Would someone care to defend this code?
int total = 2 * JB_ROOT_COUNT(jb);
...
if (total == 0) { *nentries = 0; PG_RETURN_POINTER(NULL); }
...
while ((r = JsonbIteratorNext(&it, &v, false)) != WJB_DONE) { if (i >= total) { total *= 2;
entries = (Datum *) repalloc(entries, sizeof(Datum) * total); }
The early-exit code path supposes that JB_ROOT_COUNT is absolutely
reliable as an indicator that there's nothing in the jsonb value.
On the other hand, the realloc logic inside the iteration loop implies
that JB_ROOT_COUNT is just an untrustworthy estimate. Which theory is
correct? And why is there not a comment to be seen anywhere? If the code
is correct then this logic is certainly worthy of a comment or three.
regards, tom lane