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From "alessandro.benedetti" <abenede...@apache.org>
Subject Re: Can't get spelling suggestions to work properly
Date Thu, 12 Jan 2017 10:13:34 GMT
Hi Jimi,
taking a look to the *maxQueryFrequency*  param :

Your understanding is correct.

1) we don't provide misspelled suggestions if we set the param to 1, and we
have a minimum of 1 doc freq for the term .

2) we don't provide misspelled suggestions if the doc frequency of the term
is greater than the max limit set.

Let us explore the code :

if (suggestMode==SuggestMode.SUGGEST_WHEN_NOT_IN_INDEX && docfreq > 0) {
      return new SuggestWord[0];
    }
/// If we are working in "Not in Index Mode" , with a document frequency >0
we get no misspelled corrections.
/
    
    int maxDoc = ir.maxDoc();
    
    if (maxQueryFrequency >= 1f && docfreq > maxQueryFrequency) {
      return new SuggestWord[0];
    } else if (docfreq > (int) Math.ceil(maxQueryFrequency * (float)maxDoc))
{
      return new SuggestWord[0];
    }
// then the MaxQueryFrequency as you correctly stated enters the game
    
...

Let's explore how you can end up in the first scenario :

if (maxResultsForSuggest == null || hits <= maxResultsForSuggest) {
          SuggestMode suggestMode = SuggestMode.SUGGEST_WHEN_NOT_IN_INDEX;
          if (onlyMorePopular) {
            suggestMode = SuggestMode.SUGGEST_MORE_POPULAR;
          } else if (alternativeTermCount > 0) {
            suggestMode = SuggestMode.SUGGEST_ALWAYS;
          }

You did not set maxResultsForSuggest ( and not onlyMorePopular or
alternative term count) so you ended up in :
SuggestMode suggestMode = SuggestMode.SUGGEST_WHEN_NOT_IN_INDEX;

>From Solr javaDoc :

If left unspecified, the default behavior will prevail.  That is,
"correctlySpelled" will be false and suggestions
   * will be returned only if one or more of the query terms are absent from
the dictionary and/or index.  If set to zero,
   * the "correctlySpelled" flag will be false only if the response returns
zero hits.  If set to a value greater than zero, 
   * suggestions will be returned even if hits are returned (up to the
specified number).  This number also will serve as
   * the threshold in determining the value of "correctlySpelled". 
Specifying a value greater than zero is useful 
   * for creating "did-you-mean" suggestions for queries that return a low
number of hits.
   * </p>
   */
  public static final String SPELLCHECK_MAX_RESULTS_FOR_SUGGEST =
SPELLCHECK_PREFIX + "maxResultsForSuggest";

You probably want to bypass the other parameters and just set the proper
maxResultsForSuggest param for your spellchecker
Cheers



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