Neo4j中的性能批量更新关系属性缓慢

我正在努力有效地批量更新Neo4j中的关系属性。目标是更新约500000个关系(每个关系大约有3个属性),我将其分为1000个批次,并在单个密码语句中进行处理,

UNWIND {rows} AS row
MATCH (s:Entity) WHERE s.uuid = row.source
MATCH (t:Entity) WHERE t.uuid = row.target
MATCH (s)-[r:CONSUMED]->(t)
SET r += row.properties

然而,每批1000个节点大约需要60秒。的UUID属性上存在索引 :Entity

CREATE INDEX ON :Entity(uuid)

这意味着根据查询计划匹配关系是超高效的,

总共有6个数据库命中,查询在大约150毫秒内执行。我还在UUID属性上添加了唯一性约束,确保每个匹配只返回一个元素,

CREATE CONSTRAINT ON (n:Entity) ASSERT n.uuid IS UNIQUE

有人知道我如何进一步调试它,以理解为什么Neo4j花了这么长时间来处理关系吗?

作为参考,我使用了Neo4j 3.0.3、py2neo和Bolt。Python代码块的形式为,

for chunk in chunker(relationships): # 1,000 relationships per chunk
    with graph.begin() as tx:
        statement = """
            UNWIND {rows} AS row
            MATCH (s:Entity) WHERE s.uuid = row.source
            MATCH (t:Entity) WHERE t.uuid = row.target
            MATCH (s)-[r:CONSUMED]->(t)
            SET r += row.properties
            """

            rows = []

            for rel in chunk:
                rows.append({
                    'properties': dict(rel),
                    'source': rel.start_node()['uuid'],
                    'target': rel.end_node()['uuid'],
                })

            tx.run(statement, rows=rows)