diff --git a/tests/test_bit.py b/tests/test_bit.py
index 5a71642..c78ebc0 100644
--- a/tests/test_bit.py
+++ b/tests/test_bit.py
@@ -61,3 +61,33 @@ def test_repr(self):
     def test_equality(self):
         assert Bit([True, False, True]) == Bit([True, False, True])
         assert Bit([True, False, True]) != Bit([True, False, False])
+
+    def test_dimensions(self):
+        assert len(Bit([True, False, True]).to_list()) == 3
+
+    def test_to_db(self):
+        bit = Bit([True, False, True])
+        assert Bit._to_db(bit) == '101'
+
+    def test_to_db_invalid(self):
+        with pytest.raises(ValueError, match='expected bit'):
+            Bit._to_db([True, False, True])
+
+    def test_to_db_binary(self):
+        bit = Bit([True, False, True])
+        result = Bit._to_db_binary(bit)
+        assert result == bit.to_binary()
+
+    def test_to_db_binary_invalid(self):
+        with pytest.raises(ValueError, match='expected bit'):
+            Bit._to_db_binary([True, False, True])
+
+    def test_from_binary(self):
+        bit = Bit([True, False, True])
+        data = bit.to_binary()
+        result = Bit.from_binary(data)
+        assert result.to_list() == [True, False, True]
+
+    def test_from_binary_invalid(self):
+        with pytest.raises(ValueError, match='expected bytes'):
+            Bit.from_binary([1, 2, 3])
diff --git a/tests/test_half_vector.py b/tests/test_half_vector.py
index 78b4977..0b28820 100644
--- a/tests/test_half_vector.py
+++ b/tests/test_half_vector.py
@@ -57,3 +57,61 @@ def test_from_binary(self):
         assert vec.to_list() == [1.5, 2, 3]
         assert np.array_equal(vec.to_numpy(), [1.5, 2, 3])
         assert vec.to_binary() == data
+
+    def test_to_text(self):
+        vec = HalfVector([1.5, 2, 3])
+        assert vec.to_text() == '[1.5,2.0,3.0]'
+
+    def test_to_db(self):
+        vec = HalfVector([1, 2, 3])
+        assert HalfVector._to_db(vec) == '[1.0,2.0,3.0]'
+
+    def test_to_db_list(self):
+        assert HalfVector._to_db([1, 2, 3]) == '[1.0,2.0,3.0]'
+
+    def test_to_db_none(self):
+        assert HalfVector._to_db(None) is None
+
+    def test_to_db_dim(self):
+        vec = HalfVector([1, 2, 3])
+        assert HalfVector._to_db(vec, 3) == '[1.0,2.0,3.0]'
+
+    def test_to_db_dim_invalid(self):
+        vec = HalfVector([1, 2, 3])
+        with pytest.raises(ValueError, match='expected 2 dimensions, not 3'):
+            HalfVector._to_db(vec, 2)
+
+    def test_to_db_binary(self):
+        vec = HalfVector([1, 2, 3])
+        result = HalfVector._to_db_binary(vec)
+        assert result == vec.to_binary()
+
+    def test_to_db_binary_list(self):
+        result = HalfVector._to_db_binary([1, 2, 3])
+        assert result == HalfVector([1, 2, 3]).to_binary()
+
+    def test_to_db_binary_none(self):
+        assert HalfVector._to_db_binary(None) is None
+
+    def test_from_db_text(self):
+        result = HalfVector._from_db('[1.5,2,3]')
+        assert result.to_list() == [1.5, 2, 3]
+
+    def test_from_db_none(self):
+        assert HalfVector._from_db(None) is None
+
+    def test_from_db_halfvector(self):
+        vec = HalfVector([1, 2, 3])
+        assert HalfVector._from_db(vec) is vec
+
+    def test_from_db_binary(self):
+        data = pack('>HH3e', 3, 0, 1.5, 2, 3)
+        result = HalfVector._from_db_binary(data)
+        assert result.to_list() == [1.5, 2, 3]
+
+    def test_from_db_binary_none(self):
+        assert HalfVector._from_db_binary(None) is None
+
+    def test_from_db_binary_halfvector(self):
+        vec = HalfVector([1, 2, 3])
+        assert HalfVector._from_db_binary(vec) is vec
diff --git a/tests/test_sparse_vector.py b/tests/test_sparse_vector.py
index d580f32..1025ee3 100644
--- a/tests/test_sparse_vector.py
+++ b/tests/test_sparse_vector.py
@@ -110,3 +110,57 @@ def test_from_binary(self):
         assert vec.to_list() == [1.5, 0, 2, 0, 3, 0]
         assert np.array_equal(vec.to_numpy(), [1.5, 0, 2, 0, 3, 0])
         assert vec.to_binary() == data
+
+    def test_to_db(self):
+        vec = SparseVector([1, 0, 2, 0, 3, 0])
+        assert SparseVector._to_db(vec) == '{1:1.0,3:2.0,5:3.0}/6'
