Symptom Description
The user failed to obtain the slow_query_log_file data by running the following command:
select @@slow_query_log_file;
Error message:
ERROR 1193 (HY000): Unknown system variable 'slow_query_log_file'
Version: 5.7
Possible Causes
Since slow_query_log_file is marked with TENCENT_VAR in MySQL 5.7, the result cannot be obtained directly by running the SELECT command.
Solution
If the error prompt in the above scenario occurs when you attempt to obtain the slow_query_log_file data, run the following command to obtain the corresponding data:
show global variables like '%slow_query_log_file%';