Inconsistent behavior for binder error (hashtag2804)

[vikramsubramanian]

I have an RDFGraph named wklx. I am running the following query:

match (s:wklx_r)-[p:wklx_rt]->(o) return s.iri, p.iri, o.iri, o.val limit 10;

This does not give a binding error and instead prints a val column with null values. I was expecting it because o can only be of type wklx_r and that does not have val property. If I specify the type, then I get a binding error.

match (s:wklx_r)-[p:wklx_rt]->(o:wklx_r) return s.iri, p.iri, o.iri, o.val limit 10;
Error: Binder exception: Cannot find property val for o.

It's not clear if we should give a binder error or but I think a smart system would by resolving the possible types first. My bigger worry is that if we are not doing such type resolutions, we might end up doing unnecessary joins (e.g., by scanning both wklx_r and wklx_l tables to bind to o). That is I can imagine not doing type resolutions correctly can decrease performance significantly in some cases. )

[mayil-ai[bot]]

Summary: Inconsistent behavior with binding error for RDFGraph query.

Possible Solution

Based on the provided information, the issue seems to be related to the inability of the query execution engine to find the property val for the variable o when a type specification is included in the query. The error message Error: Binder exception: Cannot find property val for o. indicates that the binder is unable to resolve the property val for the specified type.

To address this issue, consider the following solution:

• Verify the schema of the wklx_r type to ensure that the property val exists. If the property does not exist, it may be necessary to update the schema or adjust the query to reference a valid property.
• If the property val does exist for the wklx_r type, inspect the binder logic in the src/binder/bind/copy/bind_copy_rdf_graph.cpp file to ensure that it correctly resolves properties for nodes of type wklx_r. Specifically, check the logic that binds the val property to ensure it is correctly handling type specifications in queries.
• Ensure that the binder is correctly differentiating between resource nodes and literal nodes, as the property val may only be present on one of these types. The binder should correctly identify the type of node o is when the type specification is provided.
• If the val property is specific to literals and not resources, the binder logic may need to be adjusted to correctly handle queries that involve both resource and literal nodes, ensuring that properties are accessed from the correct node type.

If the val property is indeed missing from the wklx_r type, the query should be corrected to avoid referencing non-existent properties. If the property exists but is not being resolved correctly, the binder logic will need to be updated to handle type specifications properly.

Code snippets to check

• src/binder/bind/copy/bind_copy_rdf_graph.cpp

  This file contains logic related to RDF graph binding and scanning, which is directly related to the issue of inconsistent behavior for binder errors and potential unnecessary joins due to type resolutions.

• src/binder/bind/copy/bind_copy_rdf_graph.cpp

  This snippet also pertains to the binding and scanning of RDF graphs, which may need to be reviewed to ensure correct type resolutions and to avoid performance issues.