Audrius is a better programmer than me.

tablite/base.py

@@ -1683,7 +1683,9 @@ def display_dict(self, slice_=None, blanks=None, dtype=False):
         def datatype(col):  # PRIVATE
             """creates label for column datatype."""
             types = col.types()
-            if len(types) == 1:
+            if len(types) == 0:
+                typ = "empty"
+            elif len(types) == 1:
                 dt, _ = types.popitem()
                 typ = dt.__name__
             else:

tablite/core.py

@@ -729,7 +729,7 @@ def column_select(self, cols: list[ColumnSelectorDict], tqdm=_tqdm, TaskManager=
         """
         return _column_select(self, cols, tqdm, TaskManager)
 
-    def join(self, other, left_keys, right_keys, left_columns, right_columns, kind="inner", merge_keys=False, tqdm=_tqdm, pbar=None):
+    def join(self, other, left_keys, right_keys, left_columns=None, right_columns=None, kind="inner", merge_keys=False, tqdm=_tqdm, pbar=None):
         """
         short-cut for all join functions.
         kind: 'inner', 'left', 'outer', 'cross'

tablite/joins.py

@@ -171,14 +171,6 @@ def _jointype_check(T, other, left_keys, right_keys, left_columns, right_columns
     if len(left_keys) != len(right_keys):
         raise ValueError(f"Keys do not have same length: \n{left_keys}, \n{right_keys}")
 
-    for L, R in zip(left_keys, right_keys):
-        Lcol, Rcol = T[L], other[R]
-        if not set(Lcol.types()).intersection(set(Rcol.types())):
-            left_types = tuple(t.__name__ for t in list(Lcol.types().keys()))
-            right_types = tuple(t.__name__ for t in list(Rcol.types().keys()))
-            e = f"Type mismatch: Left key '{L}' {left_types} will never match right keys {right_types}"
-            raise TypeError(e)
-
     if not isinstance(left_columns, list) or not left_columns:
         raise TypeError("left_columns (list of strings) are required")
     if any(column not in T.columns for column in left_columns):

tests/test_api_basics.py

@@ -618,7 +618,7 @@ def test05_verify_show_table():
     expected = """\
 +===+=====+=====+=====+
 | # |  A  |  B  |  C  |
-|row|mixed|mixed|mixed|
+|row|empty|empty|empty|
 +---+-----+-----+-----+
 +===+=====+=====+=====+"""
     assert txt2 == expected

tests/test_join.py

@@ -561,3 +561,21 @@ def test_small_page_size():
     Config.PAGE_SIZE = original_page_size
 
 
+def test_join_with_no_pages():
+    A = Table({'A':[1,2,3], 'B':[]})
+    A.show(dtype=True, blanks="")
+
+    B = Table({'A':[1,2,3], 'B':[None,None,None]})
+    B.show(dtype=True)
+
+    C = Table({'A1': [1]})
+    A1 = C.join(A, left_keys=['A1'], right_keys=['B'])
+    assert isinstance(A1, Table), "although nothing will match, the operation is still valid"
+    B1 = C.join(B, left_keys=['A1'], right_keys=['B'])
+    assert isinstance(B1, Table), "although nothing will match, the operation is still valid"
+
+    AA = Table({'A':[1,2,3], 'B':[10,20,30]})
+    BB = Table({'A1': [1,2,3], 'B1': [1,2,3]})
+    CC = AA.join(BB, ['B'], ['B1'])
+    assert isinstance(CC, Table), "although nothing will match, the operation is still valid"
+    CC.show(dtype=True, blanks='')