Is it unnecessary to format query if args is empty sequence or empty dict

[Vimiix Yao]

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Please complete the following information:

• OS: Rocky Linux 8.8 (Green Obsidian)
• Psycopg version: '2.9.6 (dt dec pq3 ext lo64)'
• Python version: 3.9.17
• PostgreSQL version: 15
• pip version: 23.0.1

Describe the bug

I am testing the use of the cur.execute api. When my SQL contains the % symbol, I expect the api can determine whether it is formatted by the number of arguments, not just compare with Py_None

>>> sql = "select '1%%s'"
>>> cursor.execute(sql)
>>> cursor.fetchone()
('1%%s',)
>>> cursor.execute(sql, [])
>>> cursor.fetchone()
('1%s',) # expect ('1%%s',)

By locating code, I find that it only checked if the argument is None, and does not handle empty cases.
Can we consider compatibility with empty list or empty dict here?

[Daniele Varrazzo]

No, it would be a massive non-backward incompatibility.

[Vimiix Yao]

OK, thanks for your reply.