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Posted to dev@lucene.apache.org by "Hoss Man (JIRA)" <ji...@apache.org> on 2011/08/22 19:27:29 UTC
[jira] [Commented] (LUCENE-3390) Incorrect sort by Numeric values
for documents missing the sorting field
[ https://issues.apache.org/jira/browse/LUCENE-3390?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13088832#comment-13088832 ]
Hoss Man commented on LUCENE-3390:
----------------------------------
This is a fairly well known behavior of the FieldCache in Lucene (and all sorting uses FieldCache) ... i'm guessing it's probably not documented very well however.
There are a bunch of open issues that relate to trying to rectify this problem - but the one known work arround at this point is to *not* use NumericField, and use StrIndex based FieldCache (which does understand docs w/o values). This is the approach used in Solr for the "Sortable*Field" numerics.
> Incorrect sort by Numeric values for documents missing the sorting field
> ------------------------------------------------------------------------
>
> Key: LUCENE-3390
> URL: https://issues.apache.org/jira/browse/LUCENE-3390
> Project: Lucene - Java
> Issue Type: Bug
> Components: core/search
> Affects Versions: 3.3
> Reporter: Gilad Barkai
> Priority: Minor
> Labels: double, float, int, long, numeric, sort
> Attachments: SortByDouble.java
>
>
> While sorting results over a numeric field, documents which do not contain a value for the sorting field seem to get 0 (ZERO) value in the sort. (Tested against Double, Float, Int & Long numeric fields ascending and descending order).
> This behavior is unexpected, as zero is "comparable" to the rest of the values. A better solution would either be allowing the user to define such a "non-value" default, or always bring those document results as the last ones.
> Example scenario:
> Adding 3 documents, 1st with value 3.5d, 2nd with -10d, and 3rd without any value.
> Searching with MatchAllDocsQuery, with sort over that field in descending order yields the docid results of 0, 2, 1.
> Asking for the top 2 documents brings the document without any value as the 2nd result - which seems as a bug?
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