nebula-graph3.0.0使用if not exists插入边时候出现数据异常

[xiaofaning]

nebula 插入一条边后，默认match-[e:relation]-(n) 查询会有两个边查询初恋，此时调用insert into edge if not exists 插入相同id指向边的时候更换边的属性字段出现两条不一样的边

[xiaofaning]

希望各位大佬们能解答一下我这个小菜鸡的问题，万分感谢！！！！！

[wey-gu]

What is your query please?

[xiaofaning]

After nebula inserts an edge, the default match-[e:relation]-(n) query will have two edge queries. In this case, when you call insert edge if not exists, when the same id is inserted into the edge, two different edges appear in the attribute field of the replacement edge

[wey-gu]

match-[e:relation]-(n) is not even a valid query

[xiaofaning]

match-[e:relation]-(n) return e

[wey-gu]

I guess you are querying something like this:

match (m)-[e:relation]-(n) return id(m), e, id(n)

Now I understand your concern!

First question, why 2 edges returned.

This is due to in NebulaGraph edges were duplicated and persisted in two parts of space, one in source, and one in destination.

(root@nebula) [basketballplayer]> MATCH (m)-[e:serve]-(n) WHERE src(e) == "player145" RETURN id(m), e, id(n)
+-------------+-----------------------------------------------------------------------+-------------+
| id(m)       | e                                                                     | id(n)       |
+-------------+-----------------------------------------------------------------------+-------------+
| "player145" | [:serve "player145"->"team228" @0 {end_year: 2012, start_year: 2008}] | "team228"   |
| "team228"   | [:serve "player145"->"team228" @0 {end_year: 2012, start_year: 2008}] | "player145" |
...
+-------------+-----------------------------------------------------------------------+-------------+
Got 10 rows (time spent 8.693ms/113.304458ms)

Thus, this is recommended(with direction)

(root@nebula) [basketballplayer]> MATCH (m)-[e:serve]->(n) WHERE src(e) == "player145" RETURN id(m), e, id(n)
+-------------+-----------------------------------------------------------------------+-----------+
| id(m)       | e                                                                     | id(n)     |
+-------------+-----------------------------------------------------------------------+-----------+
| "player145" | [:serve "player145"->"team228" @0 {end_year: 2012, start_year: 2008}] | "team228" |
...
+-------------+-----------------------------------------------------------------------+-----------+
Got 5 rows (time spent 6.493ms/110.213167ms)

Thu, 10 Aug 2023 12:36:55 CST

And further, if you would need to return id of src and dst, this one is even better:

MATCH ()-[e:serve]->() WHERE src(e) == "player145" RETURN src(e), properties(e), dst(e)

Second question, why props are different?

This was due to there is no transaction on this level, thus there is a chance the insert got corruptions, if you are on 3.0.0, you could actually switch on TOSS to add transactions on this level.

In your case(which is actually quite rare), you could try redo INSERT without the IF NOT EXISTS to override the corrupted data :).

Thanks!

[xiaofaning]

Thank you very much!