databendlabs/databend · error

replace with streaming not supported yet

Error message

replace with streaming not supported yet

What it means

The REPLACE interpreter does not support streaming-load input sources at all. If a REPLACE statement's input is InsertInputSource::StreamingLoad (the MySQL-style streaming insert channel), the code hits unreachable! and panics, because REPLACE requires a fully formed query or stage source instead of an inline stream.

Solutions

1. Rewrite the statement to REPLACE INTO ... SELECT ... from an existing table instead of streaming rows.
2. First INSERT-stream the rows into a staging table, then run REPLACE INTO target SELECT * FROM staging.
3. Use a driver/statement form that produces a query-based source for REPLACE.

-- Rewrite streaming REPLACE into table-then-merge:
INSERT INTO staging_table VALUES (...);
REPLACE INTO target SELECT * FROM staging_table;

When it happens

Trigger: Issuing a REPLACE statement whose input plan comes through the streaming-load path (e.g. REPLACE INTO combined with a streaming write), rather than a SELECT/query or stage COPY source.

Common situations: Client drivers or connectors that stream row data inline attempting REPLACE; tools that generalize INSERT streaming logic to REPLACE statements.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Input plan must be Query, but it's
• internal error: entered unreachable code
• create_procedure: CreateOrReplace should never conflict…
• plan in InsertInputSource::Stag must be CopyIntoTable
• Input plan must be Query, but it's

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/33a38375833486f2. Report an issue: GitHub.

Appendix: source

Thrown at src/query/service/src/interpreters/interpreter_replace.rs:451

                        copy_plan.stage_table_info.files_to_copy.unwrap_or_default(),
                        copy_plan.stage_table_info.stage_info.clone(),
                        copy_plan.stage_table_info.copy_into_table_options.clone(),
                    ));
                    Ok(ReplaceSourceCtx {
                        root: physical_plan,
                        select_ctx: None,
                        update_stream_meta: vec![],
                        bind_context: None,
                    })
                }
                _ => unreachable!("plan in InsertInputSource::Stag must be CopyIntoTable"),
            },
            #[cfg(not(feature = "storage-stage"))]
            InsertInputSource::Stage(_) => Err(ErrorCode::Unimplemented(
                "Stage COPY source support is disabled, rebuild with cargo feature 'storage-stage'",
            )),
            InsertInputSource::StreamingLoad { .. } => {
                unreachable!("replace with streaming not supported yet")
            }
        }
    }

    fn connect_value_source(
        &self,
        schema: DataSchemaRef,
        source: &InsertValue,
    ) -> Result<PhysicalPlan> {
        Ok(PhysicalPlan::new(ReplaceAsyncSourcer {
            schema,
            source: source.clone(),
            meta: PhysicalPlanMeta::new("ReplaceAsyncSourcer"),
        }))
    }

    #[async_backtrace::framed]
    async fn connect_query_plan_source<'a>(

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