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Mysql on twitter

Twitter has published improvements for MySQL.

The source code of the changes is distributed under a modified BSD license and is located on GitHub

Read more detailed changes under habrakatom.



Additional state variables



The developers added additional state variables, in particular, from the internal components of InnoDB, which made it possible to more effectively control the operation of the systems and better understand their behavior, especially at the moment of load. Among the added variables are:





Optimize memory allocation based on NUMA



Most modern multiprocessor systems use the technology of uneven memory access, or as it is called the NUMA architecture, which allows you to share the total memory of the system between the "nodes" NUMA. When allocating a large amount of memory for the InnoDB buffer pool, there are usually serious problems. For more information on the typical problems encountered in the NUMA systems used by MySQL, see Jeremy Cole's blog. The developers made the following changes in order to optimize the system and troubleshoot problems:



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Server timeout request



The amount of unnecessary work performed by the server has been reduced, which allowed the server to cancel in advance requests that last more than a certain wait time to the nearest millisecond.

Exporting and restoring the buffer pool using prefetching



Exporting and restoring the InnoDB buffer pool was made possible through the use of a safe and lightweight method that allows you to create tools for restarting services with minimal impact.



Optimization for solid-state drives (SSD drives)



MySQL has been optimized for machines using SSDs, including optimizing the process of updating pages and reducing the number of records on a disk in order to increase the lifespan of disks.

News source: engineering.twitter.com/2012/04/mysql-at-twitter.html

Text taken from README file .

Source: https://habr.com/ru/post/141773/



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