Hello Tom,
On 17.12.2016 21:36, Tom Lane wrote:
4. The transformations are wrong anyway. The OR case I showed above is
all right, but as I argued in <24331.1480199...@sss.pgh.pa.us>, the AND
case is not:
regression=# select 'a <-> (b & c)'::tsquery;
tsquery
---------------------------
'a' <-> 'b' & 'a' <-> 'c'
(1 row)
This matches 'a b a c', because 'a <-> b' and 'a <-> c' can each be
matched at different places in that text; but it seems highly unlikely to
me that that's what the writer of such a query wanted. (If she did want
that, she would write it that way to start with.) NOT is not very nice
either:
If I'm not mistaken PostgreSQL 9.6 and master with patch
"fix-phrase-search.patch" return false for the query:
select 'a b a c' @@ 'a <-> (b & c)'::tsquery;
?column?
----------
f
(1 row)
I agree that such query is confusing. Maybe it is better to return true
for such queries?
Otherwise it seems that queries like 'a <-> (b & c)' will always return
false. Then we need maybe some warning message.
--
Artur Zakirov
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company
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