fix(sql)!: simplify_query no longer strips table names

This functionality both produced queries that were invalid, and involved
futzing with the sqlalchemy compiler, which appeared to break for
certain sqlalchemy versions.

siuba/dply/verbs.py

@@ -2447,11 +2447,14 @@ def tbl(src, *args, **kwargs):
     You can analyze a mock table
 
     >>> from sqlalchemy import create_mock_engine
+    >>> from siuba import _
+
     >>> mock_engine = create_mock_engine("postgresql:///", lambda *args, **kwargs: None)
     >>> tbl_mock = tbl(mock_engine, "some_table", columns = ["a", "b", "c"])
+
     >>> q = tbl_mock >> count(_.a) >> show_query()    # doctest: +NORMALIZE_WHITESPACE
-    SELECT a, count(*) AS n
-    FROM some_table AS some_table_1 GROUP BY a ORDER BY n DESC
+    SELECT some_table_1.a, count(*) AS n
+    FROM some_table AS some_table_1 GROUP BY some_table_1.a ORDER BY n DESC
     """
 
     return src

siuba/sql/utils.py

@@ -190,21 +190,3 @@ def simplify_sel(sel):
 
     return clone_el
 
-
-@contextmanager
-def _use_simple_names():
-    from sqlalchemy import sql
-    from sqlalchemy.ext.compiler import compiles, deregister
-
-    get_col_name = lambda el, *args, **kwargs: str(el.element.name)
-    get_lab_name = lambda el, *args, **kwargs: str(el.element.name)
-    get_col_name = lambda el, *args, **kwargs: str(el.name)
-    compiles(sql.compiler._CompileLabel)(get_lab_name)
-    compiles(sql.elements.ColumnClause)(get_col_name)
-    compiles(sql.schema.Column)(get_col_name)
-    try:
-        yield 1
-    except:
-        pass
-    finally:
-        deregister(sql.compiler._CompileLabel)

siuba/sql/verbs.py

@@ -42,7 +42,6 @@
     _sql_add_columns,
     _sql_with_only_columns,
     _sql_simplify_select,
-    _use_simple_names,
     MockConnection
 )
 
@@ -465,8 +464,7 @@ def _show_query(tbl, simplify = False, return_table = True):
         # try to strip table names and labels where unnecessary
         simple_sel = _sql_simplify_select(tbl.last_select)
 
-        with _use_simple_names():
-            explained = compile_query(simple_sel)
+        explained = compile_query(simple_sel)
     else:
         # use a much more verbose query
         explained = compile_query(tbl.last_select)

siuba/tests/test_verb_show_query.py

@@ -32,15 +32,15 @@ def test_show_query_basic_simplify(df_tiny):
     q = df_tiny >> mutate(a = _.x.mean()) >> show_query(return_table = False, simplify=True)
 
     assert rename_source(str(q), df_tiny) == """\
-SELECT *, avg(x) OVER () AS a 
+SELECT *, avg(SRC_TBL.x) OVER () AS a 
 FROM SRC_TBL"""
 
 def test_show_query_complex_simplify(df_wide):
     q = df_wide >>  mutate(a = _.x.mean(), b = _.a.mean())
     res = q >> show_query(return_table = False, simplify=True)
 
     assert rename_source(str(res), df_wide) == """\
-SELECT *, avg(a) OVER () AS b 
-FROM (SELECT *, avg(x) OVER () AS a 
+SELECT *, avg(anon_1.a) OVER () AS b 
+FROM (SELECT *, avg(SRC_TBL.x) OVER () AS a 
 FROM SRC_TBL) AS anon_1"""