From f78621a104b7e02f3162888abf5bcb309942f334 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 19 Mar 2020 14:47:41 +0100
Subject: [PATCH 1/2] PERF: skip non-consolidatable blocks when checking
 consolidation

---
 pandas/core/internals/managers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index da334561385d6..ada065bc304ff 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -676,7 +676,7 @@ def is_consolidated(self) -> bool:
         return self._is_consolidated
 
     def _consolidate_check(self) -> None:
-        ftypes = [blk.ftype for blk in self.blocks]
+        ftypes = [blk.ftype for blk in self.blocks if blk._can_consolidate]
         self._is_consolidated = len(ftypes) == len(set(ftypes))
         self._known_consolidated = True
 

From 72c01e058cf0f27d52db5843a4ab568e59892243 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 19 Mar 2020 17:19:18 +0100
Subject: [PATCH 2/2] remove ftypes

---
 pandas/core/arrays/sparse/array.py |  1 -
 pandas/core/internals/blocks.py    | 13 -------------
 pandas/core/internals/managers.py  |  4 ++--
 3 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/pandas/core/arrays/sparse/array.py b/pandas/core/arrays/sparse/array.py
index 963c2f3d53138..8021e0babe4e0 100644
--- a/pandas/core/arrays/sparse/array.py
+++ b/pandas/core/arrays/sparse/array.py
@@ -268,7 +268,6 @@ class SparseArray(PandasObject, ExtensionArray, ExtensionOpsMixin):
     Indices: array([2, 3], dtype=int32)
     """
 
-    _pandas_ftype = "sparse"
     _subtyp = "sparse_array"  # register ABCSparseArray
     _deprecations = PandasObject._deprecations | frozenset(["get_values"])
     _sparse_index: SparseIndex
diff --git a/pandas/core/internals/blocks.py b/pandas/core/internals/blocks.py
index adeb1ae04a58d..fec8639f5a44d 100644
--- a/pandas/core/internals/blocks.py
+++ b/pandas/core/internals/blocks.py
@@ -110,7 +110,6 @@ class Block(PandasObject):
     _can_consolidate = True
     _verify_integrity = True
     _validate_ndim = True
-    _ftype = "dense"
     _concatenator = staticmethod(np.concatenate)
 
     def __init__(self, values, placement, ndim=None):
@@ -322,14 +321,6 @@ def shape(self):
     def dtype(self):
         return self.values.dtype
 
-    @property
-    def ftype(self) -> str:
-        if getattr(self.values, "_pandas_ftype", False):
-            dtype = self.dtype.subtype
-        else:
-            dtype = self.dtype
-        return f"{dtype}:{self._ftype}"
-
     def merge(self, other):
         return _merge_blocks([self, other])
 
@@ -1956,10 +1947,6 @@ def where(
 
         return [self.make_block_same_class(result, placement=self.mgr_locs)]
 
-    @property
-    def _ftype(self):
-        return getattr(self.values, "_pandas_ftype", Block._ftype)
-
     def _unstack(self, unstacker_func, new_columns, n_rows, fill_value):
         # ExtensionArray-safe unstack.
         # We override ObjectBlock._unstack, which unstacks directly on the
diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index ada065bc304ff..66e96af05eb71 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -676,8 +676,8 @@ def is_consolidated(self) -> bool:
         return self._is_consolidated
 
     def _consolidate_check(self) -> None:
-        ftypes = [blk.ftype for blk in self.blocks if blk._can_consolidate]
-        self._is_consolidated = len(ftypes) == len(set(ftypes))
+        dtypes = [blk.dtype for blk in self.blocks if blk._can_consolidate]
+        self._is_consolidated = len(dtypes) == len(set(dtypes))
         self._known_consolidated = True
 
     @property