This error occurs when a SQL statement or feature is incompatible with the current execution mode in MaxCompute. Each variant has a distinct cause and resolution.
SESSION2 fallback from service mode to offline mode since there is udf in the map task
Error message:
ODPS-1850001: Unsupported feature in session mode - SESSION2 switches from service mode to offline mode because a UDF is present in the map task.Cause:
SESSION2 detected a User-Defined Function (UDF) in the map task and fell back from service mode to offline mode.
Solution:
For common SQL jobs, this fallback does not affect the job result — the job continues to run in offline mode. However, if Query Acceleration (MaxQA/MCQA) is enabled, the task fails and does not execute.
To prevent Query Acceleration tasks from failing, disable query acceleration before the SQL statement:
set odps.mcqa.disable=true;
Non select query not supported
Error message:
ODPS-1850001: Unsupported feature in session mode - Non-select queries are not supported.Cause:
A Data Manipulation Language (DML) statement was executed in MCQA (Query Acceleration 1.0) mode.
This limitation applies only to MCQA. MaxQA (Query Acceleration 2.0) supports all SQL statement types (DDL, DQL, and DML). For more information, see MaxQA overview.
Solution:
Disable query acceleration mode before running DML statements.