gc_grace_seconds is a table-level ScyllaDB setting that specifies how long a tombstone must remain before compaction may remove it. Scylla defaults this period to 10 days. section 6.2.3
The delay gives tombstones time to reach all replicas. Removing one too early can allow a deleted value to reappear when a node still holds the old data; keeping it too long consumes storage. section 6.2.3 section 6.6
Use the setting with these operational considerations:
- Choose a value that balances replica synchronization against unnecessary tombstone accumulation. section 6.2.3
- Repair the cluster within the grace period so replicas synchronize tombstones before compaction can remove them. section 6.2.3 section 6.6
Figure 6.6 Compaction combines multiple SSTables into a newer SSTable, skipping obsolete rows and eligible-for-deletion tombstones.
Compaction combines SSTables and skips tombstones that have become eligible for removal. section 6.2.3
