Re: Incorrect comments in partition.c

On 2018/01/23 20:43, Etsuro Fujita wrote:
> Here is a comment for get_qual_for_list in partition.c:
>
> * get_qual_for_list
> *
> * Returns an implicit-AND list of expressions to use as a list partition's
> - * constraint, given the partition key and bound structures.
>
> I don't think the part "given the partition key and bound structures."
> is correct because we pass the *parent relation* and partition bound
> structure to that function. So I think we should change that part as
> such. get_qual_for_range has the same issue, so I think we need this
> change for that function as well.

Yeah. It seems 6f6b99d1335 [1] changed their signatures to support
handling default partitions.

> Another one I noticed in comments in partition.c is:
>
> * get_qual_for_hash
> *
> * Given a list of partition columns, modulus and remainder
> corresponding to a
> * partition, this function returns CHECK constraint expression Node for
> that
> * partition.
>
> I think the part "Given a list of partition columns, modulus and
> remainder corresponding to a partition" is wrong because we pass to that
> function the parent relation and partition bound structure the same way
> as for get_qual_for_list/get_qual_for_range. So what about changing the
> above to something like this, similarly to
> get_qual_for_list/get_qual_for_range:
>
> Returns a CHECK constraint expression to use as a hash partition's
> constraint, given the parent relation and partition bound structure.

Makes sense.

> Also:
>
> * The partition constraint for a hash partition is always a call to the
> * built-in function satisfies_hash_partition(). The first two
> arguments are
> * the modulus and remainder for the partition; the remaining arguments
> are the
> * values to be hashed.
>
> I also think the part "The first two arguments are the modulus and
> remainder for the partition;" is wrong (see satisfies_hash_partition).
> But I don't think we need to correct that here because we have described
> about the arguments in comments for that function. So I'd like to
> propose removing the latter comment entirely from the above.

Here, too. The comment seems to have been obsoleted by f3b0897a121 [2].

Thanks,
Amit

[1] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=6f6b99d1335

[2] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=f3b0897a121