libpq: empty arrays have rank 0 in binary results? whatever the type's rank?
От | Dominique Devienne |
---|---|
Тема | libpq: empty arrays have rank 0 in binary results? whatever the type's rank? |
Дата | |
Msg-id | CAFCRh-82ACBOdFA3BxevZQn4AZuUTi6Z5-q1T99OE=tM5hA9cw@mail.gmail.com обсуждение исходный текст |
Ответы |
Re: libpq: empty arrays have rank 0 in binary results? whatever the type's rank?
|
Список | pgsql-general |
Hi. Selecting/fetching an empty 1D array using a binary-mode PGresult,
gives me back 12 bytes, and the first 4, the rank, is 0, something I was not expecting.
I was expecting dims_rank = 1, then first_dim = 0
Normal? Next two ints are kinda useless given the 0 rank?
It's easy to fix, to support rank=0 for empty arrays, I just want to confirm.
Thanks, --DD
PS: On a side note; where can I find the sending code for arrays?
I didn't find the usual _send() and _recv() functions (but looking on github online...)
PPS: The relevant part of my code is below, for context:
uint32_t dims_rank = read();
if (dims_rank != 1) {
throw std::runtime_error(fmt::format(
"Unsupported array rank: Got {}; Want 1", dims_rank
));
}
uint32_t has_nulls = read();
uint32_t actual_elem_oid = read();
uint32_t first_dim = read();
uint32_t lower_idx = read();
ensure_oid(Oid{ actual_elem_oid }, expected_elem_oid);
UNUSED(has_nulls);
assert(lower_idx == 1);
if (dims_rank != 1) {
throw std::runtime_error(fmt::format(
"Unsupported array rank: Got {}; Want 1", dims_rank
));
}
uint32_t has_nulls = read();
uint32_t actual_elem_oid = read();
uint32_t first_dim = read();
uint32_t lower_idx = read();
ensure_oid(Oid{ actual_elem_oid }, expected_elem_oid);
UNUSED(has_nulls);
assert(lower_idx == 1);
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