David Johnston <polobo@xxxxxxxxx> writes: > Zev Benjamin wrote >> It appears that unnest, when called on a multi-dimensional array, >> effectively flattens the array first. For example: ... > Multidimensional arrays do have shortcomings in the current implementation > of which this is one. I'm not sure, though, if there is anything > substantial and centralized in the docs so pertaining. It might be worth explaining that this is a consequence of the fact that Postgres treats all arrays over the same element type as being of the same data type --- that is, 1-D and 2-D arrays are not distinguished by the type system. Thus, when the polymorphic function "unnest(anyarray) returns setof anyelement" is applied to an integer array, it must return a series of integers; not a series of lower-dimensional arrays. There have been some discussions over whether this could be changed without a backwards-compatibility disaster, but nobody sees how. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
