diff --git a/cozo-core/src/fixed_rule/mod.rs b/cozo-core/src/fixed_rule/mod.rs
index 01f140f6..feca8c99 100644
--- a/cozo-core/src/fixed_rule/mod.rs
+++ b/cozo-core/src/fixed_rule/mod.rs
@@ -664,8 +664,8 @@ pub(crate) struct FixedRuleHandle {
 }
 
 lazy_static! {
-    pub(crate) static ref DEFAULT_FIXED_RULES: Arc<BTreeMap<String, Arc<Box<dyn FixedRule>>>> = {
-        Arc::new(BTreeMap::from([
+    pub(crate) static ref DEFAULT_FIXED_RULES: BTreeMap<String, Arc<Box<dyn FixedRule>>> = {
+        BTreeMap::from([
             #[cfg(feature = "graph-algo")]
             (
                 "ClusteringCoefficients".to_string(),
@@ -792,7 +792,7 @@ lazy_static! {
                 "Constant".to_string(),
                 Arc::<Box<dyn FixedRule>>::new(Box::new(Constant)),
             ),
-        ]))
+        ])
     };
 }
 
diff --git a/cozo-core/src/lib.rs b/cozo-core/src/lib.rs
index f3274c5c..1d9104ea 100644
--- a/cozo-core/src/lib.rs
+++ b/cozo-core/src/lib.rs
@@ -80,7 +80,6 @@ pub(crate) mod runtime;
 pub(crate) mod storage;
 pub(crate) mod utils;
 
-#[derive(Clone)]
 /// A dispatcher for concrete storage implementations, wrapping [Db]. This is done so that
 /// client code does not have to deal with generic code constantly. You may prefer to use
 /// [Db] directly, especially if you provide a custom storage engine.
@@ -412,7 +411,7 @@ impl DbInstance {
     }
     /// Dispatcher method. See [crate::Db::register_fixed_rule].
     pub fn register_fixed_rule(
-        &mut self,
+        &self,
         name: String,
         rule_impl: Box<dyn FixedRule>,
     ) -> Result<()> {
diff --git a/cozo-core/src/query/stored.rs b/cozo-core/src/query/stored.rs
index 30c1bb82..c1f36a80 100644
--- a/cozo-core/src/query/stored.rs
+++ b/cozo-core/src/query/stored.rs
@@ -79,7 +79,7 @@ impl<'a> SessionTx<'a> {
                 }
                 for trigger in &old_handle.replace_triggers {
                     let program =
-                        parse_script(trigger, &Default::default(), &db.algorithms, cur_vld)?
+                        parse_script(trigger, &Default::default(), &db.algorithms.read().unwrap(), cur_vld)?
                             .get_single_program()?;
 
                     let (_, cleanups) = db
@@ -203,7 +203,7 @@ impl<'a> SessionTx<'a> {
                             let mut program = parse_script(
                                 trigger,
                                 &Default::default(),
-                                &db.algorithms,
+                                &db.algorithms.read().unwrap(),
                                 cur_vld,
                             )?
                             .get_single_program()?;
@@ -482,7 +482,7 @@ impl<'a> SessionTx<'a> {
                             let mut program = parse_script(
                                 trigger,
                                 &Default::default(),
-                                &db.algorithms,
+                                &db.algorithms.read().unwrap(),
                                 cur_vld,
                             )?
                             .get_single_program()?;
diff --git a/cozo-core/src/runtime/db.rs b/cozo-core/src/runtime/db.rs
index 7e01face..dc77eeee 100644
--- a/cozo-core/src/runtime/db.rs
+++ b/cozo-core/src/runtime/db.rs
@@ -82,22 +82,21 @@ pub struct DbManifest {
 }
 
 /// The database object of Cozo.
-#[derive(Clone)]
 pub struct Db<S> {
     pub(crate) db: S,
     temp_db: TempStorage,
     relation_store_id: Arc<AtomicU64>,
-    queries_count: Arc<AtomicU64>,
+    queries_count: AtomicU64,
     running_queries: Arc<Mutex<BTreeMap<u64, RunningQueryHandle>>>,
-    pub(crate) algorithms: Arc<BTreeMap<String, Arc<Box<dyn FixedRule>>>>,
+    pub(crate) algorithms: ShardedLock<BTreeMap<String, Arc<Box<dyn FixedRule>>>>,
     #[cfg(not(target_arch = "wasm32"))]
-    callback_count: Arc<AtomicU32>,
+    callback_count: AtomicU32,
     #[cfg(not(target_arch = "wasm32"))]
     pub(crate) callback_sender:
         Sender<(SmartString<LazyCompact>, CallbackOp, NamedRows, NamedRows)>,
     #[cfg(not(target_arch = "wasm32"))]
     pub(crate) event_callbacks: Arc<ShardedLock<EventCallbackRegistry>>,
-    relation_locks: Arc<ShardedLock<BTreeMap<SmartString<LazyCompact>, Arc<ShardedLock<()>>>>>,
+    relation_locks: ShardedLock<BTreeMap<SmartString<LazyCompact>, Arc<ShardedLock<()>>>>,
 }
 
