You're not wrong, but unfortunately many teams don't.
Probably my favourite "ya'll don't understand how databases work" was where they "reserved" space for MySQL enums; for example for the "active" column it would be something like:
enum(
'active',
'deleted',
'_futureval1',
'_futureval2',
'_futureval3',
'_futureval4',
'_futureval5',
'_futureval6',
'_futureval7',
'_futureval8',
'_futureval9'
)
Enums don't work like that at all; it's just a mapping of int to a string value for readability, and you don't need to "reserve" space to add future values just like you don't need to for ints. Adding a new enum value is easy and cheap. Removing them is not as it requires a full scan of all rows to verify they're used. Even worse, you couldn't easily rename enum labels (at the time, don't know if you can now), making it all worse than useless.
Since this was all on large tables and the effort to fix it was relatively large, but without adding much business value, we never fixed it. We were basically stuck with it. It sure as hell annoyed me every time I looked at it.
I'm not an DBA either, but spending about 5 seconds on the documentation for "enum" would have prevented this. This really doesn't require a PhD in SQL.
Probably my favourite "ya'll don't understand how databases work" was where they "reserved" space for MySQL enums; for example for the "active" column it would be something like:
Enums don't work like that at all; it's just a mapping of int to a string value for readability, and you don't need to "reserve" space to add future values just like you don't need to for ints. Adding a new enum value is easy and cheap. Removing them is not as it requires a full scan of all rows to verify they're used. Even worse, you couldn't easily rename enum labels (at the time, don't know if you can now), making it all worse than useless.Since this was all on large tables and the effort to fix it was relatively large, but without adding much business value, we never fixed it. We were basically stuck with it. It sure as hell annoyed me every time I looked at it.
I'm not an DBA either, but spending about 5 seconds on the documentation for "enum" would have prevented this. This really doesn't require a PhD in SQL.