fix(ir): ensure that schema column order matters

ibis/backends/tests/test_client.py

@@ -1608,3 +1608,14 @@ def test_json_to_pyarrow(con):
         if val is not None
     }
     assert result == expected
+
+
+def test_schema_with_caching(alltypes):
+    t1 = alltypes.limit(5).select("int_col", "string_col")
+    t2 = alltypes.limit(5).select("string_col", "int_col")
+
+    pt1 = t1.cache()
+    pt2 = t2.cache()
+
+    assert pt1.schema() == ibis.schema(dict(int_col="int32", string_col="string"))
+    assert pt2.schema() == ibis.schema(dict(string_col="string", int_col="int32"))

ibis/common/collections.py

@@ -287,6 +287,11 @@ def __init__(self, *args, **kwargs):
     def __hash__(self) -> int:
         return self.__precomputed_hash__
 
+    def __eq__(self, other: Any) -> bool:
+        if not isinstance(other, collections.abc.Mapping):
+            return NotImplemented
+        return collections.OrderedDict(self) == collections.OrderedDict(other)
+
     def __setitem__(self, key: K, value: V) -> None:
         raise TypeError("'FrozenDict' object does not support item assignment")
 

ibis/expr/schema.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import collections
 from collections.abc import Iterable, Iterator, Mapping
 from typing import TYPE_CHECKING, Any, Union
 
@@ -90,6 +91,14 @@ def equals(self, other: Schema) -> bool:
             )
         return self == other
 
+    def __hash__(self) -> int:
+        return super().__hash__()
+
+    def __eq__(self, other):
+        if not isinstance(other, Mapping):
+            return NotImplemented
+        return collections.OrderedDict(self) == collections.OrderedDict(other)
+
     @classmethod
     def from_tuples(
         cls,

ibis/expr/tests/test_dereference.py

@@ -24,8 +24,8 @@ def test_dereference_project():
     expected = dereference_expect(
         {
             p.int_col: p.int_col,
-            p.double_col: p.double_col,
             t.int_col: p.int_col,
+            p.double_col: p.double_col,
             t.double_col: p.double_col,
         }
     )