MySQL Error Code: 3 error writing file (Errcode: 28)

Question

I am trying to execute a query to return the number of records (which is around 4 millions).

SELECT COUNT(DISTINCT col) FROM table;

I am getting this error: mysql Error Code: 3 error writing file 'C:\Winows\temp\Myffd3.tmp' (Errcode: 28).

What is the cause of the problem. How to fix it? I tried t search, It might seems a disk space issue ? But I have 21 GB free space in the C. Does count command fro one columns require more than this ?

EDIT: : The temp file name is not permanent. Each time I execute the command, I get different name in the error message.

Answer 1

Check that the mysql process user has write access to C:\Windows\temp. Generally, you don't want to be writing to C:\Windows... you are better off setting the directory to somewhere else.

---

OK. What is the file system used on C drive? Perhaps you have too many files in that directory if you're using FAT16 / FAT32 ?