Re: Minor difference in behavior between +/-
| От | David G. Johnston |
|---|---|
| Тема | Re: Minor difference in behavior between +/- |
| Дата | |
| Msg-id | CAKFQuwZpDPkgwX8J46H23hYzN9ezdT5W3cQZA9z5rJgFVOSPjA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Minor difference in behavior between +/- (Ryan Murphy <ryanmurf@gmail.com>) |
| Ответы |
Re: Minor difference in behavior between +/-
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| Список | pgsql-bugs |
On Tuesday, January 24, 2023, Ryan Murphy <ryanmurf@gmail.com> wrote:
SELECT NULL - date '2023-01-05';-> result is null
SELECT NULL + date '2023-01-05';-> result is [42725] ERROR: operator is not unique: unknown + date Hint: Could not choose a best candidate operator. You might need to add explicit type casts. Position: 13
There is no bug here.
I would expect both of those to be null.
I get why you expect that but we expend little to no effort to handle null in a type agnostic way. Type inference has to happen first and regardless of whether the literal is null. Type inference failed in the + case but not the - case. That is just happenstance of what operators happen to exist in the system.
David J.
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