数据库的临时目录空间不够，修改配置文件中的tmpdir，指向一个硬盘空间很大的目录即可。
windows下，找到配置文件my.ini.
[mysqld] tmpdir=D:/work/tool/mysql-5.6.28-winx64/temp
修改完毕重启。
附：查询当前临时目录
SHOW VARIABLES LIKE '%tmp%';
The default storage engine for TEMPORARY tables (created with CREATE TEMPORARY TABLE). To set the storage engine for permanent tables, set the default_storage_engine system variable.
If you disable the default storage engine at server startup, you must set the default engine for both permanent and TEMPORARY tables to a different engine or the server will not start.It was added in MySQL 5.6.3.
控制 CREATE TEMPORARY TABLE 创建的临时表的引擎类型.
This variable is unused. It is deprecated as of MySQL 5.6.7 and will be removed in a future MySQL release.
The name of the directory where the slave creates temporary files for replicating LOAD DATA INFILE statements.
The maximum size of internal in-memory temporary tables. This variable does not apply to user-created MEMORY tables.
The directory used for temporary files and temporary tables. This variable can be set to a list of several paths that are used in round-robin fashion. Paths should be separated by colon characters (:) on Unix and semicolon characters (;) on Windows.