BUG: read_hdf bad filtering in case of categorical string columns

doc/source/whatsnew/v1.3.0.rst

@@ -327,6 +327,7 @@ I/O
 - Bug in :func:`read_csv` not switching ``true_values`` and ``false_values`` for nullable ``boolean`` dtype (:issue:`34655`)
 - Bug in :func:`read_json` when ``orient="split"`` does not maintain numeric string index (:issue:`28556`)
 - :meth:`read_sql` returned an empty generator if ``chunksize`` was no-zero and the query returned no results. Now returns a generator with a single empty dataframe (:issue:`34411`)
+- Bug in :func:`read_hdf` returning unexpected records when filtering on categorical string columns using ``where`` parameter (:issue:`39189`)
 
 Period
 ^^^^^^

pandas/core/computation/pytables.py

@@ -210,12 +210,10 @@ def stringify(value):
             return TermValue(int(v), v, kind)
         elif meta == "category":
             metadata = extract_array(self.metadata, extract_numpy=True)
-            result = metadata.searchsorted(v, side="left")
-
-            # result returns 0 if v is first element or if v is not in metadata
-            # check that metadata contains v
-            if not result and v not in metadata:
+            if v not in metadata:
                 result = -1
+            else:
+                result = metadata.searchsorted(v, side="left")
             return TermValue(result, result, "integer")
         elif kind == "integer":
             v = int(float(v))