What causes "non shared source has no fragments to describe" in risingwavelabs/risingwave?

Use `DESCRIBE ` instead to inspect schema

risingwavelabs/risingwave · error · ErrorCode::NotSupported

non shared source has no fragments to describe

Error message

non shared source has no fragments to describe

What it means

`DESCRIBE FRAGMENTS` shows the streaming fragments of a shared source or streaming job. Non-shared (single-node) sources have no independently managed fragments, so the handler rejects the command and points users to plain `DESCRIBE`.

Solutions

Use `DESCRIBE <source_name>` instead to inspect schema
If fragment inspection is needed, recreate or configure the source as shared (`CREATE SHARED SOURCE ...` or enable shared source in config)
Use `EXPLAIN` / `SHOW FRAGMENTS` on the relevant MV or job instead

Example fix

// before
DESCRIBE FRAGMENTS my_source;
// after
DESCRIBE my_source;

Defensive patterns

Strategy: validation

Validate before calling

-- shared sources can be listed; only run DESCRIBE FRAGMENTS on those
SELECT name FROM rw_catalog.rw_sources WHERE ...;

Try / catch

catch NotSupported with hint 'Use DESCRIBE instead of DESCRIBE FRAGMENTS' and fall back to DESCRIBE

Prevention

Use DESCRIBE FRAGMENTS only on shared sources or streaming jobs
Default to plain DESCRIBE when unsure of relation type

When it happens

Trigger: Running `DESCRIBE FRAGMENTS <source_name>` where `<source_name>` resolves to a source created without shared-source support (e.g. a non-shared Kafka source, or shared source disabled in config).

Common situations: Trying to inspect execution plans of a regular source; confusion between shared vs non-shared sources; older sources created before shared sources were enabled.

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

AI-assisted analysis of risingwavelabs/risingwave@6469eb736d (2026-09-11). Data as JSON: /api/errors/3401dee27c1d9d42. Report an issue: GitHub.

Appendix: source

Thrown at src/frontend/src/handler/describe.rs:290

pub async fn handle_describe_fragments(
    handler_args: HandlerArgs,
    object_name: ObjectName,
) -> Result<RwPgResponse> {
    let session = handler_args.session.clone();
    let job_id = {
        let mut binder = Binder::new_for_system(&session);

        Binder::validate_cross_db_reference(&session.database(), &object_name)?;
        let not_found_err = CatalogError::not_found("stream job", object_name.to_string());

        if let Ok(relation) = binder.bind_catalog_relation_by_object_name(&object_name, true) {
            match relation {
                Relation::Source(s) => {
                    if s.is_shared() {
                        s.catalog.id.as_share_source_job_id()
                    } else {
                        bail!(ErrorCode::NotSupported(
                            "non shared source has no fragments to describe".to_owned(),
                            "Use `DESCRIBE` instead of `DESCRIBE FRAGMENTS`".to_owned(),
                        ));
                    }
                }
                Relation::BaseTable(t) => t.table_catalog.id.as_job_id(),
                Relation::SystemTable(_t) => {
                    bail!(ErrorCode::NotSupported(
                        "system table has no fragments to describe".to_owned(),
                        "Use `DESCRIBE` instead of `DESCRIBE FRAGMENTS`".to_owned(),
                    ));
                }
                Relation::Share(_s) => {
                    bail!(ErrorCode::NotSupported(
                        "view has no fragments to describe".to_owned(),
                        "Use `DESCRIBE` instead of `DESCRIBE FRAGMENTS`".to_owned(),
                    ));
                }

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