I wrote:
>> but I notice that some normalization seems to be getting done by
>> tsqueryin:
>> regression=# select $$( 'sanct' & 'peter' ) <-> ( 'sanct' & 'peter' )$$::tsquery;
>> tsquery
>> ---------------------------------------------------------------------------------------
>> 'sanct' <-> 'sanct' & 'peter' <-> 'sanct' & 'sanct' <-> 'peter' & 'peter' <-> 'peter'
>> (1 row)
> BTW, it seems like that normalization is wrong. The transformed query
> should (and does) match the string "sanct sanct peter sanct sanct peter
> peter peter", since each of the <-> pairs has a match somewhere in there.
> But I would expect the original query to be specifying that a match occurs
> at exactly one place, which of course is unsatisfiable since 'sanct' and
> 'peter' can't match the same word.
After further thought, it seems like a correct transformation would be
to replace & underneath a PHRASE operator with <0>, ie
('a' & 'b') <N> ('c' & 'd')
becomes
('a' <0> 'b') <N> ('c' <0> 'd')
This would have the same effect of getting rid of non-PHRASE operators
underneath a PHRASE, and it would produce what seems to me much less
surprising results, ie you get a match only when both sides of the &
can match at the same place. Comments?
regards, tom lane