diff --git a/src/block/manager.rs b/src/block/manager.rs
index 41b2f02a..d1bf90d8 100644
--- a/src/block/manager.rs
+++ b/src/block/manager.rs
@@ -408,8 +408,8 @@ impl BlockManager {
 	}
 
 	/// Get number of items in the refcount table
-	pub fn rc_len(&self) -> Result<usize, Error> {
-		Ok(self.rc.rc_table.len()?)
+	pub fn rc_approximate_len(&self) -> Result<usize, Error> {
+		Ok(self.rc.rc_table.approximate_len()?)
 	}
 
 	/// Send command to start/stop/manager scrub worker
@@ -427,7 +427,7 @@ impl BlockManager {
 
 	/// List all resync errors
 	pub fn list_resync_errors(&self) -> Result<Vec<BlockResyncErrorInfo>, Error> {
-		let mut blocks = Vec::with_capacity(self.resync.errors.len()?);
+		let mut blocks = Vec::with_capacity(self.resync.errors.approximate_len()?);
 		for ent in self.resync.errors.iter()? {
 			let (hash, cnt) = ent?;
 			let cnt = ErrorCounter::decode(&cnt);
diff --git a/src/block/metrics.rs b/src/block/metrics.rs
index 2d41e365..c2ebb76b 100644
--- a/src/block/metrics.rs
+++ b/src/block/metrics.rs
@@ -50,7 +50,7 @@ impl BlockManagerMetrics {
 				.init(),
 			_rc_size: meter
 				.u64_value_observer("block.rc_size", move |observer| {
-					if let Ok(value) = rc_tree.len() {
+					if let Ok(value) = rc_tree.approximate_len() {
 						observer.observe(value as u64, &[])
 					}
 				})
@@ -58,7 +58,7 @@ impl BlockManagerMetrics {
 				.init(),
 			_resync_queue_len: meter
 				.u64_value_observer("block.resync_queue_length", move |observer| {
-					if let Ok(value) = resync_queue.len() {
+					if let Ok(value) = resync_queue.approximate_len() {
 						observer.observe(value as u64, &[]);
 					}
 				})
@@ -68,7 +68,7 @@ impl BlockManagerMetrics {
 				.init(),
 			_resync_errored_blocks: meter
 				.u64_value_observer("block.resync_errored_blocks", move |observer| {
-					if let Ok(value) = resync_errors.len() {
+					if let Ok(value) = resync_errors.approximate_len() {
 						observer.observe(value as u64, &[]);
 					}
 				})
diff --git a/src/block/resync.rs b/src/block/resync.rs
index b476a0b8..004f6b48 100644
--- a/src/block/resync.rs
+++ b/src/block/resync.rs
@@ -106,13 +106,13 @@ impl BlockResyncManager {
 	}
 
 	/// Get length of resync queue
-	pub fn queue_len(&self) -> Result<usize, Error> {
-		Ok(self.queue.len()?)
+	pub fn queue_approximate_len(&self) -> Result<usize, Error> {
+		Ok(self.queue.approximate_len()?)
 	}
 
 	/// Get number of blocks that have an error
-	pub fn errors_len(&self) -> Result<usize, Error> {
-		Ok(self.errors.len()?)
+	pub fn errors_approximate_len(&self) -> Result<usize, Error> {
+		Ok(self.errors.approximate_len()?)
 	}
 
 	/// Clear the error counter for a block and put it in queue immediately
@@ -548,9 +548,11 @@ impl Worker for ResyncWorker {
 		}
 
 		WorkerStatus {
-			queue_length: Some(self.manager.resync.queue_len().unwrap_or(0) as u64),
+			queue_length: Some(self.manager.resync.queue_approximate_len().unwrap_or(0) as u64),
 			tranquility: Some(tranquility),
-			persistent_errors: Some(self.manager.resync.errors_len().unwrap_or(0) as u64),
+			persistent_errors: Some(
+				self.manager.resync.errors_approximate_len().unwrap_or(0) as u64
+			),
 			..Default::default()
 		}
 	}
diff --git a/src/db/fjall_adapter.rs b/src/db/fjall_adapter.rs
index d91ef12f..d6a41e9e 100644
--- a/src/db/fjall_adapter.rs
+++ b/src/db/fjall_adapter.rs
@@ -132,10 +132,14 @@ impl IDb for FjallDb {
 		}
 	}
 
