ExeuctionFailed: Cannot invoke "RelationshipDataAcessor.type" because "v3_relationships" is null

DominicWuest commented 1 year ago

When running the following query:

CALL {  CREATE ()-[:A]->() } MATCH ()-[:(B & C)]->(:!(D & E)) RETURN 0

I encountered the following error:

Neo4jError: Neo.DatabaseError.Statement.ExecutionFailed (Cannot invoke "org.neo4j.internal.kernel.api.RelationshipDataAccessor.type()" because "this.v3_relationships" is null)

I believe the query mentioned above is semantically and syntactically correct and thus no error should be thrown here.

I encountered this issue when testing queries against the Neo4j 5.6.0 enterprise version in a Docker container running alpine v.3.

Steps to reproduce

Run the following queries and observe it throws an error:

CALL {  CREATE ()-[:A]->() } MATCH ()-[:(B & C)]->(:!(D & E)) RETURN 0

Expected behavior

The query should run successfully

Actual behavior

The query fails with the error message Neo4jError: Neo.DatabaseError.Statement.ExecutionFailed (Cannot invoke "org.neo4j.internal.kernel.api.RelationshipDataAccessor.type()" because "this.v3_relationships" is null)

InverseFalcon commented 1 year ago

This appears to be a PIPELINED runtime bug.

If I force SLOTTED runtime instead by prefixing with CYPHER runtime=SLOTTED then the query is able to run.

loveleif commented 1 year ago

Thanks @DominicWuest! I've created a ticket in our internal bug tracker for further investigation (link).

sherfert commented 1 year ago

@DominicWuest We have found and fixed the issue and the fix will be part of 5.9 I could not reproduce the issue on 4.4.

DominicWuest commented 7 months ago

Hello @sherfert! I hope I'm not bothering you, but would it be possible to get a quick explanation of what caused this bug?

sherfert commented 7 months ago

Sure. This was a bug in the planner. Before the bugfix, the query was planned like this:

+-----------------------------------+----+---------------------------------------------------+----------------+---------------------+
| Operator                          | Id | Details                                           | Estimated Rows | Pipeline            |
+-----------------------------------+----+---------------------------------------------------+----------------+---------------------+
| +ProduceResults                   |  0 | `0`                                               |              0 |                     |
| |                                 +----+---------------------------------------------------+----------------+                     |
| +Projection                       |  1 | $autoint_0 AS `0`                                 |              0 |                     |
| |                                 +----+---------------------------------------------------+----------------+                     |
| +Expand(Into)                     |  2 | (a)-[r:C]->(b)                                    |              0 |                     |
| |                                 +----+---------------------------------------------------+----------------+                     |
| +Filter                           |  3 | r:B                                               |              0 |                     |
| |                                 +----+---------------------------------------------------+----------------+                     |
| +Apply                            |  4 |                                                   |              0 |                     |
| |\                                +----+---------------------------------------------------+----------------+                     |
| | +Distinct                       |  5 | r, a, b                                           |              0 |                     |
| | |                               +----+---------------------------------------------------+----------------+                     |
| | +Union                          |  6 |                                                   |              0 | Fused in Pipeline 6 |
| | |\                              +----+---------------------------------------------------+----------------+---------------------+
| | | +Filter                       |  7 | not b:E                                           |              0 |                     |
| | | |                             +----+---------------------------------------------------+----------------+                     |
| | | +DirectedAllRelationshipsScan |  8 | (a)-[r]->(b)                                      |              3 | Fused in Pipeline 5 |
| | |                               +----+---------------------------------------------------+----------------+---------------------+
| | +Filter                         |  9 | not b:D                                           |              0 |                     |
| | |                               +----+---------------------------------------------------+----------------+                     |
| | +DirectedAllRelationshipsScan   | 10 | (a)-[r]->(b)                                      |              3 | Fused in Pipeline 4 |
| |                                 +----+---------------------------------------------------+----------------+---------------------+
| +Eager                            | 11 |                                                   |              1 | In Pipeline 3       |
| |                                 +----+---------------------------------------------------+----------------+---------------------+
| +SubqueryForeach                  | 12 |                                                   |              1 |                     |
| |\                                +----+---------------------------------------------------+----------------+                     |
| | +Create                         | 13 | (anon_0), (anon_2), (anon_0)-[anon_1:A]->(anon_2) |              1 | Fused in Pipeline 1 |
| |                                 +----+---------------------------------------------------+----------------+---------------------+
| +EmptyRow                         | 15 |                                                   |              1 | In Pipeline 0       |
+-----------------------------------+----+---------------------------------------------------+----------------+---------------------+

Note how the Expand(Into) with Id 2 overwrites the existing column r. That is not allowed.

It now gets planned as

+---------------------------------+----+---------------------------------------------------+----------------+---------------------+
| Operator                        | Id | Details                                           | Estimated Rows | Pipeline            |
+---------------------------------+----+---------------------------------------------------+----------------+---------------------+
| +ProduceResults                 |  0 | `0`                                               |              0 |                     |
| |                               +----+---------------------------------------------------+----------------+                     |
| +Projection                     |  1 | $autoint_0 AS `0`                                 |              0 |                     |
| |                               +----+---------------------------------------------------+----------------+                     |
| +Filter                         |  2 | anon_4:B AND (NOT anon_5:D OR NOT anon_5:E)       |              0 |                     |
| |                               +----+---------------------------------------------------+----------------+                     |
| +Apply                          |  3 |                                                   |              3 |                     |
| |\                              +----+---------------------------------------------------+----------------+                     |
| | +DirectedRelationshipTypeScan |  4 | (anon_3)-[anon_4:C]->(anon_5)                     |              3 | Fused in Pipeline 4 |
| |                               +----+---------------------------------------------------+----------------+---------------------+
| +Eager                          |  5 |                                                   |              1 | In Pipeline 3       |
| |                               +----+---------------------------------------------------+----------------+---------------------+
| +SubqueryForeach                |  6 |                                                   |              1 |                     |
| |\                              +----+---------------------------------------------------+----------------+                     |
| | +Create                       |  7 | (anon_0), (anon_2), (anon_0)-[anon_1:A]->(anon_2) |              1 | Fused in Pipeline 1 |
| |                               +----+---------------------------------------------------+----------------+---------------------+
| +EmptyRow                       |  9 |                                                   |              1 | In Pipeline 0       |
+---------------------------------+----+---------------------------------------------------+----------------+---------------------+

which is a valid plan.

DominicWuest commented 7 months ago

Awesome, thank you for the explanation!

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