[Xapian-discuss] php and get_termpos (stemming problem?)

[Olly Betts]

On Wed, Sep 12, 2007 at 12:01:23PM +0200, Wojewsky, Sascha, Heinze wrote:
>   if (!$pos->equals($database->positionlist_end($i->get_docid(),
> $terms->get_term()))) {
[...]
> But the if condition was always false.
> 
> The term (searchstring) from "$terms->get_term()" starts with the
> stemming-"Z". 

See:

http://www.xapian.org/docs/termgenerator.html#stemming

In particular:

    Now we index all terms lowercased with positional information, and also
    stemmed with a 'Z' prefix (unless they start with a digit), but without
    positional information.

So your "if" condition is always false because there's no positional
information stored for 'Z'-prefixed terms.  This is done because it
saves a lot of disk space, but we can still provide phrase searching
etc (by using the unstemmed forms).

> If I've called $database->positionlist_end($i->get_docid(),
> 'seachstring') without the leading "Z", I've got a result.

You will, provided that the stemmed form is also an unstemmed word in
the document.

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Cheers,
    Olly