> Down to practicalities, we need Lucene 4.8 as our DocValues are Disk > based and that support was removed in 4.9.
I assume you’re referring to the “Disk” DV format/Codec? The standard format has the data on disk too, it’s just that there’s some “small” (relative to the disk data) lookup references in heap/memory whereas the codec you’re using doesn’t. Are you sure the standard codec isn’t sufficient? If your use-case shows that there’s a need for the disk codec, I think it could be brought back, perhaps into the codecs module. You could copy the code too to use newer Lucene versions… although I recall some push vs pull API changes so I don’t know what it would take to bring it up to date. I’m curious what Rob Muir says about this. ~ David
