[LUCENE-4299] No way to find term vectors options at read time

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0, 6.0
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Robert Muir
• Created: 09/Aug/12 20:19
• Updated: 28/Aug/22 13:24
• Resolved: 13/Aug/12 02:16

Description

The problem is simple:

1. term vectors can be configured "per-field-per-document", meaning for the "body" field, document 0 can have them, document 1 maybe doesnt at all, document 2 maybe has offsets (no positions), and so on. To me this is not a useful feature at all, no one has ever mentioned a single use case for this, and it just makes our code more complicated. but it is what it is (for this issue)
2. there is no way to discover these options for a field of a document, you have to do things like 'peek ahead' to see the first position of the first term is -1, or same for offsets (except worse, we used to allow anything in offsets so -1 might be an actual value). This makes the merging code really hairy, and tough on end consumers.

So I propose that instead of returning Terms for Vectors, we return VectorTerms (extends Terms), which just adds hasOffsets() and hasPositions(). e.g. lucene40 already knows this from the bits for the field/doc pair and just returns what it knows.