[LUCENE-1478] Missing possibility to supply custom FieldParser when sorting search results

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4
• Fix Version/s: 2.9
• Component/s: core/search
• Lucene Fields: New, Patch Available
• Assignee: Michael McCandless
• Reporter: Uwe Schindler
• Created: 04/Dec/08 16:49
• Updated: 28/Aug/22 11:55
• Resolved: 08/Dec/08 21:08

Description

When implementing the new TrieRangeQuery for contrib (LUCENE-1470), I was confronted by the problem that the special trie-encoded values (which are longs in a special encoding) cannot be sorted by Searcher.search() and SortField. The problem is: If you use SortField.LONG, you get NumberFormatExceptions. The trie encoded values may be sorted using SortField.String (as the encoding is in such a way, that they are sortable as Strings), but this is very memory ineffective.

ExtendedFieldCache gives the possibility to specify a custom LongParser when retrieving the cached values. But you cannot use this during searching, because there is no possibility to supply this custom LongParser to the SortField.

I propose a change in the sort classes:
Include a pointer to the parser instance to be used in SortField (if not given use the default). My idea is to create a SortField using a new constructor

SortField(String field, int type, Object parser, boolean reverse)

The parser is "object" because all current parsers have no super-interface. The ideal solution would be to have:

SortField(String field, int type, FieldCache.Parser parser, boolean reverse)

and FieldCache.Parser is a super-interface (just empty, more like a marker-interface) of all other parsers (like LongParser...). The sort implementation then must be changed to respect the given parser (if not NULL), else use the default FieldCache.getXXXX without parser.

Issue Links

• is blocked by: LUCENE-1481 Sort and SortField does not have equals() and hashCode()