From 37873630050f332c95bf0506aa02d47712fb454b Mon Sep 17 00:00:00 2001 From: tengqm Date: Mon, 22 Aug 2016 02:06:28 -0400 Subject: Fix marker checking when value is None There are cases where users sort a table using compound-values sort_key and one of the key has nullable set to True. For example, sorting a table using ['id', 'updated_at'] where 'updated_at' can be None. When marker_value is None, we cannot do value comparison using '<' or '>' operators. This patch adds a check if the value from the marker corresponding to the nullable-key has None value. If that is the case, we skip the comparison. Back to the example above, instead of always getting the following criteria (which doesn't work): (id > MARKER_ID) or (id == MARKER_ID && updated_at > None) <-- failure we will get the following criteria when 'updated_at' is None: (id > MARKER_ID) This is not hurting in any way to existing / legal use cases where callers are expected to include a unique key in sort keys. If there are such cases, this patch is not making things worse because the sorting is already unpredictable. Closes-Bug: #1615938 Change-Id: Iea2cd0bb2556b0b15a0baaa76ef522a3097f9928 (cherry picked from commit b3869d04cff7071c1226758eb8b58fde9eba5b8d) --- oslo_db/sqlalchemy/utils.py | 33 ++++++++++++++++++++------------- oslo_db/tests/sqlalchemy/test_utils.py | 33 ++++++++++++++++++++++++++++++++- 2 files changed, 52 insertions(+), 14 deletions(-) diff --git a/oslo_db/sqlalchemy/utils.py b/oslo_db/sqlalchemy/utils.py index c5030a0..e628908 100644 --- a/oslo_db/sqlalchemy/utils.py +++ b/oslo_db/sqlalchemy/utils.py @@ -146,7 +146,8 @@ def paginate_query(query, model, limit, sort_keys, marker=None, the lexicographical ordering: (k1 > X1) or (k1 == X1 && k2 > X2) or (k1 == X1 && k2 == X2 && k3 > X3) - We also have to cope with different sort_directions. + We also have to cope with different sort_directions and cases where k2, + k3, ... are nullable. Typically, the id of the last row is used as the client-facing pagination marker, then the actual marker object must be fetched from the db and @@ -223,18 +224,24 @@ def paginate_query(query, model, limit, sort_keys, marker=None, criteria_list = [] for i in range(len(sort_keys)): crit_attrs = [] - for j in range(i): - model_attr = getattr(model, sort_keys[j]) - crit_attrs.append((model_attr == marker_values[j])) - - model_attr = getattr(model, sort_keys[i]) - if sort_dirs[i].startswith('desc'): - crit_attrs.append((model_attr < marker_values[i])) - else: - crit_attrs.append((model_attr > marker_values[i])) - - criteria = sqlalchemy.sql.and_(*crit_attrs) - criteria_list.append(criteria) + # NOTE: We skip the marker value comparison if marker_values[i] is + # None, for two reasons: 1) the comparison operators below + # ('<', '>') are not applicable on None value; 2) this is + # safe because we can assume the primary key is included in + # sort_key, thus checked as (one of) marker values. + if marker_values[i] is not None: + for j in range(i): + model_attr = getattr(model, sort_keys[j]) + crit_attrs.append((model_attr == marker_values[j])) + + model_attr = getattr(model, sort_keys[i]) + if sort_dirs[i].startswith('desc'): + crit_attrs.append((model_attr < marker_values[i])) + else: + crit_attrs.append((model_attr > marker_values[i])) + + criteria = sqlalchemy.sql.and_(*crit_attrs) + criteria_list.append(criteria) f = sqlalchemy.sql.or_(*criteria_list) query = query.filter(f) diff --git a/oslo_db/tests/sqlalchemy/test_utils.py b/oslo_db/tests/sqlalchemy/test_utils.py index 31686fe..fc7eb03 100644 --- a/oslo_db/tests/sqlalchemy/test_utils.py +++ b/oslo_db/tests/sqlalchemy/test_utils.py @@ -77,6 +77,7 @@ class FakeTable(Base): user_id = Column(String(50), primary_key=True) project_id = Column(String(50)) snapshot_id = Column(String(50)) + updated_at = Column(DateTime, nullable=True) # mox is comparing in some awkward way that # in this case requires the same identity of object @@ -171,7 +172,8 @@ class TestPaginateQuery(test_base.BaseTestCase): self.mox.StubOutWithMock(sqlalchemy, 'desc') self.marker = FakeTable(user_id='user', project_id='p', - snapshot_id='s') + snapshot_id='s', + updated_at=None) self.model = FakeTable def test_paginate_query_no_pagination_no_sort_dirs(self): @@ -301,6 +303,35 @@ class TestPaginateQuery(test_base.BaseTestCase): marker=self.marker, sort_dirs=['asc-nullslast', 'desc-nullsfirst']) + def test_paginate_query_marker_null(self): + self.mox.StubOutWithMock(self.model.user_id, 'isnot') + self.model.user_id.isnot(None).AndReturn('asc_null_1') + sqlalchemy.desc('asc_null_1').AndReturn('asc_null_2') + self.query.order_by('asc_null_2').AndReturn(self.query) + + sqlalchemy.asc(self.model.user_id).AndReturn('asc_1') + self.query.order_by('asc_1').AndReturn(self.query) + + self.mox.StubOutWithMock(self.model.updated_at, 'is_') + self.model.updated_at.is_(None).AndReturn('desc_null_1') + sqlalchemy.desc('desc_null_1').AndReturn('desc_null_2') + self.query.order_by('desc_null_2').AndReturn(self.query) + + sqlalchemy.desc(self.model.updated_at).AndReturn('desc_1') + self.query.order_by('desc_1').AndReturn(self.query) + + self.mox.StubOutWithMock(sqlalchemy.sql, 'and_') + sqlalchemy.sql.and_(mock.ANY).AndReturn('some_crit') + self.mox.StubOutWithMock(sqlalchemy.sql, 'or_') + sqlalchemy.sql.or_('some_crit').AndReturn('some_f') + self.query.filter('some_f').AndReturn(self.query) + self.query.limit(5).AndReturn(self.query) + self.mox.ReplayAll() + utils.paginate_query(self.query, self.model, 5, + ['user_id', 'updated_at'], + marker=self.marker, + sort_dirs=['asc-nullslast', 'desc-nullsfirst']) + def test_paginate_query_value_error(self): sqlalchemy.asc(self.model.user_id).AndReturn('asc_1') self.query.order_by('asc_1').AndReturn(self.query) -- cgit v1.2.1