官术网_书友最值得收藏!

Merge

This storage engine is also known as a MRG_MyISAM storage engine. This storage engine merges a MyISAM table and creates it to be referred to a single view. For a merge table, all columns are listed in the same order. These tables are good for data warehousing environments.

The following example shows you how to create merge tables:

mysql> CREATE TABLE user1 (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,name CHAR(20)) ENGINE=MyISAM;
mysql> CREATE TABLE user2 (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,name CHAR(20)) ENGINE=MyISAM;
mysql> INSERT INTO user1 (name) VALUES ('abc'),('xyz');
mysql> INSERT INTO user2 (name) VALUES ('def'),('pqr');
mysql> CREATE TABLE user (id INT NOT NULL AUTO_INCREMENT,name CHAR(20), INDEX(id))ENGINE=MERGE UNION=(user1,user2);

The table is used to manage log-related tables, generally. You can create different months of logs in separate MyISAM tables and merge these tables using the merge storage engine.

MyISAM tables have storage limit for the operating system but a collection of MyISAM (merge) tables do not have storage limits. So using a merge table would allow you to split data into multiple MyISAM tables, which can help in overcoming storage limits.

With the MERGE table, it is difficult to do partitioning hence it is not supported by MERGE tables and we cannot implement partition on MERGE table or any MyISAM table.

主站蜘蛛池模板: 广水市| 德令哈市| 新田县| 余庆县| 翁源县| 东莞市| 探索| 息烽县| 临清市| 方山县| 襄樊市| 阳曲县| 玛曲县| 法库县| 玉树县| 东兰县| 砀山县| 六盘水市| 康平县| 滕州市| 互助| 兴仁县| 永济市| 荆州市| 同仁县| 克什克腾旗| 肥乡县| 保康县| 雅安市| 绵竹市| 澄城县| 大荔县| 雷山县| 工布江达县| 馆陶县| 绍兴县| 马龙县| 秭归县| 吉林市| 额尔古纳市| 定远县|