Tag: Performance_Schema

Feed: Planet MySQL; Author: Sheeri K. Cabral; Notes/errata/updates for Chapter 3:See the official book errata at http://tahaghoghi.com/LearningMySQL/errata.php – Chapter 3 includes pages 95 – 106. On p. 96 – 97, there is an example of what you will see with SHOW DATABASES; You will likely also see sys, INFORMATION_SCHEMA and PERFORMANCE_SCHEMA databases. On p. 97, it says “There are some restrictions on what characters and words you can use in your database, table and other names.” These days, it is possible to escape characters and reserved words, but it is still not recommended. On p. 101-102, there are examples of ... Read More

Feed: Planet MySQL; Author: jocelyn fournier; With the release of PrestaShop 1.7.2.2, we have tried to remove a few point of contention which were affecting badly overall PrestaShop performance: Specific price computation Sale page wrong pagination loading too much products on one page Let's check the specific price improvement! According to our internal software, specificPrice computation was particularly slow, AND present across a lot of pages. Basically our software is crawling a website, profile each page it founds, and then generates a global report. SpecificPrice was listed in the top 5 most resource and time consuming operation, overall. Each time a price ... Read More

Feed: Planet MySQL; Author: Mark Callaghan; I used sysbench to compare IO-bound table scan performance for MyRocks, InnoDB and TokuDB. Tests were run on a large server with fast SSD, Intel NUCs with SSD and an Intel NUC with disk. I call this IO-bound because for all tests the table was larger than RAM.tl;drMyRocks can be more than 2X slower than for InnoDB.  InnoDB in 5.7 does better than in 5.6 TokuDB without compression is comparable to InnoDB without compression and does much better than InnoDB when prefetching is enabled. Compression usually has a small impact on scan performance for ... Read More

Feed: Planet MySQL; Author: Mark Callaghan; This post compares MyRocks, InnoDB and TokuDB on the time required to load and index a table for sysbench.tl;drMyRocks, InnoDB and TokuDB have similar load performance although there is a regression for InnoDB from 5.6 to 5.7 to 8.x InnoDB create index is much faster starting in 5.7 ConfigurationI used my sysbench helper scripts with my sysbench branch and configured it to create 1 table with 800M rows. The binlog was enabled but sync on commit was disabled for the binlog and database log. The sysbench client shared the host with mysqld. The host has ... Read More

Feed: Planet MySQL; Author: Valeriy Kravchuk; I have to get back to the topic of checking user variables in gdb to clarify few more details. In his commentShane Bester kindly noted that calling functions defined in MySQL code is not going to work when core dump is studied. So, I ended up with a need to check what does the my_hash_element() function I've used really do, to be ready to repeat that step by step manually. Surely I could skip that and use Python and Shane himself did, but structures of HASH type are widely used in MySQL, so I'd ... Read More

Feed: MariaDB Knowledge Base Article Feed. Author: . MariaDB starting with 5.5PERFORMANCE_SCHEMAはMariaDB5.5で導入されました。 MariaDBのバージョン はじめに パフォーマンススキーマはMariaDB5.5で導入されたサーバーパフォーマンスを監視するための機能です。 これはストレージエンジンとして実装されており、利用可能なストレージエンジンのリストに表示されます。 SHOW ENGINES; +--------------------+---------+----------------------------------+--------------+------+------------+ | Engine | Support | Comment | Transactions | XA | Savepoints | +--------------------+---------+----------------------------------+--------------+------+------------+ | ... | | | | | | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | | ... | | | | | | +--------------------+---------+----------------------------------+--------------+------+------------+ ただし、PERFORMANCE_SCHEMAはデータを格納するための通常のストレージエンジンとは違い、パフォーマンススキーマ機能を実装するための仕組みです。 ストレージエンジンには、performance_schemaというデータベースが含まれています。このデータベースは多数のテーブルで構成されているため、通常のSQL文で問い合わせが可能で、特定のパフォーマンス情報を返します。 USE performance_schema SHOW TABLES; +----------------------------------------------------+ | Tables_in_performance_schema | +----------------------------------------------------+ | accounts | | cond_instances | | events_stages_current | | events_stages_history | | events_stages_history_long | | events_stages_summary_by_account_by_event_name | | events_stages_summary_by_host_by_event_name | | events_stages_summary_by_thread_by_event_name | | ... Read More

Feed: Planet MySQL; Author: Frederic Descamps; Recently I wrote a blog post on how to use ProxySQL with 8.0.2 dmr This blog post was related to the change we implemented in the Group Replication’s monitoring (performance_schema tables) and how sys schema should be changed to modify the view used by ProxySQL according. However, I used my labs machines that I was using for different purposes too and some changes I made hid a problem that avoid ProxySQL to work with the new defaults in MySQL 8.0.2. Thank you Andy for discovering this. In fact the new collation default (utf8mb4_0900_ai_ci) is ... Read More

Feed: Planet MySQL; Author: Marco; Recently Fred published a post (http://lefred.be/content/mysql-group-replication-is-sweet-but-can-be-sour-if-you-misunderstand-it) in which he was stating, I had publish my blog (http://www.tusacentral.net/joomla/index.php/mysql-blogs/191-group-replication-sweet-a-sour.html) which contains few “misunderstanding”. All the people that knows me, also know I have no problem to admit if I do a mistake, at the end doing mistake is a way of learning and be afraid of the ones who don’t do them. But at the same time, I need to have proof of it. As I provide proof of what I wrote with numbers and tests (all available on github). Let us put down the basis of ... Read More

Feed: Percona Database Performance Blog. Author: Marco Tusa. Marco Tusa  | August 1, 2017 |  Posted In: GTID, High-availability, InnoDB, MySQL, Percona XtraDB Cluster, PMM PREVIOUS POST In this blog, we’ll look at group replication and how it deals with flow control (FC) and replication lag.  In the last few months, we had two main actors in the MySQL ecosystem: ProxySQL and Group-Replication (with the evolution to InnoDB Cluster).  While I have extensively covered the first, my last serious work on Group Replication dates back to some lab version years past. Given that Oracle decided to declare it GA, and Percona’s decision ... Read More

Feed: Planet MySQL; Author: Frederic Descamps; MySQL Group Replication: who is the primary master – updated! – lefred's blog: tribulations of a MySQL Evangelist Some time ago I wrote this article explaining how to find which node was the Primary Master in a MySQL Group Replication cluster running in Single-Primary Mode. In the latest release of Group Replication, MySQL 8.0.2 dmr, Jaideep improved the visibility of Group Replication extending the performance_schema tables (see his article). Thanks to these improvements, it’s now very easy to find which host is acting a Primary-Master. This is the query you can use: mysql-sql> SELECT ... Read More