Tag: collation

Feed: Planet MySQL; Author: Geir Hoydalsvik; We proudly announce General Availability of MySQL 8.0. Download now! MySQL 8.0 is an extremely exciting new version of the world’s most popular open source database with improvements across the board. Some key enhancements include: SQL Window functions, Common Table Expressions, NOWAIT and SKIP LOCKED, Descending Indexes, Grouping, Regular Expressions, Character Sets, Cost Model, and Histograms. JSON Extended syntax, new functions, improved sorting, and partial updates. With JSON table functions you can use the SQL machinery for JSON data. GIS Geography support. Spatial Reference Systems (SRS), as well as SRS aware spatial datatypes,  spatial ... Read More

Feed: MariaDB Knowledge Base Article Feed. Author: . 语法 CREATE [OR REPLACE] [DEFINER = {user | CURRENT_USER | role | CURRENT_ROLE }] [AGGREGATE] FUNCTION [IF NOT EXISTS] func_name ([func_parameter[,...]]) RETURNS type [characteristic ...] RETURN func_body func_parameter: param_name type type: Any valid MariaDB data type characteristic: LANGUAGE SQL | [NOT] DETERMINISTIC | { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA } | SQL SECURITY { DEFINER | INVOKER } | COMMENT 'string' func_body: Valid SQL procedure statement 描述 可以使用CREATE FUNCTION语句创建一个新的存储函数stored function。要使用CREATE FUNCTION语句，必须要具备CREATE ROUTINE数据库权限。 函数可以定义任意数量的参数，在函数体(func_body)部分会返回一个值。函数体部分可以是任意有效的SQL表达式，例如某些select语句。如果你有合适的权限，你完全可以像调用内置函数一样调用存储函数。关于权限的详细信息，见下文：Security。 此外，你也可以使用CREATE FUNCTION语句的变体格式来安装一个用户自定义函数(UDF)。关于UDF，详细信息见：CREATE FUNCTION (UDF)。 你可以使用一个圆括号包围SELECT作为func_body部分，正如使用子查询一样。但注意，SELECT语句必须返回单个值(标量值，即单行且单列的值)。调用函数时，如果SELECT语句返回了多列，则报1241的错误，如果SELECT语句返回了多行，则报1242的错误。为了保险，可以使用LIMIT子句保证只返回单行数据。 你可以使用BEGIN...END语句块替换这里的RETURN子句，但是在语句块中，必须要包含一个RETURN语句。当调用函数时，执行到RETURN子句时将立即返回其结果，在RETURN子句之后的语句都不会再执行。 默认情况下，函数是关联到默认数据库上的。如果要将函数显式关联到一个指定的数据库，可以在创建时使用全称db_name.func_name。如果创建的存储函数名和内置的函数名同名，则必须使用全称来调用它。 定义存储函数时，参数列表可以为空。如果指定参数名，则参数名不区分大小写。 每个参数都可以声明为任意有效的数据类型，但无法使用COLLATE属性。 聚合函数 RETURNS子句 ... Read More

Feed: SQL Server Blog. Author: SQL Server Team. This post is authored by Alan Yu, Program Manager, SQL Server. Download SSMS 17.6 and review the Release Notes to get started. SSMS 17.6 provides support for almost all feature areas on SQL Server 2008 through the latest SQL Server 2017, which is now generally available. In addition to enhancements and bug fixes, SSMS 17.6 comes with several exciting new features: Added more support for Azure SQL Database Managed Instance. Fixed a key performance issue in SMO where scripting tables on SQL Server 2016 took 30 seconds, but now take less than ... Read More

Feed: Planet PostgreSQL. Key Things to Monitor in PostgreSQL - Analyzing Your Workload In computer systems, monitoring is the process of gathering metrics, analyzing, computing statistics and generating summaries and graphs regarding the performance or the capacity of a system, as well as generating alerts in case of unexpected problems or failures which require immediate attention or action. Therefore, monitoring has two uses: one for historic data analysis and presentation which help us identify medium and long term trends within our system and thus help us plan for upgrades, and a second one for immediate action in case of trouble ... Read More

Feed: Planet PostgreSQL. Key Things to Monitor in PostgreSQL - Analyzing Your Workload In computer systems, monitoring is the process of gathering metrics, analyzing, computing statistics and generating summaries and graphs regarding the performance or the capacity of a system, as well as generating alerts in case of unexpected problems or failures which require immediate attention or action. Therefore, monitoring has two uses: one for historic data analysis and presentation which help us identify medium and long term trends within our system and thus help us plan for upgrades, and a second one for immediate action in case of trouble ... Read More

Feed: Planet MySQL; Author: Frederic Descamps; Prior to MySQL 8.0, MySQL was missing a very well know feature in other RDBMS: optimizer histograms. The Optimizer Team implemented this feature as more and more MySQL DBAs were requesting it. Definition But what are histograms ? For wikipedia, a histogram is an accurate representation of the distribution of numerical data. For RDBMS, a histogram is an approximation of the data distribution within a specific column. So in MySQL, histograms help the optimizer to find the most efficient Query Plan. Example To illustrate how histograms  influence the optimizer, I will use data from ... Read More

Feed: Planet MySQL; Author: MySQL Performance Blog; In this post I’ll look at some of our recent work for benchmark enthusiasts: a TPCC-like workload for Sysbench (version 1.0 or later). Despite being 25 years old, the TPC-C benchmark can still provide an interesting intensive workload for a database in my opinion. It runs multi-statement transactions and is write-heavy. We also decided to use Sysbench 1.0, which allows much more flexible LUA scripting that allows us to implement TPCC-like workload. For a long time, we used the tpcc-mysql (https://github.com/Percona-Lab/tpcc-mysql) tool for performance evaluations of MySQL and Percona Server for MySQL, but we recognize that ... Read More

Feed: What's New. Amazon RDS for PostgreSQL now supports PostgreSQL major version 10. PostgreSQL 10 includes various new features including native table partitioning, support for improved parallelism in query execution, ICU collation support, column group statistics, enhanced postgres_fdw extension, and many more. Additionally, this release includes an upgraded version of the PLV8 extension and will have huge pages enabled by default.  ... Read More

Feed: Planet MySQL; Author: Jaime Crespo; I am happy that the MySQL team is, during the last years, blogging about each major feature that MySQL Server is getting; for example, the series on Recursive Common Table Expressions. Being extremely busy myself, I appreciate taking the time to share details with the advantage of being an insider point of view. However, first party guides and examples can be seen at times as not terrible useful at first- as normally they are done with synthetic, artificial examples and not real-life ones. I want to share with you 2 examples of how 2 ... Read More

Feed: Percona Database Performance Blog. Author: Dmitriy Kostiuk. Percona announces the GA release of Percona Server for MySQL 5.7.21-20 on February 19, 2018. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository. Based on MySQL 5.7.21, including all the bug fixes in it, Percona Server for MySQL 5.7.21-20 is the current GA release in the Percona Server for MySQL 5.7 series. Percona provides completely open-source and free software. New Features: A new string variable version_suffix allows to change suffix for the Percona Server version string returned by the ... Read More