RisingWave Community - What is the mechanism for compacting SST files in Hummock and how is it monitored by the meta service?

Hummock adapts the RocksDB's leveled-compaction strategy for compacting SST files.
When the number of SST files at the same level is too high, compaction is triggered to merge them.
The meta service monitors the compaction process in Hummock.

Example:

# Compaction process in Hummock
# Using RocksDB's leveled-compaction strategy

# Trigger compaction when the number of SST files is high
if num_sst_files_same_level > threshold:
    merge_sst_files()

# Meta service monitors the compaction process
monitor_compaction_process()