-	fn len(&self, tree_idx: usize) -> Result<usize> {
+	fn approximate_len(&self, tree_idx: usize) -> Result<usize> {
+		let tree = self.get_tree(tree_idx)?;
+		Ok(tree.approximate_len())
+	}
+	fn is_empty(&self, tree_idx: usize) -> Result<bool> {
 		let tree = self.get_tree(tree_idx)?;
 		let tx = self.keyspace.read_tx();
-		Ok(tx.len(&tree)?)
+		Ok(tx.is_empty(&tree)?)
 	}
 
 	fn insert(&self, tree_idx: usize, key: &[u8], value: &[u8]) -> Result<()> {
diff --git a/src/db/lib.rs b/src/db/lib.rs
index 3454c759..5ac16da8 100644
--- a/src/db/lib.rs
+++ b/src/db/lib.rs
@@ -154,7 +154,7 @@ impl Db {
 		let tree_names = other.list_trees()?;
 		for name in tree_names {
 			let tree = self.open_tree(&name)?;
-			if tree.len()? > 0 {
+			if !tree.is_empty()? {
 				return Err(Error(format!("tree {} already contains data", name).into()));
 			}
 
@@ -196,8 +196,12 @@ impl Tree {
 		self.0.get(self.1, key.as_ref())
 	}
 	#[inline]
-	pub fn len(&self) -> Result<usize> {
-		self.0.len(self.1)
+	pub fn approximate_len(&self) -> Result<usize> {
+		self.0.approximate_len(self.1)
+	}
+	#[inline]
+	pub fn is_empty(&self) -> Result<bool> {
+		self.0.is_empty(self.1)
 	}
 
 	#[inline]
@@ -335,7 +339,8 @@ pub(crate) trait IDb: Send + Sync {
 	fn snapshot(&self, path: &PathBuf) -> Result<()>;
 
 	fn get(&self, tree: usize, key: &[u8]) -> Result<Option<Value>>;
-	fn len(&self, tree: usize) -> Result<usize>;
+	fn approximate_len(&self, tree: usize) -> Result<usize>;
+	fn is_empty(&self, tree: usize) -> Result<bool>;
 
 	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()>;
 	fn remove(&self, tree: usize, key: &[u8]) -> Result<()>;
diff --git a/src/db/lmdb_adapter.rs b/src/db/lmdb_adapter.rs
index bd85f1b4..cbbce2f8 100644
--- a/src/db/lmdb_adapter.rs
+++ b/src/db/lmdb_adapter.rs
@@ -126,11 +126,16 @@ impl IDb for LmdbDb {
 		}
 	}
 
-	fn len(&self, tree: usize) -> Result<usize> {
+	fn approximate_len(&self, tree: usize) -> Result<usize> {
 		let tree = self.get_tree(tree)?;
 		let tx = self.db.read_txn()?;
 		Ok(tree.len(&tx)?.try_into().unwrap())
 	}
+	fn is_empty(&self, tree: usize) -> Result<bool> {
+		let tree = self.get_tree(tree)?;
+		let tx = self.db.read_txn()?;
+		Ok(tree.is_empty(&tx)?)
+	}
 
 	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()> {
 		let tree = self.get_tree(tree)?;
diff --git a/src/db/sqlite_adapter.rs b/src/db/sqlite_adapter.rs
index ce6412b6..eee8b15d 100644
--- a/src/db/sqlite_adapter.rs
+++ b/src/db/sqlite_adapter.rs
@@ -160,7 +160,7 @@ impl IDb for SqliteDb {
 		self.internal_get(&self.db.get()?, &tree, key)
 	}
 
-	fn len(&self, tree: usize) -> Result<usize> {
+	fn approximate_len(&self, tree: usize) -> Result<usize> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
 
