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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 17:32:59 +05:30
committed by GitHub
co-authored by kartik-mem0
parent 824032a81d
commit 884e740b53
2 changed files with 361 additions and 18 deletions
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mem0/memory/graph_memory.py
+46 -18
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@@ -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,
@@ -464,11 +469,16 @@ class MemoryGraph:
CALL db.create.setNodeVectorProperty(destination, 'embedding', $destination_embedding)
WITH source, destination
MERGE (source)-[r:{relationship}]->(destination)
ON CREATE SET
r.created = timestamp(),
r.mentions = 1
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.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
"""
@@ -508,11 +518,16 @@ class MemoryGraph:
CALL db.create.setNodeVectorProperty(source, 'embedding', $source_embedding)
WITH source, destination
MERGE (source)-[r:{relationship}]->(destination)
ON CREATE SET
r.created = timestamp(),
r.mentions = 1
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.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
"""
@@ -537,11 +552,16 @@ class MemoryGraph:
WHERE elementId(destination) = $destination_id
SET destination.mentions = coalesce(destination.mentions, 0) + 1
MERGE (source)-[r:{relationship}]->(destination)
ON CREATE SET
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 = {