Yanfei Lei

Hi @Myasuka, could you please help merge this PR?

@liming30 Thanks for your PR. Would you like to share some improvements if this PR merged via [flink-benchmarks](https://github.com/apache/flink-benchmarks).

@liming30 This optimization may increase the number of tombstones. As the [blog](https://rocksdb.org/blog/2018/11/21/delete-range.html) says, `deleteRange` would bring some regression on `Point Lookups` and `Range Scans`, could you please share the performance...

> Do you mean that the performance of Point Lookups and Range Scans should be verified again in Flink's benchmark? Not Flink's benchmark, the tests in Flink bechmark are fine-grained....

> I've been able to pin down the issue to https://github.com/apache/flink/blob/master/flink-runtime/src/main/java/org/apache/flink/runtime/state/OperatorStateRestoreOperation.java#L190 > > the problem is that the sorting breaks on empty state ... we should always restore in the...

> but ultimately we could remove it now. Yes, I think [acad43f](https://github.com/apache/flink/pull/24079/commits/acad43fa1458d4544840a7b28e2e752056e5e504) is a more thorough solution, and as you mentioned, it also solves the `the compressed representation might actually...

@Zakelly Thanks for the suggestion, I have removed file merging options from docs and annotated them with @\Experimental. please take another look! Many thanks!

@Zakelly I have rebased this PR, could you please take a look if you're free? thanks!

hi @wnnlyf, this looks a bit similar to https://github.com/facebook/rocksdb/issues/2531, could you please use a small Java program to try and load it to see if you can get more detailed...

> did you ever enable to run CI tests on circle? Hi @Myasuka, I have not modified the configuration of circleCI. It seems that 32(23+9) tests have been executed, and...