On Sun, Aug 18, 2019 at 8:53 AM PG Doc comments form <nore...@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. *---------------------------------------------------------------------------- */ David J.
