Change the MySQL Temporary Files Directory
By default, MySQL’s temporary files are stored in the tmp\ subdirectory of your XAMPP installation directory (usually, C:\xampp). In case you wish to change the location of this directory, follow these steps:
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Edit the my.ini file in the mysql\bin\ subdirectory of your XAMPP installation directory. Within this file, find the tmpdir variable in the [mysqld] section and change it to reflect your new desired location. For example: tmpdir = "D:/temp" 
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Save your changes to the file. 
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Restart the MySQL server using the XAMPP control panel. 
MySQL’s temporary files should now get created in the new location.