What causes "Namespace with name ''+namespace+'' already exists" in pentaho/pentaho-kettle?

Call namespaceExists(name) first and skip creation if it returns true

pentaho/pentaho-kettle · warning · MetaStoreNamespaceExistsException

Namespace with name ''+namespace+'' already exists

Error message

Namespace with name ''+namespace+'' already exists

What it means

createNamespace() first looks up the namespace by name; if a row already exists it throws MetaStoreNamespaceExistsException('Namespace with name X already exists'). This is a deliberate guard so namespaces remain unique in R_NAMESPACE.

Solutions

Call namespaceExists(name) first and skip creation if it returns true
Catch MetaStoreNamespaceExistsException and treat it as a no-op when idempotent setup is intended
Use a distinct namespace name if a genuinely new namespace is required

Example fix

// before
metaStore.createNamespace("pentaho"); // throws on second run
// after
if (!metaStore.namespaceExists("pentaho")) {
  metaStore.createNamespace("pentaho");
}

Defensive patterns

Strategy: validation

Validate before calling

if (!metaStore.namespaceExists(namespace)) {
  metaStore.createNamespace(namespace);
}

Try / catch

try { metaStore.createNamespace(ns); } catch (MetaStoreNamespaceExistsException e) { /* idempotent: already exists, ignore */ }

Prevention

Make setup code idempotent: check existence before create
Serialize namespace creation in concurrent jobs to avoid races
Use try/catch on MetaStoreNamespaceExistsException for one-time initialization scripts

When it happens

Trigger: metastore.createNamespace(name) where delegate.getNamespaceId(name) returns a non-null id, i.e. the namespace name already exists in the repository.

Common situations: Initialization code that runs on every startup calling createNamespace unconditionally; two jobs racing to create the same namespace; re-running a setup script after partial execution.

Understand the failure class

Background: "already exists" / EEXIST / FileAlreadyExistsException: what the 'file already exists' error means and how to fix it — this error's family across 37 libraries.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/cd376bd3ad87959d. Report an issue: GitHub.

Appendix: source

Thrown at engine/src/main/java/org/pentaho/di/repository/kdr/delegates/metastore/KettleDatabaseRepositoryMetaStore.java:79

      for ( RowMetaAndData namespaceRow : namespaceRows ) {
        String namespace = namespaceRow.getString( KettleDatabaseRepository.FIELD_NAMESPACE_NAME, null );
        if ( !Utils.isEmpty( namespace ) ) {
          namespaces.add( namespace );
        }
      }
      return namespaces;

    } catch ( Exception e ) {
      throw new MetaStoreException( e );
    }
  }

  @Override
  public void createNamespace( String namespace ) throws MetaStoreException, MetaStoreNamespaceExistsException {
    try {
      ObjectId namespaceId = delegate.getNamespaceId( namespace );
      if ( namespaceId != null ) {
        throw new MetaStoreNamespaceExistsException( "Namespace with name '" + namespace + "' already exists" );
      }

      // insert namespace into R_NAMESPACE
      //
      delegate.insertNamespace( namespace );
      repository.commit();
    } catch ( Exception e ) {
      repository.rollback();
      throw new MetaStoreException( e );
    }
  }

  @Override
  public void deleteNamespace( String namespace ) throws MetaStoreException, MetaStoreDependenciesExistsException {
    try {
      ObjectId namespaceId = delegate.verifyNamespace( namespace );

      List<IMetaStoreElementType> elementTypes = getElementTypes( namespace );

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