prestodb/presto · error · PrestoException

GENERIC_USER_ERROR

GENERIC_USER_ERROR

Error message

Creating schema in Kudu connector not allowed if schema emulation is disabled.

What it means

NoSchemaEmulation.createSchema rejects any schema creation when schema emulation is disabled: the default schema always exists (SchemaAlreadyExistsException) and other names are not allowed at all, throwing GENERIC_USER_ERROR with an explicit message.

Source

Thrown at presto-kudu/src/main/java/com/facebook/presto/kudu/schema/NoSchemaEmulation.java:37

import com.google.common.collect.ImmutableList;
import org.apache.kudu.client.KuduClient;

import java.util.List;

import static com.facebook.presto.kudu.KuduClientSession.DEFAULT_SCHEMA;
import static com.facebook.presto.spi.StandardErrorCode.GENERIC_USER_ERROR;

public class NoSchemaEmulation
        implements SchemaEmulation
{
    @Override
    public void createSchema(KuduClient client, String schemaName)
    {
        if (DEFAULT_SCHEMA.equals(schemaName)) {
            throw new SchemaAlreadyExistsException(schemaName);
        }
        else {
            throw new PrestoException(GENERIC_USER_ERROR, "Creating schema in Kudu connector not allowed if schema emulation is disabled.");
        }
    }

    @Override
    public void dropSchema(KuduClient client, String schemaName)
    {
        if (DEFAULT_SCHEMA.equals(schemaName)) {
            throw new PrestoException(GENERIC_USER_ERROR, "Deleting default schema not allowed.");
        }
        else {
            throw new SchemaNotFoundException(schemaName);
        }
    }

    @Override
    public boolean existsSchema(KuduClient client, String schemaName)
    {
        return DEFAULT_SCHEMA.equals(schemaName);

View on GitHub (pinned to 55bb57d202)

Solutions

  1. Enable schema emulation (kudu.schema-emulation.enabled=true) to allow CREATE SCHEMA
  2. Use the default schema without creating any schema
  3. Redirect the DDL to a connector that supports schemas

Example fix

// session before
CREATE SCHEMA analytics;
// after (with kudu.schema-emulation.enabled=true)
CREATE SCHEMA analytics; -- works once emulation is enabled
Defensive patterns

Strategy: try-catch

Validate before calling

if (catalogConfig.get("kudu.schema-emulation.enabled", "false").equals("false")) {
    throw new IllegalStateException("CREATE SCHEMA not supported: Kudu schema emulation is disabled");
}

Try / catch

try {
    session.createSchema(schemaName);
} catch (PrestoException e) {
    if (e.getMessage().contains("schema emulation is disabled")) {
        log.error("Enable kudu.schema-emulation.enabled=true to use CREATE SCHEMA");
        return;
    }
    throw e;
}

Prevention

When it happens

Trigger: CREATE SCHEMA my_schema; on a Kudu catalog with kudu.schema-emulation.enabled=false (not the default schema, hence this branch).

Common situations: Multi-schema workflows ported from Hive/other connectors; teams unaware the Kudu catalog runs in single-schema mode.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/c378c6a2831748c1. Report an issue: GitHub.