Re: @> (contains)
| От | David G. Johnston |
|---|---|
| Тема | Re: @> (contains) |
| Дата | |
| Msg-id | CAKFQuwads-TKniO0=EYYG+AQkyxmCbOCD5jPXjjR5ZBk2dyDYg@mail.gmail.com обсуждение исходный текст |
| Ответ на | @> (contains) (PG Doc comments form <noreply@postgresql.org>) |
| Ответы |
Re: @> (contains)
|
| Список | pgsql-docs |
On Sun, Aug 18, 2019 at 8:53 AM PG Doc comments form <noreply@postgresql.org> wrote:
The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.6/functions-array.html
Description:
Hi.
Noticed strange thin with @>
Query "select '{1,2}'::int[] @> '{1,2,2,2,2,2,2,2}'::int[]" returns true,
but first array contains even less elements then second.
I think it's a bug in "contains" logic, but don't know where to submit it.
Its a valid interpretation of "contains", for this purpose each array is treated like a set (ignoring the cardinality of elements, and overall dimensionality), but it needs to be documented as behaving that way on that page. I don't see that its documented anywhere for that matter. The source code documents that dimensions are ignored but is silent on duplication of elements:
array_contain_compare:
/*-----------------------------------------------------------------------------
* array overlap/containment comparisons
* These use the same methods of comparing array elements as array_eq.
* We consider only the elements of the arrays, ignoring dimensionality.
*----------------------------------------------------------------------------
*/
* array overlap/containment comparisons
* These use the same methods of comparing array elements as array_eq.
* We consider only the elements of the arrays, ignoring dimensionality.
*----------------------------------------------------------------------------
*/
David J.
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