On 23.02.26 09:41, David Rowley wrote:
> On Mon, 23 Feb 2026 at 21:21, Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>> I read in the SQL standard that SELECT * in EXISTS is not supposed to be
>> expanded to all columns, but only to an arbitrary literal. This
>> corresponds to the recommendation in the PostgreSQL documentation to
>> write EXISTS (SELECT 1 ...) instead. But not even our own tests and
>> example code use that latter convention consistently, so I think many
>> users don't know it or observe it either. So implementing that little
>> optimization for SELECT * seems reasonable.
>
>> Thoughts?
>
> Don't we already do this in simplify_EXISTS_query()?
It appears so, but then I think we should update the documentation along
the lines I showed, because I found it misleading about this. New
docs-only patch attached.