[LUCENE-7703] Record the version that was used at index creation time

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 7.0
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Adrien Grand
• Created: 22/Feb/17 11:22
• Updated: 28/Aug/22 15:11
• Resolved: 28/Feb/17 15:01

Description

SegmentInfos already records the version that was used to write a commit and the version that was used to write the oldest segment in the index. In addition to those, I think it could be useful to record the Lucene version that was used to create the index. I think it could help with:

• Debugging: there are things that change based on Lucene versions, for instance we will reject broken offsets in term vectors as of 7.0. Knowing the version that was used to create the index can be very useful to know what assumptions we can make about an index.
• Backward compatibility. The codec API helped simplify backward compatibility of the index files a lot. However for everything that is done on top of the codec API like analysis or the computation of length norm factors, backward compatibility needs to be handled on top of Lucene. Maybe we could simplify this?