fix(graph): soft-delete graph relationships instead of hard DELETE#4188
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kartik-mem0 merged 4 commits intomem0ai:mainfrom Mar 21, 2026
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Replace hard DELETE in _delete_entities with SET r.valid = false to enable temporal reasoning over historical graph state, aligning the implementation with the paper's described architecture (arXiv:2504.19413). - _delete_entities: SET r.valid = false, r.invalidated_at = datetime() - _search_graph_db: filter WHERE r.valid IS NULL OR r.valid = true - get_all: same filter for consistency - delete_all: unchanged (explicit user action keeps DETACH DELETE) The IS NULL check ensures backward compatibility with existing edges that lack the valid property. Note: For large graphs with frequent updates, consider adding a Neo4j index on the valid property for relationship types that are frequently queried: CREATE INDEX rel_valid FOR ()-[r:RELATIONSHIP]-() ON (r.valid) Fixes mem0ai#4187 Signed-off-by: sxu75374 <imshuaixu@gmail.com>
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…em0ai#4188) Signed-off-by: sxu75374 <imshuaixu@gmail.com> Co-authored-by: kartik-mem0 <kartik.labhshetwar@mem0.ai>
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What this PR does
Replaces hard
DELETE rin graph memory's conflict resolution with soft-delete (SET r.valid = false), aligning the implementation with the architecture described in the Mem0 paper (arXiv:2504.19413).Fixes #4187
Changes
graph_memory.py:_delete_entitiesnow usesSET r.valid = falseinstead ofDELETE rgraph_memory.py: Search andget_allqueries filter onWHERE r.valid IS NULL OR r.valid = true— backward compatible with existing edges that don't have thevalidpropertytest_graph_memory_soft_delete.py: 8 tests covering Cypher generation, search filters, get_all filters, backward compat, and idempotencyWhy
The current hard
DELETEpermanently removes graph edges, making temporal reasoning impossible. When importing historical data, conflict detection can corrupt current state by deleting newer edges and replacing them with older information.Soft-delete preserves edge history and enables future temporal queries via
include_historicalparameter.Backward Compatibility
Uses
r.valid IS NULL OR r.valid = trueso existing edges without thevalidproperty continue to appear in queries. No migration needed.Signed-off-by: sxu75374 imshuaixu@gmail.com