From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: "tim.connolly@oovvuu.com" <tim.connolly@oovvuu.com>,
        "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #17125: Operator precedence bug in websearch_to_tsquery
 function
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References: <17125-483838072f5f4bac@postgresql.org>
 <CAKFQuwa2v2F9spFbJgnDey9pNtk-R3TOOAJ1VU6fGTD5=Mm4DQ@mail.gmail.com>
Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Wed, 28 Jul 2021 06:40:25 -0700"
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Date: Wed, 28 Jul 2021 10:13:35 -0400
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Tuesday, July 27, 2021, PG Bug reporting form <noreply@postgresql.org>
> wrote:
>> postgres=# select websearch_to_tsquery('english', 'foo bar or baz');
>> websearch_to_tsquery
>> -----------------------
>> 'foo' & 'bar' | 'baz'
>> (1 row)
>> 
>> Expected: 'foo' & ('bar' | 'baz')

> The documentation describes the operator precedence and it isn’t what you
> expect.

It does appear from what I could find on the web that Google does it
the other way.  Whether that's enough reason to change a behavior
that's stood since v11 is hard to say.  We're not trying to be
entirely bug-compatible with Google here ... and even if we were,
who's to say whether they might not change this tomorrow?

Perhaps a more useful way to think about it is whether it's possible
to get the behavior opposite to the default.  AFAICS there isn't any
way to get 'a & (b | c)' out of websearch_to_tsquery.  However, if
we changed the default precedence, then there'd be no way to get the
old behavior, which is not nice at all.  I first thought that maybe
you could write '"a b" or c', but that produces 'a <-> b | c' which
isn't the same.

Anyway, given that most people probably have no idea about this fine
point, I doubt that the benefits of changing it would outweigh the
costs.

			regards, tom lane