@@ -172,6 +172,10 @@ impl IDb for SqliteDb {
 		}
 	}
 
+	fn is_empty(&self, tree: usize) -> Result<bool> {
+		Ok(self.approximate_len(tree)? == 0)
+	}
+
 	fn insert(&self, tree: usize, key: &[u8], value: &[u8]) -> Result<()> {
 		let tree = self.get_tree(tree)?;
 		let db = self.db.get()?;
diff --git a/src/db/test.rs b/src/db/test.rs
index 08ce1dda..1e649719 100644
--- a/src/db/test.rs
+++ b/src/db/test.rs
@@ -14,7 +14,7 @@ fn test_suite(db: Db) {
 
 	assert!(tree.insert(ka, va).is_ok());
 	assert_eq!(tree.get(ka).unwrap().unwrap(), va);
-	assert_eq!(tree.len().unwrap(), 1);
+	assert_eq!(tree.iter().unwrap().count(), 1);
 
 	// ---- test transaction logic ----
 
diff --git a/src/garage/admin/mod.rs b/src/garage/admin/mod.rs
index 3bbc2b86..6ae8fa88 100644
--- a/src/garage/admin/mod.rs
+++ b/src/garage/admin/mod.rs
@@ -219,7 +219,7 @@ impl AdminRpcHandler {
 
 		// Gather block manager statistics
 		writeln!(&mut ret, "\nBlock manager stats:").unwrap();
-		let rc_len = self.garage.block_manager.rc_len()?.to_string();
+		let rc_len = self.garage.block_manager.rc_approximate_len()?.to_string();
 
 		writeln!(
 			&mut ret,
@@ -230,13 +230,13 @@ impl AdminRpcHandler {
 		writeln!(
 			&mut ret,
 			"  resync queue length: {}",
-			self.garage.block_manager.resync.queue_len()?
+			self.garage.block_manager.resync.queue_approximate_len()?
 		)
 		.unwrap();
 		writeln!(
 			&mut ret,
 			"  blocks with resync errors: {}",
-			self.garage.block_manager.resync.errors_len()?
+			self.garage.block_manager.resync.errors_approximate_len()?
 		)
 		.unwrap();
 
@@ -346,16 +346,21 @@ impl AdminRpcHandler {
 		F: TableSchema + 'static,
 		R: TableReplication + 'static,
 	{
-		let data_len = t.data.store.len().map_err(GarageError::from)?.to_string();
-		let mkl_len = t.merkle_updater.merkle_tree_len()?.to_string();
+		let data_len = t
+			.data
+			.store
+			.approximate_len()
+			.map_err(GarageError::from)?
+			.to_string();
+		let mkl_len = t.merkle_updater.merkle_tree_approximate_len()?.to_string();
 
 		Ok(format!(
 			"  {}\t{}\t{}\t{}\t{}",
 			F::TABLE_NAME,
 			data_len,
 			mkl_len,
-			t.merkle_updater.todo_len()?,
-			t.data.gc_todo_len()?
+			t.merkle_updater.todo_approximate_len()?,
+			t.data.gc_todo_approximate_len()?
 		))
 	}
 
diff --git a/src/model/s3/lifecycle_worker.rs b/src/model/s3/lifecycle_worker.rs
index bb10ba48..af00437e 100644
--- a/src/model/s3/lifecycle_worker.rs
+++ b/src/model/s3/lifecycle_worker.rs
@@ -121,13 +121,13 @@ impl Worker for LifecycleWorker {
 				mpu_aborted,
 				..
 			} => {
-				let n_objects = self.garage.object_table.data.store.len().ok();
+				let n_objects = self.garage.object_table.data.store.approximate_len().ok();
 				let progress = match n_objects {
-					None => "...".to_string(),
-					Some(total) => format!(
+					Some(total) if total > 0 => format!(
 						"~{:.2}%",
 						100. * std::cmp::min(*counter, total) as f32 / total as f32
 					),
+					_ => "...".to_string(),
 				};
 				WorkerStatus {
 					progress: Some(progress),
diff --git a/src/table/data.rs b/src/table/data.rs
index 09f4e008..1d0308ce 100644
--- a/src/table/data.rs
+++ b/src/table/data.rs
@@ -367,7 +367,7 @@ impl<F: TableSchema, R: TableReplication> TableData<F, R> {
 		}
 	}
 
