Re: [BUGS] BUG #14626: array_agg( anyarray ) unexpected error withmulti-valued single-dimension array
| От | David G. Johnston |
|---|---|
| Тема | Re: [BUGS] BUG #14626: array_agg( anyarray ) unexpected error withmulti-valued single-dimension array |
| Дата | |
| Msg-id | CAKFQuwb+Zm4V4GaroT8A2DJ96K91RDe3uP+5URQwjC3ZaT4hZQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [BUGS] BUG #14626: array_agg( anyarray ) unexpected error withmulti-valued single-dimension array ("David G. Johnston" <david.g.johnston@gmail.com>) |
| Список | pgsql-bugs |
david.g.johnston@gmail.com writes:
> This doesn't, and should since the number of elements in the non-empty array
> shouldn't change the dimensionality logic.
> SELECT array_agg(CASE WHEN a = ARRAY[]::text[] THEN ARRAY['N/A']::text[]
> ELSE a END)
> FROM ( VALUES (1, ARRAY[]::text[]), (1, ARRAY['1','2']::text[]) ) vals (v,
> a)
Why do you think that should work? You're asking array_agg to accumulate
a 1-D length-1 array and then a 1-D length-2 array. There's no way to
make a rectangular 2-D array out of that, except perhaps by inventing
entries which isn't in array_agg's charter.All this and all I really want is a friggin' "array_append / array_concat" aggregate function that accepts either scalars or matching "primary dimension" arrays - and treats empty arrays as no-ops.
In the end I realized that serializing the arrays to text would work just fine. The extra I/O for converting from and to an actual array type is immaterial in my situation. It still doesn't remove my actual desire for an aggregate array_concat type function, and the for a rectangular array is a bit annoying (i.e., allow non-rectangular and just report an out-of-bounds error on attempts to explicitly access non-existent elements) but that's easy enough to toss in with the other peculiarities in this area.
SELECT unnest(array_agg)::text[]
FROM (
SELECT array_agg(a)
FROM ( VALUES (1, ARRAY[]::text[]::text), (1, ARRAY['1','2']::text[]::text) ) vals (v, a)
) txt_arrays;
David J.
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