[jira] [Created] (FLINK-39913) Improve the error message when a foreground query emits an upsert changelog

["Ramin Gharib (Jira)" <ji...@apache.org>]

Ramin Gharib created FLINK-39913:
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             Summary: Improve the error message when a foreground query emits an upsert changelog
                 Key: FLINK-39913
                 URL: https://issues.apache.org/jira/browse/FLINK-39913
             Project: Flink
          Issue Type: Improvement
          Components: Table SQL / API, Table SQL / Planner
            Reporter: Ramin Gharib
            Assignee: Ramin Gharib


A foreground query (a bare SELECT, collected with no primary key) over a relation that emits an upsert changelog fails with an unhelpful error. The message is just "Can't generate a valid execution plan" followed by the optimized plan. A user has no way  to tell what went wrong or how to fix it.                                                                                       
                                                                                                                                  
The plan can emit an upsert changelog, for example via FROM_CHANGELOG with PARTITION BY and an op_mapping that has no UPDATE_BEFORE. The foreground sink has no primary key, so the planner requires a retract changelog (UPDATE_BEFORE + UPDATE_AFTER). Upsert cannot satisfy that, and the planner gives up.

Reproduce:
{code:java}
SELECT *
FROM FROM_CHANGELOG(
  input => TABLE events PARTITION BY id,
  op    => DESCRIPTOR(operation),
  op_mapping => MAP[
    'c', 'INSERT',
    'u', 'UPDATE_AFTER',
    'd', 'DELETE'
  ]
); {code}

Part of the error message the users sees is:
{code:java}
Can't generate a valid execution plan for the given query:
    Sink(table=[*anonymous_foreground-sink$112*], fields=[id, name, email, status, event_time], changelogMode=[NONE])
...{code}
 

 

 



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