- calling expr.in_([]), i.e. with an empty list, emits a warning

before issuing the usual "expr != expr" clause.  The
"expr != expr" can be very expensive, and it's preferred
that the user not issue in_() if the list is empty,
instead simply not querying, or modifying the criterion
as appropriate for more complex situations.
[ticket:1628]

2 files changed, 4 insertions, 0 deletions

diff --git a/test/sql/test_query.py b/test/sql/test_query.py
index 0e1787e9e..c711819f9 100644
--- a/test/sql/test_query.py
+++ b/test/sql/test_query.py
@@ -721,6 +721,7 @@ class QueryTest(TestBase):
         finally:
             shadowed.drop(checkfirst=True)
 
+    @testing.emits_warning('.*empty sequence.*')
     def test_in_filtering(self):
         """test the behavior of the in_() function."""
 
@@ -747,6 +748,7 @@ class QueryTest(TestBase):
         # Null values are not outside any set
         assert len(r) == 0
 
+    @testing.emits_warning('.*empty sequence.*')
     @testing.fails_on('firebird', "kinterbasdb doesn't send full type information")
     def test_bind_in(self):
         users.insert().execute(user_id = 7, user_name = 'jack')
@@ -761,6 +763,7 @@ class QueryTest(TestBase):
         r = s.execute(search_key=None).fetchall()
         assert len(r) == 0
 
+    @testing.emits_warning('.*empty sequence.*')
     @testing.fails_on('firebird', 'FIXME: unknown')
     @testing.fails_on('maxdb', 'FIXME: unknown')
     @testing.fails_on('oracle', 'FIXME: unknown')
diff --git a/test/sql/test_select.py b/test/sql/test_select.py
index 42998ee02..d063bd2d9 100644
--- a/test/sql/test_select.py
+++ b/test/sql/test_select.py
@@ -1265,6 +1265,7 @@ UNION SELECT mytable.myid FROM mytable"
         
         assert [str(c) for c in s.c] == ["id", "hoho"]
 
+    @testing.emits_warning('.*empty sequence.*')
     def test_in(self):
         self.assert_compile(select([table1], table1.c.myid.in_(['a'])),
         "SELECT mytable.myid, mytable.name, mytable.description FROM mytable WHERE mytable.myid IN (:myid_1)")