cursor.fetchall() vs list(cursor) in Python

Question

Both methods return a list of the returned items of the query, did I miss something here?
Or they have identical usages indeed?
Any differences performance-wise?

Answer 1

A (MySQLdb/PyMySQL-specific) difference worth noting when using a DictCursor is that list(cursor) will always give you a list, while cursor.fetchall() gives you a list unless the result set is empty, in which case it gives you an empty tuple. This was the case in MySQLdb and remains the case in the newer PyMySQL, where it will not be fixed for backwards-compatibility reasons. While this isn't a violation of Python Database API Specification, it's still surprising and can easily lead to a type error caused by wrongly assuming that the result is a list, rather than just a sequence.

Given the above, I suggest always favouring list(cursor) over cursor.fetchall(), to avoid ever getting caught out by a mysterious type error in the edge case where your result set is empty.