Обсуждение: [sqlsmith] Failed assertion in TS_phrase_execute

Hi,

the query below triggers an assertion in TS_phrase_execute.  Testing was
done on master at dbdfd11.

regards,
Andreas

-- TRAP: FailedAssertion("!(curitem->qoperator.oper == 4)", File: "tsvector_op.c", Line: 1432)

select 'moscow' @@      ts_rewrite('moscow', 'moscow',         ts_rewrite(     tsquery_phrase('moscow','moscow'),
'moscow',    $$ 'sanct' & 'peter'$$));
 

Andreas Seltenreich <seltenreich@gmx.de> writes:
> the query below triggers an assertion in TS_phrase_execute.  Testing was
> done on master at dbdfd11.

> -- TRAP: FailedAssertion("!(curitem->qoperator.oper == 4)", File: "tsvector_op.c", Line: 1432)

> select 'moscow' @@
>        ts_rewrite('moscow', 'moscow',
>           ts_rewrite(
>          tsquery_phrase('moscow','moscow'),
>          'moscow',
>          $$ 'sanct' & 'peter'$$));

Hmm.  If you run the ts_rewrite alone, it prints

regression=# select  ts_rewrite('moscow', 'moscow',         ts_rewrite(    tsquery_phrase('moscow','moscow'),
'moscow',   $$ 'sanct' & 'peter'$$));                  ts_rewrite                     
-------------------------------------------------( 'sanct' & 'peter' ) <-> ( 'sanct' & 'peter' )
(1 row)

and if you put that in explicitly, all's well:

regression=# select 'moscow' @@ $$( 'sanct' & 'peter' ) <-> ( 'sanct' & 'peter' )$$::tsquery;?column?
----------f
(1 row)

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)

so this seems to boil down to ts_rewrite failing to apply required
normalization.  Or maybe the normalization shouldn't be required.
        regards, tom lane

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.
        regards, tom lane

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