 impl<S> Debug for Db<S> {
@@ -189,18 +188,18 @@ impl<'s, S: Storage<'s>> Db<S> {
         let ret = Self {
             db: storage,
             temp_db: Default::default(),
-            relation_store_id: Arc::new(Default::default()),
-            queries_count: Arc::new(Default::default()),
-            running_queries: Arc::new(Mutex::new(Default::default())),
-            algorithms: DEFAULT_FIXED_RULES.clone(),
+            relation_store_id: Default::default(),
+            queries_count: Default::default(),
+            running_queries: Default::default(),
+            algorithms: ShardedLock::new(DEFAULT_FIXED_RULES.clone()),
             #[cfg(not(target_arch = "wasm32"))]
-            callback_count: Arc::new(Default::default()),
+            callback_count: Default::default(),
             #[cfg(not(target_arch = "wasm32"))]
             callback_sender: sender,
             // callback_receiver: Arc::new(receiver),
             #[cfg(not(target_arch = "wasm32"))]
-            event_callbacks: Arc::new(Default::default()),
-            relation_locks: Arc::new(Default::default()),
+            event_callbacks: Default::default(),
+            relation_locks: Default::default(),
         };
         #[cfg(not(target_arch = "wasm32"))]
         {
@@ -549,16 +548,12 @@ impl<'s, S: Storage<'s>> Db<S> {
         }
     }
     /// Register a custom fixed rule implementation.
-    ///
-    /// You must register fixed rules BEFORE you clone the database,
-    /// otherwise already cloned instances will not get the new fixed rule.
     pub fn register_fixed_rule(
-        &mut self,
+        &self,
         name: String,
         rule_impl: Box<dyn FixedRule>,
     ) -> Result<()> {
-        let new = Arc::make_mut(&mut self.algorithms);
-        match new.entry(name) {
+        match self.algorithms.write().unwrap().entry(name) {
             Entry::Vacant(ent) => {
                 ent.insert(Arc::new(rule_impl));
                 Ok(())
@@ -713,7 +708,7 @@ impl<'s, S: Storage<'s>> Db<S> {
         param_pool: &BTreeMap<String, DataValue>,
         cur_vld: ValidityTs,
     ) -> Result<NamedRows> {
-        match parse_script(payload, param_pool, &self.algorithms, cur_vld)? {
+        match parse_script(payload, param_pool, &self.algorithms.read().unwrap(), cur_vld)? {
             CozoScript::Single(p) => self.execute_single(cur_vld, p),
             CozoScript::Imperative(ps) => self.execute_imperative(cur_vld, &ps),
             CozoScript::Sys(op) => self.run_sys_op(op),
diff --git a/cozo-core/src/storage/mem.rs b/cozo-core/src/storage/mem.rs
index 44892087..c950e81f 100644
--- a/cozo-core/src/storage/mem.rs
+++ b/cozo-core/src/storage/mem.rs
@@ -36,7 +36,7 @@ pub fn new_cozo_mem() -> Result<crate::Db<MemStorage>> {
 }
 
 /// The non-persistent storage
-#[derive(Clone, Default)]
+#[derive(Default)]
 pub struct MemStorage {
     store: Arc<ShardedLock<BTreeMap<Vec<u8>, Vec<u8>>>>,
 }
diff --git a/cozo-core/src/storage/rocks.rs b/cozo-core/src/storage/rocks.rs
index 198669f2..9a15aa9a 100644
--- a/cozo-core/src/storage/rocks.rs
+++ b/cozo-core/src/storage/rocks.rs
@@ -111,7 +111,6 @@ pub fn new_cozo_rocksdb(path: impl AsRef<Path>) -> Result<Db<RocksDbStorage>> {
 }
 
 /// RocksDB storage engine
-#[derive(Clone)]
 pub struct RocksDbStorage {
     db: RocksDb,
 }
diff --git a/cozo-core/src/storage/sled.rs b/cozo-core/src/storage/sled.rs
index c48a837f..5b00c6f2 100644
--- a/cozo-core/src/storage/sled.rs
+++ b/cozo-core/src/storage/sled.rs
@@ -33,7 +33,6 @@ pub fn new_cozo_sled(path: impl AsRef<Path>) -> Result<crate::Db<SledStorage>> {
 }
 
 /// Storage engine using Sled
-#[derive(Clone)]
 pub struct SledStorage {
     db: Db,
 }
diff --git a/cozo-core/src/storage/sqlite.rs b/cozo-core/src/storage/sqlite.rs
index c39ae0f1..28e5aed6 100644
--- a/cozo-core/src/storage/sqlite.rs
+++ b/cozo-core/src/storage/sqlite.rs
@@ -22,11 +22,10 @@ use crate::storage::{Storage, StoreTx};
 use crate::utils::swap_option_result;
 
