[LUCENE-8060] Enable top-docs collection optimizations by default

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 8.0
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Adrien Grand
• Created: 22/Nov/17 18:22
• Updated: 28/Aug/22 15:22
• Resolved: 01/Aug/18 08:08

Description

We are getting optimizations when hit counts are not required (sorted indexes, MAXSCORE, short-circuiting of phrase queries) but our users won't benefit from them unless we disable exact hit counts by default or we require them to tell us whether hit counts are required.

I think making hit counts approximate by default is going to be a bit trappy, so I'm rather leaning towards requiring users to tell us explicitly whether they need total hit counts. I can think of two ways to do that: either by passing a boolean to the IndexSearcher constructor or by adding a boolean to all methods that produce TopDocs instances. I like the latter better but I'm open to discussion or other ideas?

Sub-Tasks

• TopDocs.totalHits is not always the accurate hit count: Closed
• Allow top collectors to compute lower bounds of the total hit count: Closed