recsplit don't store MPH when keys are monotonically increasing integers.

[sudeepdino008]

get rid of MPHT for cases when keys are incrementing integers. These can be stored simply as ef.
Discussion

[wmitsuda]

FYI: read the discussion on Discord about baseId + ef, I also had this requirement in my non-merged branch, maybe we can dedup some code in the future when it is merged: https://github.com/erigontech/erigon/blob/wmitsuda/ef-optimization-experiments/erigon-lib/recsplit/eliasfano32/rebased_elias_fano.go

[sudeepdino008]

FYI: read the discussion on Discord about baseId + ef, I also had this requirement in my non-merged branch, maybe we can dedup some code in the future when it is merged: https://github.com/erigontech/erigon/blob/wmitsuda/ef-optimization-experiments/erigon-lib/recsplit/eliasfano32/rebased_elias_fano.go

So it seems like we will already have the no-MPH thingy with your optimizations @wmitsuda?

[wmitsuda]

actually we don't, I think. I did only better encoding in the .ef contents, but I didn't changed other places that use the Elias-fano code like other snapshot files (I saw the code briefly, but it is out of scope for this change + simple encoding doesn't apply in those cases; but maybe the rebased elias fano does because I saw your comment in Discord)