BUG #17542: tsquery returns incorrect results with nested, conjuncted followed-by operators

Consider the following query:

jordan=> select '((a <2> c) & (b <-> c)) <-> d'::tsquery @@ 'a:1 b:2 c:3
d:4';
?column?
----------
f
(1 row)

I think this should return "true", because both of the expressions on the
left-hand-side of the outer <-> operator of the tsquery do in fact precede
the "d" term in the tsvector.

Here is output that shows this:

jordan=> select '((a <2> c)) <-> d'::tsquery @@ 'a:1 b:2 c:3 d:4';
?column?
----------
t
(1 row)

jordan=> select '((b <-> c)) <-> d'::tsquery @@ 'a:1 b:2 c:3 d:4';
?column?
----------
t
(1 row)

I think things go wrong in the query executor because the two LHS clauses
have different widths.

Do you agree that this is incorrect output?

I guess this result is derived from the agreement that logical operation
inside the phrase operator is treated as
"both operands a and b are in the _same_ position just before c".

select '(a & b) <-> c'::tsquery @@ 'a:1 b:1 c:2';
?column?
----------
t
(1 row)

Though it's not clear what it means if there is another phrase operator
inside logical. Result positions of (a <2> c) and (b <-> c) are different,
I guess. It's not clear to me how should this behave in the case of a chain
of nested phrase-logical-phrase operations.

--
Best regards,
Pavel Borisov

On Mon, Jul 11, 2022, 08:35 Pavel Borisov <pashkin.elfe@gmail.com> wrote:

I guess this result is derived from the agreement that logical operation
inside the phrase operator is treated as
"both operands a and b are in the _same_ position just before c".

select '(a & b) <-> c'::tsquery @@ 'a:1 b:1 c:2';
?column?
----------
t
(1 row)

Though it's not clear what it means if there is another phrase operator
inside logical. Result positions of (a <2> c) and (b <-> c) are different,
I guess. It's not clear to me how should this behave in the case of a chain
of nested phrase-logical-phrase operations.

I would expect that the "position" of a match should depend on whether it's
the LHS or RHS of the phrase operator. If it's the LHS, I'd expect the
"position" to be the "end" of the match. If it's the RHS, I'd expect the
"position" to be the "beginning" of the match.

Maybe that's the wrong intuition and it's always the beginning of the match?

Jordan