| From: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
|---|---|
| To: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
| Cc: | Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Amit Langote <amitlangote09(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] path toward faster partition pruning |
| Date: | 2018-04-04 07:06:38 |
| Message-ID: | CAKJS1f9xMOKh2gJZVQb22cfDGFKmWhuCAWqW9W04PeBbizHjkA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 4 April 2018 at 17:42, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> I'm not sure about the following change in your patch:
>
> - if (!result->scan_null)
> - result->scan_null = step_result->scan_null;
> - if (!result->scan_default)
> - result->scan_default = step_result->scan_default;
> + result->scan_null |= step_result->scan_null;
> + result->scan_default |= step_result->scan_default;
>
> Afaik, |= does bitwise OR, which even if it might give the result we want,
> is not a logical operation. I had written the original code using the
> following definition of logical OR.
>
> a OR b = if a then true else b
Ok, no problem. I only changed that to make it more compact.
For the record we do the same in plenty of over places over the code base:
E.g.
parse->hasSubLinks |= subquery->hasSubLinks;
/* If subquery had any RLS conditions, now main query does too */
parse->hasRowSecurity |= subquery->hasRowSecurity;
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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