Discussion：Why does the tombstone delete key still exists in the SST, but the insert key no longer exist in the SST?

[jianwei1216]

问题：rocksdb 通过 sst_dump scan 所有 SST 文件，发现有的 key 只有 tombstone delete key ，但没有历时 insert key，请问 tombstone delete key 在 compaction 时，为什么没有和 insert key 一起清理掉？

Question: Rocksdb scanned all SST files through sst_dump and found that some keys only had a tombstone delete key, but not an insert key. May I ask why the tombstone delete key was not cleared together with the insert key during compaction?

rocksdb version: v7.9.2

Can you answer my questions and clarify my doubts?
Because my understanding is that the tombstone delete key should disappear at the same time as the insert key

sst_dump --file=<path_to_db> --command=scan

[jianwei1216]

@cbi42