List the compaction strategies available in ScyllaDB?

Compaction merges SSTables together to remove obsolete data and reduce read amplification; ScyllaDB supports several strategies suited to different workloads.

• Size-Tiered Compaction Strategy (STCS) - merges similarly-sized SSTables together; good default for write-heavy workloads.
• Leveled Compaction Strategy (LCS) - organizes SSTables into levels with bounded size; reduces read amplification and space overhead at the cost of more I/O during compaction, good for read-heavy workloads.
• Time-Window Compaction Strategy (TWCS) - groups SSTables by time window; ideal for time-series data with TTL-based expiration.
• Incremental Compaction Strategy (ICS) - a ScyllaDB-specific strategy that avoids the temporary doubling of disk space STCS needs during large compactions.

Picking the wrong strategy for the access pattern is a common source of either excessive read latency or excessive disk churn, so the strategy is usually revisited if compaction backlog or read amplification metrics look unhealthy.