Difference between PositiveInteger and PositiveSmallInteger Field in Django

Question

There is no difference between PositiveInteger and PositiveSmallInteger field in the Django source code. But, Django documentation says,

PositiveInteger starts from 0 to 2147483647 and PositiveSmallInteger starts from  0 to 32767.

Please clarify me what is the difference between these two types.

Thanks in advance.

Answer 1

This is one of those things that is the way it is because it got that way.

Django supports SmallIntegerField because Django grew up on PostgreSQL, and PostgreSQL supports smallint. The PosgreSQL docs say

The smallint type is generally only used if disk space is at a premium.

Also there's a difference in the code if you check the backends of Django. There you see it uses the SMALLINT feature on some databases, for example sqlite.

...
class FlexibleFieldLookupDict:
    # Maps SQL types to Django Field types. Some of the SQL types have multiple
    # entries here because SQLite allows for anything and doesn't normalize the
    # field type; it uses whatever was given.
    base_data_types_reverse = {
        'bool': 'BooleanField',
        'boolean': 'BooleanField',
        'smallint': 'SmallIntegerField',
        'smallint unsigned': 'PositiveSmallIntegerField',
        'smallinteger': 'SmallIntegerField',
        'int': 'IntegerField',
        'integer': 'IntegerField',
        'bigint': 'BigIntegerField',
        'integer unsigned': 'PositiveIntegerField',
        'decimal': 'DecimalField',
        'real': 'FloatField',
...