diff --git a/tools/iface/src/db.rs b/tools/iface/src/db.rs
index e6f31a3..50b2720 100644
--- a/tools/iface/src/db.rs
+++ b/tools/iface/src/db.rs
@@ -13,6 +13,8 @@ pub trait Database {
     fn names<'a>(&'a self) -> Vec<Vec<u8>>;
 
     fn segment<'a>(&'a mut self, name: Vec<u8>) -> Option<Box<dyn Segment + 'a>>; // change return type to Result
+
+    fn flush(&mut self);
 }
 
 pub trait Segment {
@@ -54,8 +56,10 @@ pub fn copy_database(
         }
 
         drop(dst_seg);
-
         drop(src_seg_iter);
+        drop(src_seg);
+
+        dst.flush();
     }
 
     Ok(())
diff --git a/tools/iface/src/db/heed.rs b/tools/iface/src/db/heed.rs
index 8dc24f6..28eb481 100644
--- a/tools/iface/src/db/heed.rs
+++ b/tools/iface/src/db/heed.rs
@@ -64,6 +64,10 @@ impl Database for HeedDB {
             .map(|(k, _)| k)
             .collect_vec()
     }
+
+    fn flush(&mut self) {
+        // NOOP
+    }
 }
 pub struct HeedSegment {
     env: heed::Env,
diff --git a/tools/iface/src/db/rocksdb.rs b/tools/iface/src/db/rocksdb.rs
index d50e979..63a3594 100644
--- a/tools/iface/src/db/rocksdb.rs
+++ b/tools/iface/src/db/rocksdb.rs
@@ -80,6 +80,10 @@ impl Database for RocksDB {
             .map(|v| v.as_bytes().to_vec())
             .collect()
     }
+
+    fn flush(&mut self) {
+        self.rocks.flush().unwrap()
+    }
 }
 
 impl Drop for RocksDB {
diff --git a/tools/iface/src/db/sled.rs b/tools/iface/src/db/sled.rs
index db25b03..f2d465f 100644
--- a/tools/iface/src/db/sled.rs
+++ b/tools/iface/src/db/sled.rs
@@ -33,6 +33,10 @@ impl Database for SledDB {
             .ok()
             .map(|t| -> Box<dyn Segment> { Box::new(t) })
     }
+
+    fn flush(&mut self) {
+        self.0.flush().unwrap();
+    }
 }
 
 impl Segment for Tree {
diff --git a/tools/iface/src/db/sqlite.rs b/tools/iface/src/db/sqlite.rs
index ec6c03e..458e25b 100644
--- a/tools/iface/src/db/sqlite.rs
+++ b/tools/iface/src/db/sqlite.rs
@@ -64,6 +64,10 @@ impl Database for SqliteDB {
             name: string,
         }))
     }
+
+    fn flush(&mut self) {
+        // NOOP
+    }
 }
 
 pub struct SqliteSegment<'a> {