From mboxrd@z Thu Jan  1 00:00:00 1970
From: rlane@club.cc.cmu.edu (Rich Lane)
Date: Sun, 13 Sep 2009 20:31:23 -0400
Subject: [sup-talk] U (unread) search is off
In-Reply-To: <1252773806-sup-11@masanjin.net>
References: <1252504368-sup-9406@ntdws12.chass.utoronto.ca>
	<1252581713-sup-9701@cannonball> <1252590993-sup-3885@masanjin.net>
	<1252595946-sup-171@zyrg.net> <1252773806-sup-11@masanjin.net>
Message-ID: <1252878152-sup-9190@zyrg.net>

Excerpts from William Morgan's message of Sat Sep 12 12:47:14 -0400 2009:
> Reformatted excerpts from Rich Lane's message of 2009-09-10:
> > I thought it was, but it turns out that unless you explicitly add AND
> > operators Xapian will OR terms over the same field such that
> > "label:foo label:bar" gives you the union instead of the intersection.
> 
> Ok. I only ask because I'm considering how to present the Xapian index
> option in 0.9---the options are to not say anything about it, to force
> everyone to switch to it, or anywhere in between. 

Yeah, we do need the query behavior to be reasonable before advertising
the Xapian index. What's your timeline on 0.9?

> > We could fix this by patching Xapian to make this behavior
> > configurable, or we could come up with an index-agnostic simple query
> > language that doesn't support boolean operators.
> 
> The former sounds easier to me. Especially since it seems like this is
> something Xapian should have...

Agreed that Xapian should have this, and I'll probably implement it. We
still need to support people using older Xapian versions though. Whether
this means a log message telling them to use explicit ANDs in their
query, or automatically transforming simple-enough queries into what we
think they actually want, I don't know. I'll also need to add a
workaround for the earlier Xapian bug before this index gets wider
usage.

As far as which index to make the default, Ferret has the advantage of
being installable as a gem dependency. I think this ease of installation
is important enough to block Xapian for now, unless someone can create a
Xapian gem. There's been interest in this before:
http://article.gmane.org/gmane.comp.search.xapian.devel/1408/