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fix(graph): soft-delete graph relationships instead of hard DELETE (#4188)

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Signed-off-by: sxu75374 <imshuaixu@gmail.com>
Co-authored-by: kartik-mem0 <kartik.labhshetwar@mem0.ai>
This commit is contained in:
darrenxu
2026-03-21 05:02:59 -07:00
committed by GitHub
parent 824032a81d
commit 884e740b53
2 changed files with 361 additions and 18 deletions
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mem0/memory/graph_memory.py
+43 -15
View File
@@ -174,6 +174,7 @@ class MemoryGraph:
query = f"""
MATCH (n {self.node_label} {{{node_props_str}}})-[r]->(m {self.node_label} {{{node_props_str}}})
WHERE r.valid IS NULL OR r.valid = true
RETURN n.name AS source, type(r) AS relationship, m.name AS target
LIMIT $limit
"""
@@ -291,10 +292,12 @@ class MemoryGraph:
CALL {{
WITH n
MATCH (n)-[r]->(m {self.node_label} {{{node_props_str}}})
WHERE r.valid IS NULL OR r.valid = true
RETURN n.name AS source, elementId(n) AS source_id, type(r) AS relationship, elementId(r) AS relation_id, m.name AS destination, elementId(m) AS destination_id
UNION
WITH n
MATCH (n)<-[r]-(m {self.node_label} {{{node_props_str}}})
WHERE r.valid IS NULL OR r.valid = true
RETURN m.name AS source, elementId(m) AS source_id, type(r) AS relationship, elementId(r) AS relation_id, n.name AS destination, elementId(n) AS destination_id
}}
WITH distinct source, source_id, relationship, relation_id, destination, destination_id, similarity
@@ -392,13 +395,15 @@ class MemoryGraph:
source_props_str = ", ".join(source_props)
dest_props_str = ", ".join(dest_props)
# Delete the specific relationship between nodes
# Soft-delete: mark relationship as invalid instead of removing it,
# enabling temporal reasoning over historical graph state.
# See: https://github.com/mem0ai/mem0/issues/4187
cypher = f"""
MATCH (n {self.node_label} {{{source_props_str}}})
-[r:{relationship}]->
(m {self.node_label} {{{dest_props_str}}})
DELETE r
WHERE r.valid IS NULL OR r.valid = true
SET r.valid = false, r.invalidated_at = datetime()
RETURN
n.name AS source,
m.name AS target,
@@ -465,10 +470,15 @@ class MemoryGraph:
WITH source, destination
MERGE (source)-[r:{relationship}]->(destination)
ON CREATE SET
r.created = timestamp(),
r.mentions = 1
r.created_at = timestamp(),
r.updated_at = timestamp(),
r.mentions = 1,
r.valid = true
ON MATCH SET
r.mentions = coalesce(r.mentions, 0) + 1
r.mentions = coalesce(r.mentions, 0) + 1,
r.valid = true,
r.updated_at = timestamp(),
r.invalidated_at = null
RETURN source.name AS source, type(r) AS relationship, destination.name AS target
"""
@@ -509,10 +519,15 @@ class MemoryGraph:
WITH source, destination
MERGE (source)-[r:{relationship}]->(destination)
ON CREATE SET
r.created = timestamp(),
r.mentions = 1
r.created_at = timestamp(),
r.updated_at = timestamp(),
r.mentions = 1,
r.valid = true
ON MATCH SET
r.mentions = coalesce(r.mentions, 0) + 1
r.mentions = coalesce(r.mentions, 0) + 1,
r.valid = true,
r.updated_at = timestamp(),
r.invalidated_at = null
RETURN source.name AS source, type(r) AS relationship, destination.name AS target
"""
@@ -540,8 +555,13 @@ class MemoryGraph:
ON CREATE SET
r.created_at = timestamp(),
r.updated_at = timestamp(),
r.mentions = 1
ON MATCH SET r.mentions = coalesce(r.mentions, 0) + 1
r.mentions = 1,
r.valid = true
ON MATCH SET
r.mentions = coalesce(r.mentions, 0) + 1,
r.valid = true,
r.updated_at = timestamp(),
r.invalidated_at = null
