UPDATE EDGE with compare-and-swap (CAS).

[newcworld]

General Question

I notice that https://docs.nebula-graph.io/3.2.0/3.ngql-guide/13.edge-statements/2.update-edge/ say that

In Nebula Graph, UPDATE EDGE supports compare-and-swap (CAS).

But I cannot find any extra info about this, How can I update a edge with CAS

[wey-gu]

General Question

I notice that https://docs.nebula-graph.io/3.2.0/3.ngql-guide/13.edge-statements/2.update-edge/ say that

In Nebula Graph, UPDATE EDGE supports compare-and-swap (CAS).

But I cannot find any extra info about this, How can I update a edge with CAS

By adding when clause in update:
WHEN <condition>.

[newcworld]

But when I use this like

UPDATE EDGE ON like "n:1:1:1" -> "n:1:1:2"
SET modify_time = timestamp(), version = version + 1
WHEN version == 1

When the version has been changed by other thread. such as it become 2.
it will not return any response about whether this update is succeed

[newcworld]

I find that I can do this

UPDATE EDGE ON like "n:1:1:1" -> "n:1:1:2"
SET modify_time = timestamp(), version = version + 1
WHEN version == 1
YIELD version

[wey-gu]

I find that I can do this

UPDATE EDGE ON like "n:1:1:1" -> "n:1:1:2"
SET modify_time = timestamp(), version = version + 1
WHEN version == 1
YIELD version

Sorry for not checking your follow-up questions on time, yes, we could yield any fields and yield version will do the job 👍🏻