The effect of the modification of the cost constant value is similar to the modification of the global variable, which only takes effect on the new connection after the modification, and does not take effect on the connection established before the modification (regardless of whether the FLUSH OPTIMIZER_COSTS statement has been executed). If the modification is found to be incorrect or needs to be reset, you can directly set the response cost constant value Just be NULL. The cost constant value can be dynamically modified during the running of the server (realized by modifying the server_cost and engine_cost tables, after the modification is completed, you need to execute the FLUSH OPTIMIZER_COSTS statement to reload). Any remaining NULL constant values will be converted to built-in default constant values when used. Any non-NULL cost estimate constant value specified in the table takes precedence. When the server starts, the cost model table is read into memory, and the value in memory is used when generating the execution plan. * engine_cost: The constant value of the optimizer cost estimate used for the operation of a specific storage engine.
* server_cost: The constant value of the optimizer cost estimate used in the normal operation of the server. The optimizer has a set of editable default "cost constants" (these values are stored in the server_cost and engine_cost tables under the mysql system database), which can be used to adjust the execution plan decision. Overview of the optimizer cost model In order to generate the execution plan, the optimizer uses a cost-based model to estimate various operating costs. In this issue, we will bring you the fifth part of the series "Optimizer Cost Record Table|A comprehensive understanding of mysql system library", please follow us to start the system learning journey of mysql system library! You can download the free Community Server Edition of MySQL 5.7.5 m15 via the Development Releases tab on the MySQL Downloads page and the MySQL source code is also being made publicly available on GitHub.In the last issue of "Statistical Information Recording Table | A Comprehensive Understanding of the MySQL System Library", we introduced the statistical information record table in the mysql system library in detail. Oracle is providing early access to features under development, including MySQL Group Replication and multisource replication, for community testing and feedback through. It supports active-active replication so you can replicate between clusters in different locations with automated conflict detection and resolution you can also use more cores within each node for better scale out of throughput. This has enhancements to increase scalability, uptime, and agility. More than 1 million NoSQL QPS to InnoDB via Memcached were achieved with MySQL 5.7, which is six times more than with MySQL 5.6.Īlongside the improvements to MySQL, Oracle has announced the first MySQL Cluster 7.4 development milestone release. In benchmark tests using SysBench Read-only Point-Selects, at 1,024 connections, MySQL 5.7 delivered 645,000 queries per second (QPS), two times better than MySQL 5.6. Replication performance improvements mean many transactions can to be applied in parallel while maintaining full consistency and supporting transaction retries. The performance of InnoDB has also been improved for faster online and bulk load operations. The costs estimates the optimizer uses are stored in tables that you can configure. The MySQL Optimizer Cost Model should give better query performance, and will also provide more control over execution plans and costs. The improved performance has been achieved using a new optimizer dynamic cost model, improved InnoDB performance, and replication performance improvements. Oracle also announced a variety of additional MySQL product releases and early access features, along with making MySQL source code available on GitHub. Oracle has made several announcements about MySQL at Oracle World, starting with a new development milestone release that has improvements in both performance and manageability.Īccording to Oracle, in benchmarks the new release achieved 645,000 SQL queries per second and more than 1 million NoSQL queries per second. MySQL 5.7 Hits 1 million NoSQL Queries per Second
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