mysql

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Removal of implicit and explicit sorting for GROUP BY

2019-04-10 KENNETH 0

Removal of implicit and explicit sorting for GROUP BY In MySQL, historically GROUP BY was used to provide sorting as well. If a query specified GROUP BY, the result was sorted as if ORDER BY was present in the query. mysql-5.7> CREATE TABLE t (id INTEGER, cnt INTEGER); Query OK, 0 rows affected (0.03 sec) mysql-5.7> INSERT INTO t VALUES (4,1),(3,2),(1,4),(2,2),(1,1),(1,5),(2,6),(2,1),(1,3),(3,4),(4,5),(3,6); Query OK, 12 rows affected (0.02 sec) Records: 12 Duplicates: 0 Warnings: 0 mysql-5.7> SELECT id, SUM(cnt) FROM t GROUP BY id; +——+———-+ | id | SUM(cnt) | +——+———-+ | 1 | 13 | | 2 | 9 | | 3 | 12 | | 4 | 6 | +——+———-+ 4 rows in set (0.00 sec) MySQL here implicitly sorts the results from GROUP BY (i.e.… Facebook Twitter Google+ LinkedIn Source: Removal of implicit and explicit sorting for GROUP [ more… ]

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Support for Admin Interface in MySQL server

2019-04-01 KENNETH 0

Support for Admin Interface in MySQL server For some time, there have been several requests to the MySQL dev team to add dedicated support for an admin to connect to the MySQL server.  We received a contribution from Facebook, bug#90395 ,  to add this functionality, which we then paired with more requirements, implemented in WL#12138 and delivered in MySQL Server 8.0.14.… Facebook Twitter Google+ LinkedIn Source: Support for Admin Interface in MySQL server

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The –bind-address option now supports multiple addresses

2019-03-26 KENNETH 0

The –bind-address option now supports multiple addresses Before the implementation of WL#11652 in MySQL 8.0.13 , the MySQL server listened to incoming connection requests either on one or all configured network interfaces. However, in case the underlying platform supports several network interfaces it might be useful to allocate more than one network interface for specific use, and therefore allow specifying bind-address for several network interfaces.… Facebook Twitter Google+ LinkedIn Source: The –bind-address option now supports multiple addresses

charset=utf8 VS ‘SET NAMES “utf8″‘ in PHP pdo_mysql

2019-03-26 KENNETH 0

pdo_mysql 기반의 DB커넥션을 찾다보니소개하는 글마다 약간의 차이가 있는 항목이 있음… 바로 charset을 설정하는 부분… 어떤 소개자료에서는$pdo->exec(“set names utf8”)이렇게 설명을 하기도 하고 어떤 소개자료에서는“charset=utf8”이런 형태로… 두 사례의 결과는 동일하지만 “왜 이렇게 해야 하는가?” 하는 의문이 들었음그래서 찾아보니 PHP-5.3.6 이전 버전에서는 charset 옵션이 적용되지 않는 문제가 있었기 때문에$pdo->exec(“set names utf8”)요런식으로 사용해왔음 하지만 이후 버전에서는 해결되어접속 선언 파라미터에$pdo = new PDO(“mysql:host=$host;dbname=$db;charset=utf8”, $user, $pass);즉, “charset=utf8” 옵션을 추가해 주면 된다. 는것… 구버전(php-5.3.6이전)을 사용한다면 전자의 경우를.. 이후 버전을 사용한다면(하긴… 요즘 7.X 까지 나와있으니) 후자의 경우를 사용하면 되겠다.

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MySQL Connection Handling and Scaling

2019-03-20 KENNETH 0

MySQL Connection Handling and Scaling In this post we describe MySQL connections, user threads, and scaling. We hope that an increased understanding of how MySQL works will help application developers and system administrators to make good choices and trade-offs. We describe how connections work in a plain community server and we do not cover related topics such as thread pooling, resource groups, or connection multiplexing in this post.… Facebook Twitter Google+ LinkedIn Source: MySQL Connection Handling and Scaling