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From Otis Gospodnetic <otis_gospodne...@yahoo.com>
Subject Re: Index empty fields
Date Mon, 31 Jul 2006 17:46:10 GMT
Hi Simon,

You can index an empty field ("" value), but there is no point in doing that, really.
If you index am empty string, you will not be able to find documents that had that field empty.
You will not be able to do a WHERE foo IS NULL type of query, unless you detect an empty field
during indexing, and put a dummy value it in instead of am empty string.

Otis

----- Original Message ----
From: Simon Willnauer <simon.willnauer@googlemail.com>
To: java-user@lucene.apache.org
Sent: Monday, July 31, 2006 1:11:22 PM
Subject: Re: Index empty fields

Hi Otis,

well if i have to such a query I need a "dummy" value. To point that
out a bit more in detail...
A xml document has "n" mandatory elements described by a schema or
dtd. Some of the could have empty values. Would it make any difference
to the index / searching  if I just index an empty string?! Well I
guess not, to index an empty string feels good for me to have all
fields in every document. This tiny little disc space does not matter
I guess.

Is that true so far?!

regards Simon

On 7/31/06, Otis Gospodnetic <otis_gospodnetic@yahoo.com> wrote:
> Hi Simon,
>
> If you want to be able to run a "give me all documents that have an empty field F", then
you'll actually have to stuff a "dummy" value when no real value for field F is present. 
If you have an index schema, perhaps that's a good place to add a 'defaultValue'-type attribute
with that dummy value.  Perhaps Solr already has something like this, I'm not sure.
>
> Otis
>
> ----- Original Message ----
> From: Simon Willnauer <simon.willnauer@googlemail.com>
> To: java-user@lucene.apache.org
> Sent: Monday, July 31, 2006 8:22:57 AM
> Subject: Index empty fields
>
> Hello,
>
> I do have a question about fields with empty content should be added
> to the document / index or not. I do have a index schema, which
> defines all field a document can have. if one of the real documents
> has no content for a certain field. should that field be added to the
> index or not.
> Would it make any difference at all?
>
> regards Simon
>
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