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From Jack Krupansky <>
Subject Re: Which default Boolean operator to set, AND or OR?
Date Wed, 15 Jul 2015 14:21:19 GMT
It is simply precision (AND) vs. recall (OR) - the former tries to limit
the total result count, while the latter tries to focus on relevancy of the
top results even if the total result count is higher.

Recall is good for discovery and browsing, where you sort of know what you
generally want, but not exactly with any great precision.

Recall will include results that almost meet the query terms, but maybe
some are missing.

Precision will guarantee and insist that all query terms are present.

One great example for recall is a plagiarism query - enter all the terms
for a passage and then find documents that most closely approximate the
passage without being necessarily exact matches. IOW, the plagiarizer
changes a word here and there.

-- Jack Krupansky

On Wed, Jul 15, 2015 at 8:16 AM, Steven White <> wrote:

> Hi Everyone,
> Out-of-the box, Solr (Lucene?) is set to use OR as the default Boolean
> operator.  Can someone tell me the advantages / disadvantages of using OR
> or AND as the default?
> I'm leaning toward AND as the default because the more words a user types,
> the narrower the result set should be.
> Thanks
> Steve

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