[LUCENE-2773] Don't create compound file for large segments by default

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.9.4, 3.0.3, 3.1, 4.0-ALPHA
• Component/s: core/index
• Lucene Fields: New
• Assignee: Michael McCandless
• Reporter: Michael McCandless
• Created: 20/Nov/10 15:52
• Updated: 28/Aug/22 12:36
• Resolved: 24/Nov/10 19:53

Description

Spinoff from LUCENE-2762.

CFS is useful for keeping the open file count down. But, it costs
some added time during indexing to build, and also ties up temporary
disk space, causing eg a large spike on the final merge of an
optimize.

Since MergePolicy dictates which segments should be CFS, we can
change it to only build CFS for "smallish" merges.

I think we should also set a maxMergeMB by default so that very large
merges aren't done.