What causes "SET CONFIG is only supported for materialized views" in risingwavelabs/risingwave?

Use `ALTER MATERIALIZED VIEW SET CONFIG (...);` instead

SET CONFIG is only supported for materialized views

Error message

SET CONFIG is only supported for materialized views

What it means

`ALTER ... SET CONFIG` adjusts streaming configuration of a streaming job, which only materialized views have. When the altered object is a plain view (not materialized), the handler rejects the operation.

Solutions

Use `ALTER MATERIALIZED VIEW <name> SET CONFIG (...);` instead
Confirm the object is an MV via `SHOW MATERIALIZED VIEWS LIKE '<name>';`
For plain views, change the underlying query definition with `ALTER VIEW <name> AS <query>` instead

Example fix

// before
ALTER VIEW my_v SET CONFIG (streaming_use_fetch_operator = true);
// after
ALTER MATERIALIZED VIEW my_mv SET CONFIG (streaming_use_fetch_operator = true);

Defensive patterns

Strategy: validation

Validate before calling

SELECT name FROM rw_catalog.rw_mviews WHERE name = 'my_object';
-- only proceed with ALTER ... SET CONFIG if a row exists

Prevention

Use ALTER MATERIALIZED VIEW ... SET CONFIG for streaming config changes
Confirm object type with SHOW MATERIALIZED VIEWS before ALTER
For plain views use ALTER VIEW ... AS <query> instead

When it happens

Trigger: Running `ALTER VIEW <name> SET CONFIG (<key> = <value>)` where `<name>` is a regular VIEW created via `CREATE VIEW`.

Common situations: Mixing up `ALTER VIEW` and `ALTER MATERIALIZED VIEW` syntax; copy-pasting tuning commands between views and MVs.

Related errors

AI-assisted analysis of risingwavelabs/risingwave@6469eb736d (2026-09-11). Data as JSON: /api/errors/917c4dfeb298aa91. Report an issue: GitHub.

Appendix: source

Thrown at src/frontend/src/handler/mod.rs:1224

                        bail!(
                            "ALTER VIEW SET STREAMING_ENABLE_UNALIGNED_JOIN is not supported. Only supported for materialized views"
                        );
                    }
                    alter_streaming_enable_unaligned_join::handle_alter_streaming_enable_unaligned_join(handler_args, name, enable).await
                }
                AlterViewOperation::AsQuery { query } => {
                    if !materialized {
                        bail_not_implemented!("ALTER VIEW AS QUERY");
                    }
                    // `ALTER MATERIALIZED VIEW AS QUERY` is only available in development build now.
                    if !cfg!(debug_assertions) {
                        bail_not_implemented!("ALTER MATERIALIZED VIEW AS QUERY");
                    }
                    alter_mv::handle_alter_mv(handler_args, name, query).await
                }
                AlterViewOperation::SetConfig { entries } => {
                    if !materialized {
                        bail!("SET CONFIG is only supported for materialized views");
                    }
                    alter_streaming_config::handle_alter_streaming_set_config(
                        handler_args,
                        name,
                        entries,
                        statement_type,
                    )
                    .await
                }
                AlterViewOperation::ResetConfig { keys } => {
                    if !materialized {
                        bail!("RESET CONFIG is only supported for materialized views");
                    }
                    alter_streaming_config::handle_alter_streaming_reset_config(
                        handler_args,
                        name,
                        keys,
                        statement_type,

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