Compact RocksDB database after garbage collection.

Without this step, the page versions won't actually be removed, they're
just marked for deletion on the next RocksDB "merge" or "compact"
operation.

Author: Konstantin Knizhnik

pageserver/src/object_repository.rs

@@ -623,6 +623,7 @@ impl ObjectTimeline {
             result.elapsed = now.elapsed();
             info!("Garbage collection completed in {:?}: {} relations inspected, {} version histories truncated, {} versions deleted, {} relations dropped",
                   result.elapsed, &result.n_relations, &result.truncated, &result.deleted, &result.dropped);
+            self.obj_store.compact();
         }
         Ok(())
     }

pageserver/src/object_store.rs

@@ -68,4 +68,7 @@ pub trait ObjectStore: Send + Sync {
 
     /// Unlink object (used by GC). This mehod may actually delete object or just mark it for deletion.
     fn unlink(&self, key: &ObjectKey, lsn: Lsn) -> Result<()>;
+
+    // Compact storage and remove versions marged for deletion
+    fn compact(&self);
 }

pageserver/src/rocksdb_storage.rs

@@ -207,6 +207,10 @@ impl ObjectStore for RocksObjectStore {
             lsn,
         }))
     }
+
+    fn compact(&self) {
+        self.db.compact_range::<&[u8], &[u8]>(None, None);
+    }
 }
 
 impl RocksObjectStore {