apache/druid · error · IllegalArgumentException

The table type is required.

Error message

The table type is required.

What it means

TableDefnRegistry.resolve() looks up the table definition registered for a spec's type. The type field is mandatory: without it the registry cannot select a definition, so an empty/null type throws IAE before the lookup.

Source

Thrown at server/src/main/java/org/apache/druid/catalog/model/TableDefnRegistry.java:145

  {
    this(null, null, null, jsonMapper);
  }

  public TableDefn tableDefnFor(String type)
  {
    return tableDefns.get(type);
  }

  public ObjectMapper jsonMapper()
  {
    return jsonMapper;
  }

  public ResolvedTable resolve(TableSpec spec)
  {
    String type = spec.type();
    if (Strings.isNullOrEmpty(type)) {
      throw new IAE("The table type is required.");
    }
    TableDefn defn = tableDefns.get(type);
    if (defn == null) {
      throw new IAE("Table type [%s] is not valid.", type);
    }
    return new ResolvedTable(defn, spec, jsonMapper);
  }

  /**
   * Return input source definition for the given input source type name, or
   * {@code null} if there is no such definition.
   */
  public InputSourceDefn inputSourceDefnFor(String type)
  {
    return inputSourceDefns.get(type);
  }

  /**

View on GitHub (pinned to 9b90983fd2)

Solutions

1. Populate the type field on the TableSpec (e.g. "datasource") before resolving
2. Check the source JSON includes the "type" property and that deserialization binds it
3. Validate the spec (e.g. via TableSpec.validate()) before calling resolve

Example fix

// before
TableSpec spec = new TableSpec(null, props, columns);
registry.resolve(spec);
// after
TableSpec spec = new TableSpec("datasource", props, columns);
registry.resolve(spec);

if (Strings.isNullOrEmpty(spec.type())) {
  throw new IllegalArgumentException("set spec.type before resolve()");
}

boolean isResolvable(TableSpec spec) {
  return spec != null && spec.type() != null && !spec.type().isEmpty();
}

try { return registry.resolve(spec); } catch (IllegalArgumentException e) { if (e.getMessage().equals("The table type is required.")) { /* populate type or reject payload */ } else { throw e; } }

When it happens

Trigger: Calling resolve(TableSpec) — directly or via table(), unsealed(), resolved() helpers — with a TableSpec whose type is null or empty.

Common situations: Deserializing a partial/incomplete table spec from JSON where the "type" field was omitted; building a TableSpec programmatically with a null type; legacy spec formats predating the type field.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Column name is required
• Column %d must have a name
• Database schema is required
• Table name is required
• Table type is required

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/187fb805f56b475f. Report an issue: GitHub.