Unexpected edge direction in MATCH...WHERE... query result

[r9liucc]

Environments

• OS: macOS Monterey 12.1, MacBook Pro (16-inch, 2019)
• CPU: Intel Core i7, 6 cores, 2.6 GHz
• Nebula Graph Version: nebula-docker-compose v3.0.1 modified with 1 metad, 1 storaged and 1 graphd

How To Reproduce

Steps to reproduce the behavior:

1. Create a graph as follow: ds1 -> j1 -> ds2 -> j2 -> ds3

# create space
CREATE SPACE IF NOT EXISTS test(vid_type=FIXED_STRING(20));
USE test;

# create schema
CREATE TAG IF NOT EXISTS dataset();
CREATE TAG IF NOT EXISTS job();
CREATE EDGE IF NOT EXISTS lineage();

CREATE TAG INDEX IF NOT EXISTS dataset_index on dataset();
CREATE TAG INDEX IF NOT EXISTS job_index on job();
CREATE EDGE INDEX IF NOT EXISTS lineage_index on lineage();

REBUILD TAG INDEX dataset_index;
REBUILD TAG INDEX job_index;
REBUILD EDGE INDEX lineage_index;

# insert data
INSERT VERTEX dataset() VALUES "ds1":();
INSERT VERTEX dataset() VALUES "ds2":();
INSERT VERTEX dataset() VALUES "ds3":();

INSERT VERTEX job() VALUES "j1":();
INSERT VERTEX job() VALUES "j2":();

INSERT EDGE lineage() VALUES "ds1" -> "j1":(), "j1" -> "ds2":(), "ds2" -> "j2":(), "j2" -> "ds3":();

2. Make queries:

# Query A:
match p = (upstream:dataset) -[:lineage*2]-> (center) return p;

# Result:
+-----------------------------------------------------------------------------------------+
| p                                                                                       |
+-----------------------------------------------------------------------------------------+
| <("ds1" :dataset{})-[:lineage@0 {}]->("j1" :job{})-[:lineage@0 {}]->("ds2" :dataset{})> |
| <("ds2" :dataset{})-[:lineage@0 {}]->("j2" :job{})-[:lineage@0 {}]->("ds3" :dataset{})> |
+-----------------------------------------------------------------------------------------+

# Query B:
match p = (upstream:dataset) -[:lineage*2]-> (center) \
where id(center) == "ds2" \
return p;

# Result:
+-----------------------------------------------------------------------------------------+
| p                                                                                       |
+-----------------------------------------------------------------------------------------+
| <("ds1" :dataset{})-[:lineage@0 {}]->("j1" :job{})<-[:lineage@0 {}]-("ds2" :dataset{})> |
+-----------------------------------------------------------------------------------------+

Expected behavior
The ds2 should have an incoming direction edge started from j1, which was expected in Query A, but Query B has a contrary result.

[wey-gu]

Thanks a lot, @r9liucc for collecting info and bringing this to the community, @CPWstatic will look into it :).