Aaron199 opened a new issue, #61883:
URL: https://github.com/apache/doris/issues/61883

   ### Search before asking
   
   - [x] I had searched in the 
[issues](https://github.com/apache/doris/issues?q=is%3Aissue) and found no 
similar issues.
   
   
   ### Version
   
   **Environment**
   - **Doris version:** 4.0.3
   - **Deployment:** Kubernetes (k8s) Operator
   - **Cluster Type:** `DorisDisaggregatedCluster` (Cloud Mode / 
Storage-Compute separation)
   - **Configuration:** Catalog property `"use_arrow_flight" = "true"` is set.
   
   ### What's Wrong?
   
   
   **Describe the bug**
   In Doris 4.0.3, when using a cross-cluster Catalog (`type = 'doris'`) with 
the Arrow Flight protocol enabled (`use_arrow_flight = 'true'`) to read data 
from a remote Doris cluster, querying a table that contains a `Variant` column 
fails. The query throws a `NOT_IMPLEMENTED_ERROR`. It appears the underlying 
Arrow reader currently does not support the serialization/deserialization of 
the `Variant` data type.
   
   **To Reproduce**
   1. Create a Catalog connecting to a remote Doris cluster and force enable 
Arrow Flight:
   ```sql
   CREATE CATALOG remote_doris PROPERTIES (
       "type" = "doris",
       "use_arrow_flight" = "true",
       "fe_http_hosts" = "...",
       "fe_arrow_hosts" = "...",
       "fe_thrift_hosts" = "...",
       "user" = "...",
       "password" = "..."
   );
   ```
   2. Ensure the target table being queried on the remote cluster contains a 
column of type `Variant` (e.g., `ext_fields`).
   3. Execute a query from the local cluster via this Catalog:
   ```sql
   SELECT ext_fields FROM remote_doris.db.table LIMIT 10;
   ```
   4. The following error is triggered:
   ```text
   ERROR 1105 (HY000): errCode = 2, detailMessage = 
(...)[NOT_IMPLEMENTED_ERROR]read_column_from_arrow with type variant. cur path: 
/dummyPath
   ```
   *(Note: Even if attempting to use `CAST(ext_fields AS STRING)` in the query, 
the conversion cannot be pushed down before the error occurs, triggering the 
same interception error.)*
   
   
   
   ### What You Expected?
   
   The Arrow Flight transmission link should natively support the cross-cluster 
reading and parsing of `Variant` types, allowing the query to return data 
successfully without throwing a `NOT_IMPLEMENTED_ERROR`.
   
   ### How to Reproduce?
   
   _No response_
   
   ### Anything Else?
   
   _No response_
   
   ### Are you willing to submit PR?
   
   - [ ] Yes I am willing to submit a PR!
   
   ### Code of Conduct
   
   - [x] I agree to follow this project's [Code of 
Conduct](https://www.apache.org/foundation/policies/conduct)
   


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