Re: Sort support for macaddr8
| От | Melanie Plageman |
|---|---|
| Тема | Re: Sort support for macaddr8 |
| Дата | |
| Msg-id | CAAKRu_ZgC-rNML9q-_5XvNXNwLxP5cpow1zGCjg93UhJh7g=nw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Sort support for macaddr8 (Peter Geoghegan <pg@bowt.ie>) |
| Список | pgsql-hackers |
On Mon, Jun 3, 2019 at 2:39 PM Peter Geoghegan <pg@bowt.ie> wrote:
As you know, it's a bit weird that we're proposing adding sort support
with abbreviated keys for a type that is 8 bytes, since you'd expect
it to also be pass-by-value on most platforms, which largely defeats
the purpose of having abbreviated keys (though sort support could
still make sense, for the same reason it makes sense to have it for
int8). However, macaddr8 isn't actually pass-by-value, and it seems
too late to do anything about that now, so abbreviated keys actually
make sense.
so, if what you say is true and it is either not worth it or
potentially a breaking change to make macaddr8 pass-by-value and
adding abbreviated sort support has the potential to avoid "pointer
chasing" and guarantee equivalent relative performance for macaddr8
and macaddr, then that seems worth it.
With regard to macaddr8_abbrev_convert() and memset(), I attached a patch
with the memset() removed, since it is superfluous here.
macaddr8_cmp_internal() already existed before this patch and I noticed
that it explicitly returns int32 whereas the return type of
macaddr_cmp_internal() is just specified as an int. I was wondering why.
I also noticed that the prototype for macaddr8_cmp_internal() was not
at the top of the file with the other static function prototypes. I
added it there, but I wasn't sure if there was some reason that it was
like that to begin with.
potentially a breaking change to make macaddr8 pass-by-value and
adding abbreviated sort support has the potential to avoid "pointer
chasing" and guarantee equivalent relative performance for macaddr8
and macaddr, then that seems worth it.
With regard to macaddr8_abbrev_convert() and memset(), I attached a patch
with the memset() removed, since it is superfluous here.
macaddr8_cmp_internal() already existed before this patch and I noticed
that it explicitly returns int32 whereas the return type of
macaddr_cmp_internal() is just specified as an int. I was wondering why.
I also noticed that the prototype for macaddr8_cmp_internal() was not
at the top of the file with the other static function prototypes. I
added it there, but I wasn't sure if there was some reason that it was
like that to begin with.
--
Melanie Plageman
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