[LUCENE-509] Performance optimization when retrieving a single field from a document

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 1.9, 2.0.0
• Component/s: core/index
• Assignee: Otis Gospodnetic
• Reporter: Steven Tamm
• Created: 03/Mar/06 02:22
• Updated: 28/Aug/22 11:25
• Resolved: 13/Aug/06 06:15

Description

If you just want to retrieve a single field from a Document, the only way to do it is to retrieve all the fields from the Document and then search it. This patch is an optimization that allows you retrieve a specific field from a document without instantiating a lot of field and string objects. This reduces our memory consumption on a per query basis by around around 20% when a lot of documents are returned.

I've added a lot of comments saying you should only call it if you only ever need one field. There's also a unit test.

Issue Links

• is related to: LUCENE-510 IndexOutput.writeString() should write length in bytes