Ferret/lucene syntax

Ruby Apps Ferret
1

I jut noticed this example in the lucene documentation*:

title:(+return +“pink panther”)

I have been using this syntax:

+title:(return AND “pink panther”)

Seemingly with success. Are both acceptable? I couldn’t find any
documentation on “the plus sign” itself.

Thanks for any pointers.

John

*http://lucene.apache.org/java/docs/queryparsersyntax.html#Boolean%
20operators

2

On Thu, Mar 29, 2007 at 06:42:16PM -0400, John B. wrote:

I jut noticed this example in the lucene documentation*:

title:(+return +“pink panther”)

I have been using this syntax:

+title:(return AND “pink panther”)

Seemingly with success. Are both acceptable? I couldn’t find any
documentation on “the plus sign” itself.

the plus sign marks a required clause in a query. A document can only be
a hit if it matches that clause. The opposite of this is the minus sign,
documents that match such a clause can’t be a hit. Internally, Ferret
doesn’t handle AND and such, they get translated by the query parser,
i.e. ‘a AND b’ → ‘+a +b’

Clauses without + or - are optional ‘nice to have’ clauses, they will
raise a document’s score if they match, but the doc won’t be excluded
from the hits if they don’t. So ‘a OR b’ gets transformed into ‘a b’.

Jens

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3

On Mar 30, 2007, at 3:32 AM, Jens K. wrote:

from the hits if they don’t. So ‘a OR b’ gets transformed into ‘a b’.
Thanks for that, I actually was completely unaware of the case
without + or -. Very nice.

However, my question was actually more simple: are the semantics of
these two bit of a query the same?

title:(+return +“pink panther”)

+title:(return AND “pink panther”)

Thanks,
John

4

On Mar 31, 2007, at 1:18 AM, John Joseph B. wrote:

Clauses without + or - are optional ‘nice to have’ clauses, they will

title:(+return +“pink panther”)

+title:(return AND “pink panther”)

I replied to this the other day, but I think my sending address was
incorrect and it didn’t go through - sorry 'bout that. My reply was
this:

Yup, both are acceptable. An “AND” actually affects both sides and
forces them to be required, as if you had used + in front. + is
documented in the document you referenced, just below AND.

If you are combining the queries above with other clauses they may
not be equivalent due to the +title, but if these are the full
queries they are equivalent (at least in Java Lucene).

Erik