PossitionIndex (was: Re: [Zope-dev] ZCatalog phrase indexingrevisited)

[Dieter Maurer]

Rik Hoekstra writes:
 > This raises the question how dependent the splitter on the paticularities of the
 > document source - I do not really see how different splitters could be useful
 > for one single document. This is perhaps less obvious than it appears, as you
 > may want to use different splitters for documents in different languages. Taken
 > as a whole I would say choosing a splitter would be a decision that had to be
 > taken at indexing time anyway. But perhaps it's just my imagination that is
 > lacking. 
There are lots of things you may want to change based on
experience with your index:

  *  change the set of token boundary characters
     they define, where words are broken out.

  *  change the set of removed characters
     they are removed from the words, usually for
     normalization.

     In German, e.g., you can write both "Auto-Lackierer"
     and "Autolackierer". You want to normalize
     these different spellings.

  *  change the set of "composing" characters

     German is very rich in composite terms.
     You may want to index under each component term.
     For this, you need the rules on how the composition
     is build.
     For text, it is usually '-'. But if you have
     computer sources, '_' or ':' may be relevant, too.

Of couse, the search must follow the same splitting rules
than the indexing did. Changing the rules (the splitter
or its configuration) after indexing will make the index
inconsistent.


Dieter