[LUCENE-9257] FSTLoadMode should not be BlockTree specific as it is used more generally in index package

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 8.6
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Bruno Roustant
• Created: 02/Mar/20 13:17
• Updated: 28/Aug/22 15:59
• Resolved: 06/Mar/20 14:01

Description

FSTLoadMode and its associate attribute key (static String) are currently defined in BlockTreeTermsReader, but they are actually used outside of BlockTree in the general "index" package.
CheckIndex and ReadersAndUpdates are using these enum and attribute key to drive the FST load mode through the SegmentReader which is not specific to a postings format. They have an unnecessary dependency to BlockTreeTermsReader.

We could move FSTLoadMode out of BlockTreeTermsReader, to make it a public enum of the "index" package. That way CheckIndex and ReadersAndUpdates do not import anymore BlockTreeTermsReader.
This would also allow other postings formats to use the same enum (e.g. LUCENE-9254)

Issue Links

• links to: GitHub Pull Request #1305
• links to: GitHub Pull Request #1320
• links to: GitHub Pull Request #1328