feat(config): allow to configure the rocksdb.min_write_buffer_number_to_merge

[nathanlo-hrt]

It's useful to configure this.

[sonarqubecloud]

Quality Gate failed

Failed conditions
29.2% Coverage on New Code (required ≥ 50%)

See analysis details on SonarQube Cloud

[nathanlo-hrt]

thanks for the review and edits! just fyi the edits would introduce a slight behavior change, since the original line of code reads

  options.min_write_buffer_number_to_merge = 2;

ie. a default value of 2, which will now be 1.

[git-hulk]

@nathanlo-hrt Oh? where's this assignment? It will default to 1 from the rocksdb source code: https://github.com/facebook/rocksdb/blob/7d80ea45442e84c25669db61cb7376ba0cd10ba5/include/rocksdb/advanced_options.h#L187

[nathanlo-hrt]

https://github.com/apache/kvrocks/blame/644c6b7666a93e1134641613fb715913ad02beaa/src/storage/storage.cc#L172C12-L172C12

[git-hulk]

https://github.com/apache/kvrocks/blame/644c6b7666a93e1134641613fb715913ad02beaa/src/storage/storage.cc#L172C12-L172C12

@nathanlo-hrt Thank you. I'm sorry that I didn't notice this option has ever been set in Kvrocks, but it should be good to keep the same default value with RocksDB.