| From: | Teodor Sigaev <teodor(at)sigaev(dot)ru> |
|---|---|
| To: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
| Cc: | Raúl Marín Rodríguez <rmrodriguez(at)carto(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] pgbench more operators & functions |
| Date: | 2017-12-28 13:42:45 |
| Message-ID: | 992df164-6bb0-6a88-1d03-a97d891d715b@sigaev.ru |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
> Here is a rebase after "pow" addition.
Huh, you are fast.
Investigating your patch I found that all arguments of logical AND/OR and CASE
are always evaluated. Seems, it should not be for pair of reasons:
- computing of unneeded args could be too expensive
- computing of unneeded args could complicate scripting code, look:
\set zy 0
\set yz case when :zy = 0 then -1 else (1 / :zy) end
This example will fail although programmer tried to check forbidden value
case when 1>0 then 1 when 1/0 > 0 then 0 else -1 end -- fails too
SQL doesn't evaluate unneeded arguments:
select case when 1>0 then 33 when 1/0 > 0 then -33 else null end;
case
------
33
--
Teodor Sigaev E-mail: teodor(at)sigaev(dot)ru
WWW: http://www.sigaev.ru/
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Antonio Belloni | 2017-12-28 15:00:30 | Re: Contributing some code |
| Previous Message | Thomas Munro | 2017-12-28 13:21:01 | Re: pgsql: Add parallel-aware hash joins. |