[LUCENE-2513] IndexReader overwrites future commits when you open it on a past commit

• Type: Bug
• 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: 24/Jun/10 14:27
• Updated: 28/Aug/22 12:28
• Resolved: 29/Oct/10 19:53

Description

Hit this on trying to build up a test index for perf testing...

IndexReader (and Writer) accept an IndexCommit on open.

This is quite powerful, because, if you use a deletion policy that keeps multiple commits around, you can open a not-current commit, make some changes, write a new commit, all without altering the "future" commits.

I use this to first build up a big wikipedia index, including one commit w/ multiple segments, then another commit after optimize(), and then I open an writable IR to perform deletions off of both those commits. This gives me a single test index that has all four combinations (single vs multi segment; deletions vs no deletions).

But IndexReader has a bug whereby it overwrites the segments_N file. (IndexWriter works correctly).