RETURN source.name AS source, type(r) AS relationship, destination.name AS target
"""
@@ -585,10 +605,18 @@ class MemoryGraph:
WITH source, destination
CALL db.create.setNodeVectorProperty(destination, 'embedding', $dest_embedding)
WITH source, destination
MERGE (source)-[rel:{relationship}]->(destination)
ON CREATE SET rel.created = timestamp(), rel.mentions = 1
ON MATCH SET rel.mentions = coalesce(rel.mentions, 0) + 1
RETURN source.name AS source, type(rel) AS relationship, destination.name AS target
MERGE (source)-[r:{relationship}]->(destination)
ON CREATE SET
r.created_at = timestamp(),
r.updated_at = timestamp(),
r.mentions = 1,
r.valid = true
ON MATCH SET
r.mentions = coalesce(r.mentions, 0) + 1,
r.valid = true,
r.updated_at = timestamp(),
r.invalidated_at = null
RETURN source.name AS source, type(r) AS relationship, destination.name AS target
"""
params = {
tests/memory/test_graph_memory_soft_delete.py
+315
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@@ -0,0 +1,315 @@
"""Tests for graph memory soft-delete behavior.
Verifies that _delete_entities marks relationships as invalid (soft-delete)
rather than permanently removing them, and that search/retrieval queries
exclude soft-deleted relationships by default.
See: https://github.com/mem0ai/mem0/issues/4187
"""
from unittest.mock import Mock, patch
# Mock optional deps at module level so the import works across all Python
# versions without triggering transitive C-extension reloads (numpy via
# qdrant_client). This matches the pattern in test_memgraph_memory.py.
_neo4j_mock = Mock()
patch.dict("sys.modules", {
"langchain_neo4j": _neo4j_mock,
"rank_bm25": Mock(),
}).start()
from mem0.memory.graph_memory import MemoryGraph # noqa: E402
def _create_graph_memory():
"""Create a MemoryGraph instance with mocked dependencies."""
with patch.object(MemoryGraph, "__init__", lambda self, *a, **kw: None):
mg = MemoryGraph.__new__(MemoryGraph)
mg.graph = Mock()
mg.graph.query = Mock(return_value=[])
mg.embedding_model = Mock()
mg.embedding_model.embed = Mock(return_value=[0.1] * 128)
mg.llm = Mock()
mg.node_label = ":Entity"
mg.threshold = 0.7
mg.llm_provider = "openai"
return mg
class TestSoftDelete:
"""Verify _delete_entities uses SET r.valid = false, not DELETE r."""
def test_delete_entities_sends_soft_delete_cypher(self):
mg = _create_graph_memory()
mg.graph.query.return_value = [
{"source": "Alice", "target": "Bob", "relationship": "KNOWS"}
]
mg._delete_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1"},
)
cypher = mg.graph.query.call_args[0][0]
assert "SET r.valid = false" in cypher
assert "r.invalidated_at = datetime()" in cypher
assert "DELETE r" not in cypher
def test_delete_entities_only_targets_valid_edges(self):
mg = _create_graph_memory()
mg._delete_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1"},
)
cypher = mg.graph.query.call_args[0][0]
assert "r.valid IS NULL OR r.valid = true" in cypher
def test_delete_entities_is_idempotent(self):
mg = _create_graph_memory()
item = [{"source": "alice", "destination": "bob", "relationship": "KNOWS"}]
filters = {"user_id": "user1"}
mg.graph.query.return_value = [
{"source": "Alice", "target": "Bob", "relationship": "KNOWS"}
]
mg._delete_entities(item, filters)
mg.graph.query.return_value = []
mg._delete_entities(item, filters)
# Both calls should have the same WHERE filter
for c in mg.graph.query.call_args_list:
assert "r.valid IS NULL OR r.valid = true" in c[0][0]
class TestSearchExcludesSoftDeleted:
"""Verify search and get_all filter out soft-deleted relationships."""
