Once level extension happens (i.e., the interlevel compaction to a
new level), we can just move all tables in the previous level to the
new level without re-writing tables.
Intermediate level tables doesn't need to be removed after interlevel
compaction, as it will cause surplus split in the future. We can keep
the range if there are not many tables in the level.
Once level extension happens (i.e., the interlevel compaction to a new level), we can just move all tables in the previous level to the new level without re-writing tables.
Intermediate level tables doesn't need to be removed after interlevel compaction, as it will cause surplus split in the future. We can keep the range if there are not many tables in the level.