Re: [HACKERS] pow support for pgbench
| От | Raúl Marín Rodríguez |
|---|---|
| Тема | Re: [HACKERS] pow support for pgbench |
| Дата | |
| Msg-id | CAM6_UM7J4Jo+6OFdQg4KOCzHa8+DP3r-PAajkY-UX4zehsr+Dw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [HACKERS] pow support for pgbench (Fabien COELHO <coelho@cri.ensmp.fr>) |
| Ответы |
Re: [HACKERS] pow support for pgbench
Re: [HACKERS] pow support for pgbench |
| Список | pgsql-hackers |
Hi Fabien,
Thanks for the review.
If a double is always returned, I'm wondering whether keeping the ipow version makes much sense: In case of double loss of precision, the precision is lost, too bad, and casting back to int won't bring it back.
I've kept it because knowing that both are ints enables not making a lot of checks (done in math.h pow) so it's way faster. In my system it's 2-3ns vs ~40ns. I'm willing to settle for using just pow() if that makes it clearer.
In the doc, I'm not sure that "Numeric" brings anything. "Exponentiation" would be enough.
Done.
Also, in pg I just noticed that POW is a shorthand for POWER. Maybe both should be supported? Or not.
I've never used power instead of pow, but I've added for compatibility shake.
Attached the updated patch.
On Thu, Dec 21, 2017 at 10:48 PM, Fabien COELHO <coelho@cri.ensmp.fr> wrote:
Hello Raúl,v7 needs a rebase.
Also, you might try to produce a version which is compatible with Robert's
constraints.
My 0.02€ on this new version: Applies cleanly, compiles and works.
I cannot say that I like it more than the previous version.
If a double is always returned, I'm wondering whether keeping the ipow version makes much sense: In case of double loss of precision, the precision is lost, too bad, and casting back to int won't bring it back.
In the doc, I'm not sure that "Numeric" brings anything. "Exponentiation" would be enough.
Also, in pg I just noticed that POW is a shorthand for POWER. Maybe both should be supported? Or not.
--
Fabien.
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