 /// The Sqlite storage engine
-#[derive(Clone)]
 pub struct SqliteStorage {
     lock: Arc<ShardedLock<()>>,
     name: PathBuf,
-    pool: Arc<Mutex<Vec<ConnectionWithFullMutex>>>,
+    pool: Mutex<Vec<ConnectionWithFullMutex>>,
 }
 
 /// Create a sqlite backed database.
@@ -50,9 +49,9 @@ pub fn new_cozo_sqlite(path: impl AsRef<Path>) -> Result<crate::Db<SqliteStorage
     while statement.next().into_diagnostic()? != State::Done {}
 
     let ret = crate::Db::new(SqliteStorage {
-        lock: Arc::new(Default::default()),
+        lock: Default::default(),
         name: PathBuf::from(path.as_ref()),
-        pool: Arc::new(Mutex::new(vec![])),
+        pool: Mutex::new(vec![]),
     })?;
 
     ret.initialize()?;
diff --git a/cozo-core/src/storage/temp.rs b/cozo-core/src/storage/temp.rs
index 201426e0..dc23ffe3 100644
--- a/cozo-core/src/storage/temp.rs
+++ b/cozo-core/src/storage/temp.rs
@@ -17,7 +17,7 @@ use crate::runtime::relation::decode_tuple_from_kv;
 use crate::storage::mem::SkipIterator;
 use crate::storage::{Storage, StoreTx};
 
-#[derive(Clone, Default)]
+#[derive(Default)]
 pub(crate) struct TempStorage;
 
 impl<'s> Storage<'s> for TempStorage {
diff --git a/cozo-core/src/storage/tikv.rs b/cozo-core/src/storage/tikv.rs
index 3b5370ca..ce1971a5 100644
--- a/cozo-core/src/storage/tikv.rs
+++ b/cozo-core/src/storage/tikv.rs
@@ -52,7 +52,6 @@ lazy_static! {
 }
 
 /// Storage engine based on TiKV
-#[derive(Clone)]
 pub struct TiKvStorage {
     client: Arc<TransactionClient>,
     raw_client: Arc<RawClient>,
diff --git a/cozorocks/bridge/db.cpp b/cozorocks/bridge/db.cpp
index 4c442a5d..bb05b10d 100644
--- a/cozorocks/bridge/db.cpp
+++ b/cozorocks/bridge/db.cpp
@@ -53,7 +53,7 @@ ColumnFamilyOptions default_cf_options() {
     return options;
 }
 
-shared_ptr <RocksDbBridge> open_db(const DbOpts &opts, RocksDbStatus &status) {
+unique_ptr <RocksDbBridge> open_db(const DbOpts &opts, RocksDbStatus &status) {
     auto options = default_db_options();
 
     shared_ptr<Cache> cache = nullptr;
@@ -120,7 +120,7 @@ shared_ptr <RocksDbBridge> open_db(const DbOpts &opts, RocksDbStatus &status) {
     }
     options.create_missing_column_families = true;
 
-    shared_ptr <RocksDbBridge> db = make_shared<RocksDbBridge>();
+    unique_ptr <RocksDbBridge> db = make_unique<RocksDbBridge>();
 
     db->db_path = convert_vec_to_string(opts.db_path);
 
diff --git a/cozorocks/bridge/db.h b/cozorocks/bridge/db.h
index fc7e462a..7133d3ce 100644
--- a/cozorocks/bridge/db.h
+++ b/cozorocks/bridge/db.h
@@ -117,7 +117,7 @@ struct RocksDbBridge {
     ~RocksDbBridge();
 };
 
-shared_ptr<RocksDbBridge>
+unique_ptr<RocksDbBridge>
 open_db(const DbOpts &opts, RocksDbStatus &status);
 
 #endif //COZOROCKS_DB_H
diff --git a/cozorocks/src/bridge/db.rs b/cozorocks/src/bridge/db.rs
index f65998c1..19352461 100644
--- a/cozorocks/src/bridge/db.rs
+++ b/cozorocks/src/bridge/db.rs
@@ -133,9 +133,8 @@ impl DbBuilder {
     }
 }
 
-#[derive(Clone)]
 pub struct RocksDb {
-    inner: SharedPtr<RocksDbBridge>,
+    inner: UniquePtr<RocksDbBridge>,
 }
 
 impl RocksDb {
diff --git a/cozorocks/src/bridge/mod.rs b/cozorocks/src/bridge/mod.rs
index dabccb4f..576fcbe2 100644
--- a/cozorocks/src/bridge/mod.rs
+++ b/cozorocks/src/bridge/mod.rs
@@ -125,7 +125,7 @@ pub(crate) mod ffi {
         fn open_db(
             builder: &DbOpts,
             status: &mut RocksDbStatus,
-        ) -> SharedPtr<RocksDbBridge>;
+        ) -> UniquePtr<RocksDbBridge>;
         fn transact(self: &RocksDbBridge) -> UniquePtr<TxBridge>;
         fn del_range(
             self: &RocksDbBridge,