Re: remove ATTRIBUTE_FIXED_PART_SIZE

On August 18, 2018 8:37:00 PM GMT+02:00, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> writes:
>> Since the introduction of the CATALOG_VARLEN stuff, the fixed size of
>> pg_attribute is exactly sizeof(FormData_pg_attribute), so the ancient
>> mechanism to track the fixed size manually using
>> ATTRIBUTE_FIXED_PART_SIZE can be removed.
>
>Meh, I'm not sure about this. What about the possibility of trailing
>padding after the last fixed column, as the comment you propose to
>remove is talking about? Sure, we don't have that today, but we
>might again the next time somebody adds a column to pg_attribute.

Where would avoiding that padding be an important thing her? Strictly speaking it's not even safe to access the last members without the padding present - the compiler is free to store with a wider write if that just affects padding. GCC does that in some cases IIRC.

Andres
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.