04 VPS is required for you to be able to complete all the steps in this tutorial. 1. Update your system […]

Linux perf and the CPU regression in MySQL 5.7

I used Linux perf to get more details on system performance while running the point-query test with modern sysbench. This is for an in-memory workload and part of my series on low-concurrency CPU regressions for bug 86215.


  • I have more explaining to do
  • The increase in instructions/query explains the decrease in queries/second from MySQL 5.6 to 5.7 to 8.0.


I tested MySQL using upstream 5.6.35, 5.7.17 and 8.0.1. For 8.0.1 I used the latin1 charset and latin1_swedish_ci collation. My servers are  …

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Protecting Data with Digital Signatures by Example using MySQL Enterprise Edition

Often databases contain data that needs to be proven as valid and authentic. We want to ensure that a known person or other sender (e.g. a trusted app) of the information can’t deny content, nor that the content can change without that person (senders) consent.…

Webinar Thursday June 22, 2017: Deploying MySQL in Production

Join Percona’s Senior Operations Engineer, Daniel Kowalewski as he presents Deploying MySQL in Production on Thursday, June 22, 2017 at 11:00 am PDT / 2:00 pm EDT (UTC-7).

Register Now  MySQL is famous for being something you can install and get going in less than five minutes in terms of development. But normally you want to run MySQL in production, and at scale. This requires some planning and knowledge. So why not learn the best practices around installation, configuration, deployment and backup?

This webinar is a soup-to-nuts talk that will have you going from zero to hero in no time. It includes discussion …

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The MySQL High Availability Landscape in 2017 (The Elders)

In this blog, we’ll look at different MySQL high availability options.

The dynamic MySQL ecosystem is rapidly evolving many technologies built around MySQL. This is especially true for the technologies involved with the high availability (HA) aspects of MySQL. When I joined Percona back in 2009, some of these HA technologies were very popular – but have since been almost forgotten. During the same interval, new technologies have emerged. In order to give some perspective to the reader, and hopefully help to make better choices, I’ll review the MySQL HA landscape as it is in 2017. This review will be in three parts. The first part (this post) will cover the technologies that have been around for a long time: the elders. The second part will focus on the technologies that are very popular today: the adults. Finally, the last part will try to extrapolate which technologies could become popular in the upcoming years: the …

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Observations on the hashicorp/raft library, and notes on RDBMS

The hashicorp/raft library is a Go library to provide consensus via Raft protocol implementation. It is the underlying library behind Hashicorp's Consul.

I've had the opportunity to work with this library a couple projects, namely freno and orchestrator. Here are a few observations on working with this library:

  • TL;DR on Raft: a group communication protocol; multiple nodes communicate, elect a leader. A leader leads a consensus (any subgroup of more than half the nodes of the original group, or hopefully all of them). Nodes may leave and rejoin, and will remain consistent with consensus.
  • The hashicorp/raft library is an implementation of …
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