def test_get_all_filters_soft_deleted(self):
mg = _create_graph_memory()
mg.get_all(filters={"user_id": "user1"}, limit=10)
cypher = mg.graph.query.call_args[0][0]
assert "r.valid IS NULL OR r.valid = true" in cypher
def test_search_graph_db_filters_both_directions(self):
"""_search_graph_db must filter soft-deleted edges in both outgoing and incoming queries."""
mg = _create_graph_memory()
mg.graph.query.return_value = []
mg._search_graph_db(node_list=["alice"], filters={"user_id": "user1"})
cypher = mg.graph.query.call_args[0][0]
# The UNION query has two MATCH branches — both must filter
occurrences = cypher.count("r.valid IS NULL OR r.valid = true")
assert occurrences >= 2, (
f"_search_graph_db has {occurrences} valid-filter(s) but needs >= 2 "
"(one for outgoing, one for incoming relationships)"
)
def test_delete_all_still_hard_deletes(self):
mg = _create_graph_memory()
mg.delete_all(filters={"user_id": "user1"})
cypher = mg.graph.query.call_args[0][0]
assert "DETACH DELETE" in cypher
class TestMergeResetsValidFlag:
"""Verify MERGE in _add_entities sets r.valid = true.
Critical: after soft-delete, a MERGE that matches the existing
(invalidated) edge must reset valid=true, or the edge becomes
a zombie -- exists but invisible to queries.
"""
def _run_add_entities(self, source_found, dest_found):
"""Helper: call _add_entities with configurable node search results."""
mg = _create_graph_memory()
source_result = (
[{"elementId(source_candidate)": "src_id_1"}] if source_found else []
)
dest_result = (
[{"elementId(destination_candidate)": "dst_id_1"}] if dest_found else []
)
mg._search_source_node = Mock(return_value=source_result)
mg._search_destination_node = Mock(return_value=dest_result)
mg._add_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1"},
entity_type_map={},
)
cypher = mg.graph.query.call_args[0][0]
return cypher
def test_merge_sets_valid_true_when_source_found(self):
cypher = self._run_add_entities(source_found=True, dest_found=False)
assert "r.valid = true" in cypher
def test_merge_sets_valid_true_when_dest_found(self):
cypher = self._run_add_entities(source_found=False, dest_found=True)
assert "r.valid = true" in cypher
def test_merge_sets_valid_true_when_both_found(self):
cypher = self._run_add_entities(source_found=True, dest_found=True)
assert "r.valid = true" in cypher
def test_merge_sets_valid_true_when_neither_found(self):
cypher = self._run_add_entities(source_found=False, dest_found=False)
assert "r.valid = true" in cypher
def test_merge_clears_invalidated_at_on_resurrection(self):
"""When a soft-deleted edge is resurrected via MERGE, invalidated_at must be cleared.
Without this, a resurrected edge (valid=true) still carries stale
invalidated_at metadata, which corrupts temporal reasoning queries.
"""
for label, src, dst in [
("source found", True, False),
("dest found", False, True),
("both found", True, True),
("neither found", False, False),
]:
cypher = self._run_add_entities(source_found=src, dest_found=dst)
assert "r.invalidated_at = null" in cypher, (
f"MERGE path '{label}': ON MATCH SET does not clear r.invalidated_at. "
"Resurrected edges will have stale invalidation timestamps."