+
+    def test_to_db_list(self):
+        assert SparseVector._to_db([1, 0, 2, 0, 3, 0]) == '{1:1.0,3:2.0,5:3.0}/6'
+
+    def test_to_db_none(self):
+        assert SparseVector._to_db(None) is None
+
+    def test_to_db_dim(self):
+        vec = SparseVector([1, 0, 2, 0, 3, 0])
+        assert SparseVector._to_db(vec, 6) == '{1:1.0,3:2.0,5:3.0}/6'
+
+    def test_to_db_dim_invalid(self):
+        vec = SparseVector([1, 0, 2, 0, 3, 0])
+        with pytest.raises(ValueError, match='expected 5 dimensions, not 6'):
+            SparseVector._to_db(vec, 5)
+
+    def test_to_db_binary(self):
+        vec = SparseVector([1, 0, 2, 0, 3, 0])
+        result = SparseVector._to_db_binary(vec)
+        assert result == vec.to_binary()
+
+    def test_to_db_binary_list(self):
+        result = SparseVector._to_db_binary([1, 0, 2, 0, 3, 0])
+        assert result == SparseVector([1, 0, 2, 0, 3, 0]).to_binary()
+
+    def test_to_db_binary_none(self):
+        assert SparseVector._to_db_binary(None) is None
+
+    def test_from_db_text(self):
+        result = SparseVector._from_db('{1:1.5,3:2,5:3}/6')
+        assert result.to_list() == [1.5, 0, 2, 0, 3, 0]
+
+    def test_from_db_none(self):
+        assert SparseVector._from_db(None) is None
+
+    def test_from_db_sparsevector(self):
+        vec = SparseVector([1, 0, 2, 0, 3, 0])
+        assert SparseVector._from_db(vec) is vec
+
+    def test_from_db_binary(self):
+        data = pack('>iii3i3f', 6, 3, 0, 0, 2, 4, 1.5, 2, 3)
+        result = SparseVector._from_db_binary(data)
+        assert result.to_list() == [1.5, 0, 2, 0, 3, 0]
+
+    def test_from_db_binary_none(self):
+        assert SparseVector._from_db_binary(None) is None
+
+    def test_from_db_binary_sparsevector(self):
+        vec = SparseVector([1, 0, 2, 0, 3, 0])
+        assert SparseVector._from_db_binary(vec) is vec
diff --git a/tests/test_vector.py b/tests/test_vector.py
index e5a16fe..8612365 100644
--- a/tests/test_vector.py
+++ b/tests/test_vector.py
@@ -57,3 +57,61 @@ def test_from_binary(self):
         assert vec.to_list() == [1.5, 2, 3]
         assert np.array_equal(vec.to_numpy(), [1.5, 2, 3])
         assert vec.to_binary() == data
+
+    def test_to_text(self):
+        vec = Vector([1.5, 2, 3])
+        assert vec.to_text() == '[1.5,2.0,3.0]'
+
+    def test_to_db(self):
+        vec = Vector([1, 2, 3])
+        assert Vector._to_db(vec) == '[1.0,2.0,3.0]'
+
+    def test_to_db_list(self):
+        assert Vector._to_db([1, 2, 3]) == '[1.0,2.0,3.0]'
+
+    def test_to_db_none(self):
+        assert Vector._to_db(None) is None
+
+    def test_to_db_dim(self):
+        vec = Vector([1, 2, 3])
+        assert Vector._to_db(vec, 3) == '[1.0,2.0,3.0]'
+
+    def test_to_db_dim_invalid(self):
+        vec = Vector([1, 2, 3])
+        with pytest.raises(ValueError, match='expected 2 dimensions, not 3'):
+            Vector._to_db(vec, 2)
+
+    def test_to_db_binary(self):
+        vec = Vector([1, 2, 3])
+        result = Vector._to_db_binary(vec)
+        assert result == vec.to_binary()
+
+    def test_to_db_binary_list(self):
+        result = Vector._to_db_binary([1, 2, 3])
+        assert result == Vector([1, 2, 3]).to_binary()
+
+    def test_to_db_binary_none(self):
+        assert Vector._to_db_binary(None) is None
+
+    def test_from_db_text(self):
+        result = Vector._from_db('[1.5,2,3]')
+        assert np.array_equal(result, np.array([1.5, 2, 3], dtype=np.float32))
+
+    def test_from_db_none(self):
+        assert Vector._from_db(None) is None
+
+    def test_from_db_ndarray(self):
+        arr = np.array([1, 2, 3])
+        assert Vector._from_db(arr) is arr
+
+    def test_from_db_binary(self):
+        data = pack('>HH3f', 3, 0, 1.5, 2, 3)
+        result = Vector._from_db_binary(data)
+        assert np.array_equal(result, np.array([1.5, 2, 3], dtype=np.float32))
+
+    def test_from_db_binary_none(self):
+        assert Vector._from_db_binary(None) is None
+
+    def test_from_db_binary_ndarray(self):
+        arr = np.array([1, 2, 3])
+        assert Vector._from_db_binary(arr) is arr