Hi,

I stumbled over this snippet of a query generated by an update action:

SET “updated_at” = (CASE WHEN $1::timestamp != r0.“last_query_at”::timestamp THEN $2::timestamp ELSE r0.“updated_at”::timestamp END)

The attribute is defined as below, i.e. the column is nullable:

attribute :last_query_at, :utc_datetime_usec do
  public? true
  filterable? true
end

When the record/row has NULL in field/column last_query_at and I pass a date-time value for last_query_at to the update action, the operator != prevents the condition to resolve to TRUE, hence updated_at is not changed although the row is changed to a new value for last_query_at (not shown in the snippet above).

That default behavior caught me by surprise.

From what I found so far, I‘d have to use this in the update action to skip the “only update if changed“ optimization:
change atomic_update(:last_query_at, expr(^arg(:last_query_at)))

Am I missing something to make the update of updated_at work without atomic_update?

I am using ash 3.19.3 and ash-postgres 2.6.32.

Update: Using atomic_update leads to the same snippet being generated.