)
class TestCypherConsistency:
"""Verify all MERGE blocks use consistent property names and variable aliases."""
def _get_merge_cypher(self, source_found, dest_found):
mg = _create_graph_memory()
mg._search_source_node = Mock(
return_value=[{"elementId(source_candidate)": "id1"}] if source_found else []
)
mg._search_destination_node = Mock(
return_value=[{"elementId(destination_candidate)": "id2"}] if dest_found else []
)
mg._add_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1"},
entity_type_map={},
)
return mg.graph.query.call_args[0][0]
def test_all_blocks_use_created_at_not_created(self):
"""All MERGE blocks must use r.created_at, not r.created."""
for label, src, dst in [
("source found", True, False),
("dest found", False, True),
("both found", True, True),
("neither found", False, False),
]:
cypher = self._get_merge_cypher(src, dst)
assert "r.created_at" in cypher, (
f"MERGE path '{label}': uses r.created instead of r.created_at"
)
def test_all_blocks_use_r_not_rel(self):
"""All MERGE blocks must use 'r' as the relationship variable, not 'rel'."""
for label, src, dst in [
("source found", True, False),
("dest found", False, True),
("both found", True, True),
("neither found", False, False),
]:
cypher = self._get_merge_cypher(src, dst)
assert "rel." not in cypher, (
f"MERGE path '{label}': uses 'rel' variable instead of 'r'"
)
def test_all_blocks_set_updated_at_on_create(self):
"""All MERGE blocks must set r.updated_at on CREATE for consistent timestamps."""
for label, src, dst in [
("source found", True, False),
("dest found", False, True),
("both found", True, True),
("neither found", False, False),
]:
cypher = self._get_merge_cypher(src, dst)
assert "r.updated_at = timestamp()" in cypher, (
f"MERGE path '{label}': missing r.updated_at on CREATE SET"
)
class TestSoftDeleteWithFilters:
"""Verify soft-delete works correctly with agent_id and run_id filters."""
def test_delete_entities_with_agent_id(self):
mg = _create_graph_memory()
mg._delete_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1", "agent_id": "agent1"},
)
cypher = mg.graph.query.call_args[0][0]
params = mg.graph.query.call_args[1]["params"]
assert "SET r.valid = false" in cypher
assert "agent_id: $agent_id" in cypher
assert params["agent_id"] == "agent1"
def test_delete_entities_with_run_id(self):
mg = _create_graph_memory()
mg._delete_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1", "run_id": "run1"},
)
cypher = mg.graph.query.call_args[0][0]
params = mg.graph.query.call_args[1]["params"]
assert "SET r.valid = false" in cypher
assert "run_id: $run_id" in cypher
assert params["run_id"] == "run1"
def test_get_all_with_agent_id_filters_soft_deleted(self):
mg = _create_graph_memory()
mg.get_all(filters={"user_id": "user1", "agent_id": "agent1"}, limit=10)
cypher = mg.graph.query.call_args[0][0]
assert "r.valid IS NULL OR r.valid = true" in cypher
assert "agent_id: $agent_id" in cypher
def test_merge_with_agent_id_sets_valid_true(self):
mg = _create_graph_memory()
mg._search_source_node = Mock(
return_value=[{"elementId(source_candidate)": "id1"}]
)
mg._search_destination_node = Mock(return_value=[])
mg._add_entities(
[{"source": "alice", "destination": "bob", "relationship": "KNOWS"}],
{"user_id": "user1", "agent_id": "agent1"},
entity_type_map={},
)
cypher = mg.graph.query.call_args[0][0]
assert "r.valid = true" in cypher
assert "agent_id: $agent_id" in cypher
class TestResetAndCleanup:
"""Verify reset and delete_all use hard-delete (DETACH DELETE)."""
def test_reset_uses_detach_delete(self):
mg = _create_graph_memory()
mg.reset()
cypher = mg.graph.query.call_args[0][0]
assert "DETACH DELETE" in cypher
assert "valid" not in cypher.lower()
def test_delete_all_does_not_soft_delete(self):
mg = _create_graph_memory()
mg.delete_all(filters={"user_id": "user1"})
cypher = mg.graph.query.call_args[0][0]
assert "DETACH DELETE" in cypher
assert "r.valid = false" not in cypher