There is actually a Wiki page explaining this pretty well... have you seen it?
Index-time expansion means larger indices and inability to easily change synonyms (e.g. you thought of a new synonym for "fish" and want to add it to the already indexed docs). Otis -- Sematext -- http://sematext.com/ -- Lucene - Solr - Nutch ----- Original Message ---- > From: Geoffrey Young <[EMAIL PROTECTED]> > To: solr-user@lucene.apache.org > Sent: Thursday, May 8, 2008 12:06:27 PM > Subject: Re: token concat filter? > > > > Otis Gospodnetic wrote: > > Geoff, > > > > Whether synonyms are applied at index time or query time is > > controlled via schema.xml - it depends on where you put the synonym > > factory, whether in the index-time or query-time section of a > > fieldType. Synonyms are read once on start, I believe. It might be > > good to have them read at index reader open time, as is done with > > elevate component... > > I'm looking a bit more into this now. > > I don't think you need synonyms applied at both query and index time if > you're using expand - one or the other ought to work properly. in fact, > I suspect I'm the last person to figure this out ;) > > the question is, then, which is the more efficient place to apply them? > > my first inclination is to apply them (and other similar expanding > mechanisms) to just the index so that the expansion happens only once > and is held in (an efficient) index as opposed to manipulating every query. > > the SpellCheckerRequestHandler example on the wiki has the opposite > configuration, expanding synonyms on (only) the query. > > thoughts on which approach is the more efficient one? > > --Geoff
