fix(drop): ignore order for DropColumns equality

ibis/expr/operations/relations.py

@@ -148,7 +148,7 @@ def schema(self):
 @public
 class DropColumns(Relation):
     parent: Relation
-    columns_to_drop: VarTuple[str]
+    columns_to_drop: frozenset[str]
 
     @attribute
     def schema(self):

ibis/expr/types/relations.py

@@ -2501,7 +2501,7 @@ def drop(self, *fields: str | Selector) -> Table:
             # no-op if nothing to be dropped
             return self
 
-        columns_to_drop = tuple(
+        columns_to_drop = frozenset(
             map(operator.methodcaller("get_name"), self._fast_bind(*fields))
         )
         return ops.DropColumns(parent=self, columns_to_drop=columns_to_drop).to_expr()

ibis/tests/expr/test_table.py

@@ -1886,6 +1886,12 @@ def test_drop():
         t.drop("e")
 
 
+def test_drop_equality():
+    t = ibis.table(dict.fromkeys("abcd", "int"))
+
+    assert t.drop("a", "b").equals(t.drop("b", "a"))
+
+
 def test_python_table_ambiguous():
     with pytest.raises(NotImplementedError):
         ibis.memtable(