mysql enables rapid creation of indexes for millions of data

Test data A local table users has 100 million records. There is no index added to the corresponding field before creating this table, so you need to add an index to the table at this time. However, due to the large amount of data, the index addition may not be successful. After thinking of many ways, I finally succeeded in digging the hole.

Start preparations,

user table structure:

CREATE TABLE `users` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8mb4 DEFAULT NULL,
  `add_time` int(11) DEFAULT NULL,  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=1000001 DEFAULT CHARSET=latin1;

An error occurred when trying to use into outfile to export data in navicat:

select * from users into outfile 'users.txt'; //users.txt文件在mysql的dat

As shown below:

I checked online that it is the permissions set by mysql. You can use

show variables like '%secure% ';Check what is the current value of secure-file-priv?

You can see that the secure-file-priv parameter is used to limit which specification LOAD DATA, SELECT ... OUTFILE, and LOAD_FILE() is passed to directory. When the value of secure_file_priv is null, it means that mysqld is restricted from importing and exporting. When the value of secure_file_priv is /tmp/, it means that the import and export of mysqld can only occur in the /tmp/ directory. When the value of secure_file_priv has no specific value, it means that There are no restrictions on the import | export of mysqld.

The exported data must be the specified path of this value before it can be exported. The default may be NULL (what I am looking at here is null ) means that export is prohibited, so you need to set it

Since I am using the my.ini file under the phpstudy, mysql installation path, set the path:

Note: Add double quotation marks to the path name ""
The error remains the same after restarting...

This parameter is not set in mysql.cnf, which means that this parameter is the default value null

So try to modify [mysqld] in mysql.cnf to add secure_file_priv =

The final result is as follows:

Restart mysql again

You can see users.txt Generated in the test database directory at the same level. . .
Then execute:

truncate  users;

创建索引：

create index name using BTREE on users(name);

索引的方式有：BTREE、RTREE、HASH、FULLTEXT、SPATIAL,这里不再赘述他们的区别，网上有很多关于这块的介绍啦

导入文件到相应表users。

load data infile 'users.txt' into table users;

此方式在write 锁住情况下，或对外服务暂停时使用，线上不可能直接这样玩了。

相关推荐：

MySQL创建索引和删除索引的方法

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