Re: About get_relation_constraints and include_notnull

On 2016/01/14 23:36, Tom Lane wrote:
> Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> writes:
>> Why does the argument include_notnull argument exist if
>> get_relation_constraints() is being called from only one place? Perhaps we
>> could remove it and add the IS NOT NULL test expression unconditionally if
>> there are any NOT NULL columns.
> 
> Well, you could argue why have a routine at all instead of inlining it
> into the one caller.  IIRC the thought was that other likely uses of
> constraint-fetching might want to see only the actual check constraints.
> Is there some positive benefit from removing the argument?

The function is local to plancat.c and hasn't seen any callers beside
relation_excluded_by_constraints() for a long time (as can be told from
the git history). It's just that initially I thought it's being used
elsewhere which upon inspecting I didn't find any. Not really sure I can
make the analogy but ExecConstraints() performs both NOT NULL and CHECK
constraint checks without any argument.

Though, we could just leave it alone. Sorry for the noise.

Thanks,
Amit