From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Alastair McKinley <a(dot)mckinley(at)analyticsengines(dot)com> |
Cc: | "pgsql-general(at)lists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org>, teodor(at)sigaev(dot)ru |
Subject: | Re: websearch_to_tsquery() and apostrophe inside double quotes |
Date: | 2019-10-10 13:35:06 |
Message-ID: | 21225.1570714506@sss.pgh.pa.us |
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Lists: | pgsql-general |
Alastair McKinley <a(dot)mckinley(at)analyticsengines(dot)com> writes:
> I am a little confused about what us being generated by websearch_to_tsquery() in the case of an apostrophe inside double quotes.
> ...
> select websearch_to_tsquery('"peter o''toole"');
> websearch_to_tsquery
> ------------------------------
> 'peter' <-> ( 'o' & 'tool' )
> (1 row)
> I am not quite sure what text this will actually match?
I believe it's impossible for that to match anything :-(.
It would require 'o' and 'tool' to match the same lexeme
(one immediately after a 'peter') which of course is impossible.
The underlying tsvector type seems to treat the apostrophe the
same as whitespace; it separates 'o' and 'toole' into
distinct words:
# select to_tsvector('peter o''toole');
to_tsvector
--------------------------
'o':2 'peter':1 'tool':3
(1 row)
So it seems to me that this is a bug: websearch_to_tsquery
should also treat "'" like whitespace. There's certainly
not anything in its documentation that suggests it should
treat "'" specially. If it didn't, you'd get
# select websearch_to_tsquery('"peter o toole"');
websearch_to_tsquery
----------------------------
'peter' <-> 'o' <-> 'tool'
(1 row)
which would match this tsvector.
regards, tom lane
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