What is better in MYSQL count(*) or count(1)?

Question

Related (SQL Server): Count(*) vs Count(1)

Could you please tell me what is better in performance (MySQL)? Count(*) or count(1)?

Answer 1

This is a MySQL answer.

They perform exactly the same - unless you are using MyISAM, then a special case for COUNT(*) exists. I always use COUNT(*) anyway.

https://dev.mysql.com/doc/refman/5.6/en/aggregate-functions.html#function_count

For MyISAM tables, COUNT(*) is optimized to return very quickly if the SELECT retrieves from one table, no other columns are retrieved, and there is no WHERE clause. For example:

mysql> SELECT COUNT(*) FROM student; 

This optimization only applies to MyISAM tables, because an exact row count is stored for this storage engine and can be accessed very quickly. COUNT(1) is only subject to the same optimization if the first column is defined as NOT NULL.

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###EDIT Some of you may have missed the dark attempt at humour. I prefer to keep this as a non-duplicate question for any such day when MySQL will do something different to SQL Server. So I threw a vote to reopen the question (with a clearly wrong answer).

The above MyISAM optimization applies equally to

COUNT(*) COUNT(1) COUNT(pk-column) COUNT(any-non-nullable-column) 

So the real answer is that they are always the same.