Optional generated column for insert/update (default constraint)

Use case: I have a field createdat which is auto generated. I’d expect it to maintain its value regardless of when I update it. Basically looking for a way to enforce a generated column to NOT update its value when an UPDATE command is issued.

Feature description:

Table schema

CREATE TABLE mytable(
    somefield STRING,
    createdat TIMESTAMP GENERATED ALWAYS AS CURRENT_TIMESTAMP(3)
)

INSERT INTO mytable (somefield) VALS ('some string')

'some string', 1517615548000

UPDATE mytable SET somefield = 'another string' WHERE somefield = 'some string'

'another string', 1517615548000

In the above example, it’d be great to persist the original value even if any of the other column values are updated.

[mfussenegger]

I guess to support this use case in a better way we’d have to implement the default constraint?

[mfussenegger]

We added support for DEFAULT in 4.0 (https://github.com/crate/crate/pull/8794)