MySQL 5.6 MRR的存储过程完美诠释_MySQL

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MySQL 5.6 MRR的存储过程完美诠释 MySQL 5.6 即将发布， 5.6对优化器方面做了诸多优化。 我这次主要解释MRR（MULTI-RANGE-READ）。 我用存储过程解释了这一过程的改变。大家细心体会去吧。我们针对语句：[sql] select log_time from person where nick_name = 'Lucy';   表结构为：[sql] CREATE TABLE `person` (    `id` int(10) unsigned NOT NULL AUTO_INCREMENT,    `nick_name` varchar(40) NOT NULL,    `log_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,    PRIMARY KEY (`id`),        KEY `idx_nick_name` (`nick_name`)  ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=latin1   首先是MySQL 5.5.[sql] DELIMITER $$  USE `ytt`$$  DROP PROCEDURE IF EXISTS `sp_range_scan5_5`$$  CREATE DEFINER=`admin`@`%` PROCEDURE `sp_range_scan5_5`()  BEGIN        -- Sample sql statement is below.        -- select log_time from person where nick_name = 'Lucy';        DECLARE i INT UNSIGNED DEFAULT 0;        DECLARE cnt INT UNSIGNED DEFAULT 0;        SET @result = '';            SELECT COUNT(1) INTO cnt FROM person WHERE nick_name = 'Lucy';              loop1:WHILE i   bitsCN.com