Re: [PATCH] Phrase search ported to 9.6

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Oleg Bartunov <obartunov(at)gmail(dot)com>
Cc: Teodor Sigaev <teodor(at)sigaev(dot)ru>, Dmitry Ivanov <d(dot)ivanov(at)postgrespro(dot)ru>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>, Artur Zakirov <a(dot)zakirov(at)postgrespro(dot)ru>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, David Steele <david(at)pgmasters(dot)net>
Subject: Re: [PATCH] Phrase search ported to 9.6
Date: 2016-04-01 10:46:29
Message-ID: 20160401104629.GA195885@alvherre.pgsql
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Oleg Bartunov wrote:
> On Thu, Mar 31, 2016 at 9:14 PM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
> wrote:
> > What led you to choose the ? operator for the FOLLOWED BY semantics?
> > It doesn't seem a terribly natural choice -- most other things seems to
> > use ? as some sort of wildcard. What about something like "...", so you
> > would do
> > SELECT q @@ to_tsquery('fatal ... error');
> > and
> > SELECT q @@ (tsquery 'fatal' ... tsquery 'error');
> >
> >
> originally was $, but then we change it to ?, we don't remember why. During
> warming-up this morning we came to other suggestion
> SELECT q @@ to_tsquery('fatal <> error');
> and
> SELECT q @@ to_tsquery('fatal <2> error');
> How about this ?

Well, I noticed that the docs talk about an operator that can be used in
SQL (outside the tsquery parser), as well as an operator that can be
used inside tsquery. Inside tsquery anything would be usable, but
outside that it would be good to keep in mind the rest of SQL operators;
and <> means "different from", so using it for FOLLOWED BY seems odd to

My suggestion of ... (ellipsis) is because that's already known as
related to text, used for omissions of words, where the surrounding
words form a phrase. It seems much more natural to me.

(I also noticed that you can specify a counter together with the
operator, for "at most N words apart", which is not going to work for
the SQL-level operator no matter what you choose. I suppose that's not
considered a problem)

Álvaro Herrera
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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