Sam Mason <sam(at)samason(dot)me(dot)uk> writes:
> wow, that's kind of fun isn't it. I only thought you could put a
> constant in there. Maybe I should have had a look in the grammar/tested
> it first!
IIRC, it used to be restricted to a constant, a few revisions back.
In current releases the only restriction that stems from laziness is
not allowing a sub-select. (If anyone were to put forward a serious
use-case, we'd probably go fix that.)
The OP's complaint is that we don't allow a variable of the query's own
level, but AFAICT he's still not grasped the point that that leads to an
indeterminate limit value ...
regards, tom lane