-	pub fn gc_todo_len(&self) -> Result<usize, Error> {
-		Ok(self.gc_todo.len()?)
+	pub fn gc_todo_approximate_len(&self) -> Result<usize, Error> {
+		Ok(self.gc_todo.approximate_len()?)
 	}
 }
diff --git a/src/table/gc.rs b/src/table/gc.rs
index 28ea119d..1f30bd76 100644
--- a/src/table/gc.rs
+++ b/src/table/gc.rs
@@ -313,7 +313,7 @@ impl<F: TableSchema, R: TableReplication> Worker for GcWorker<F, R> {
 
 	fn status(&self) -> WorkerStatus {
 		WorkerStatus {
-			queue_length: Some(self.gc.data.gc_todo_len().unwrap_or(0) as u64),
+			queue_length: Some(self.gc.data.gc_todo_approximate_len().unwrap_or(0) as u64),
 			..Default::default()
 		}
 	}
diff --git a/src/table/merkle.rs b/src/table/merkle.rs
index 596d5805..7ba1f007 100644
--- a/src/table/merkle.rs
+++ b/src/table/merkle.rs
@@ -287,12 +287,12 @@ impl<F: TableSchema, R: TableReplication> MerkleUpdater<F, R> {
 		MerkleNode::decode_opt(&ent)
 	}
 
-	pub fn merkle_tree_len(&self) -> Result<usize, Error> {
-		Ok(self.data.merkle_tree.len()?)
+	pub fn merkle_tree_approximate_len(&self) -> Result<usize, Error> {
+		Ok(self.data.merkle_tree.approximate_len()?)
 	}
 
-	pub fn todo_len(&self) -> Result<usize, Error> {
-		Ok(self.data.merkle_todo.len()?)
+	pub fn todo_approximate_len(&self) -> Result<usize, Error> {
+		Ok(self.data.merkle_todo.approximate_len()?)
 	}
 }
 
@@ -306,7 +306,7 @@ impl<F: TableSchema, R: TableReplication> Worker for MerkleWorker<F, R> {
 
 	fn status(&self) -> WorkerStatus {
 		WorkerStatus {
-			queue_length: Some(self.0.todo_len().unwrap_or(0) as u64),
+			queue_length: Some(self.0.todo_approximate_len().unwrap_or(0) as u64),
 			..Default::default()
 		}
 	}
diff --git a/src/table/metrics.rs b/src/table/metrics.rs
index 7bb0959a..78593202 100644
--- a/src/table/metrics.rs
+++ b/src/table/metrics.rs
@@ -34,7 +34,7 @@ impl TableMetrics {
 				.u64_value_observer(
 					"table.size",
 					move |observer| {
-						if let Ok(value) = store.len() {
+						if let Ok(value) = store.approximate_len() {
 							observer.observe(
 								value as u64,
 								&[KeyValue::new("table_name", table_name)],
@@ -48,7 +48,7 @@ impl TableMetrics {
 				.u64_value_observer(
 					"table.merkle_tree_size",
 					move |observer| {
-						if let Ok(value) = merkle_tree.len() {
+						if let Ok(value) = merkle_tree.approximate_len() {
 							observer.observe(
 								value as u64,
 								&[KeyValue::new("table_name", table_name)],
@@ -62,7 +62,7 @@ impl TableMetrics {
 				.u64_value_observer(
 					"table.merkle_updater_todo_queue_length",
 					move |observer| {
-						if let Ok(v) = merkle_todo.len() {
+						if let Ok(v) = merkle_todo.approximate_len() {
 							observer.observe(
 								v as u64,
 								&[KeyValue::new("table_name", table_name)],
@@ -76,7 +76,7 @@ impl TableMetrics {
 				.u64_value_observer(
 					"table.gc_todo_queue_length",
 					move |observer| {
-                        if let Ok(value) = gc_todo.len() {
+                        if let Ok(value) = gc_todo.approximate_len() {
                             observer.observe(
                                 value as u64,
                                 &[KeyValue::new("table_name", table_name)],
diff --git a/src/table/queue.rs b/src/table/queue.rs
index ffe0a4a7..7ef1f16e 100644
--- a/src/table/queue.rs
+++ b/src/table/queue.rs
@@ -27,7 +27,7 @@ impl<F: TableSchema, R: TableReplication> Worker for InsertQueueWorker<F, R> {
 
 	fn status(&self) -> WorkerStatus {
 		WorkerStatus {
-			queue_length: Some(self.0.data.insert_queue.len().unwrap_or(0) as u64),
+			queue_length: Some(self.0.data.insert_queue.approximate_len().unwrap_or(0) as u64),
 			..Default::default()
 		}
 	}