[LUCENE-453] Using MultiSearcher and ParallelMultiSearcher can change the sort order.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.9
• Component/s: core/search

Environment

Checked with revision 314961 on 2005-10-12

• Assignee: Yonik Seeley
• Reporter: Luc Vanlerberghe
• Created: 13/Oct/05 02:05
• Updated: 3 days ago 16:14
• Resolved: 10/Nov/05 14:58

Description

When using multiple sort criteria the first criterium that indicates a difference should be used.
When a field does not exist for a given document, special rules apply.
From what I see in the code, it is sorted as 0 for integer and float fields, and null Strings are sorted before others.

This works correctly in both Lucene 1.4.3 and in trunk as long as you use a single IndexSearcher (except perhaps in special cases, see other bug reports like LUCENE-374).

However, in MultiSearcher and ParallelMultiSearcher, the results of the separate IndexSearchers are merged and there an error occurs.
The bug is located in FieldDocSortedHitQueue.

It can even be demonstrated by passing a single indexSearcher to a MultiSearcher.

TestCase and patch follow.