FAQ: $^,$$ value reversed

[cjdxhjj]

Please check the FAQ documentation before raising an issue

Describe the bug (required)

Your Environments (required)

• OS: uname -a
• Compiler: g++ --version or clang++ --version
• CPU: lscpu
• Commit id (e.g. a3ffc7d8)

How To Reproduce(required)

Steps to reproduce the behavior:

the edge begin from col:2615 to metric:f1ee2e6076724c8a9af40680d67ca549, but the id($^) return metric:f1ee2e6076724c8a9af40680d67ca549 and id($$) return col:2615

Expected behavior

Additional context

[cjdxhjj]

what the source and target mean?

[cjdxhjj]

the src(edge), and dst(edge) return correct

[QingZ11]

"src" and "dst" represent the starting point and the ending point of an edge, respectively, while $^ and $$ are reference symbols in the NebulaGraph query language nGQL, used to refer to the starting and ending points.

BTW, the term BIDIRECT represents a bidirectional edge, which will return the edge from 'a' to 'b' as well as the edge from 'b' to 'a'.

In this example, there may only exist a reverse edge, which is why the source and destination in the results are reversed.

[wey-gu]

Great catch!

You are seeing the nature difference between $$ and dst.

Each edge was persisted twice, one together with its starting vertex and one with the ending vertex(the inverse edge), and dst ensured the expected direction of this behavior.

You could add this typeid(edge) to better understand it, when typeid is negative, you are getting the edge that's the inverse edge.

go from "player100" over * bidirect yield dst(edge), src(edge), id($$), id($^), typeid(edge)
+-------------+-------------+-------------+-------------+--------------+
| dst(EDGE)   | src(EDGE)   | id($$)      | id($^)      | typeid(EDGE) |
+-------------+-------------+-------------+-------------+--------------+
| "player100" | "player101" | "player101" | "player100" | -5           |
| "player100" | "player102" | "player102" | "player100" | -5           |
| "player100" | "player104" | "player104" | "player100" | -5           |
| "player100" | "player105" | "player105" | "player100" | -5           |
| "player100" | "player107" | "player107" | "player100" | -5           |
| "player100" | "player108" | "player108" | "player100" | -5           |
| "player100" | "player109" | "player109" | "player100" | -5           |
| "player100" | "player113" | "player113" | "player100" | -5           |
| "player100" | "player125" | "player125" | "player100" | -5           |
| "player100" | "player144" | "player144" | "player100" | -5           |
| "post1"     | "player100" | "post1"     | "player100" | 9            |
| "post11"    | "player100" | "post11"    | "player100" | 9            |
| "player101" | "player100" | "player101" | "player100" | 5            |
| "player125" | "player100" | "player125" | "player100" | 5            |
| "addr_4"    | "player100" | "addr_4"    | "player100" | 14           |
| "team204"   | "player100" | "team204"   | "player100" | 4            |
+-------------+-------------+-------------+-------------+--------------+
Got 16 rows (time spent 3.472ms/12.645375ms)

[cjdxhjj]

thanks for your replay, @wey-gu @QingZ11