MyCATApache/Mycat-Server · error · RuntimeException

CallableStatement not supported

Error message

CallableStatement not supported

What it means

MongoConnection.prepareCall unconditionally throws RuntimeException("CallableStatement not supported"). The MongoDB JDBC adapter in MyCat does not implement stored-procedure calls; every overload of prepareCall is a stub. Any code asking this connection for a CallableStatement will always fail.

Solutions

  1. Do not issue CALL / stored-procedure statements against MongoDB-backed nodes; MongoDB has no stored procedures via this adapter
  2. Restrict prepareCall-based data-access code paths to RDBMS backends and use prepareStatement for Mongo nodes
  3. If you only need it not to crash, wrap the call in try-catch for RuntimeException and fall back to prepareStatement
  4. Patch MongoConnection to throw java.sql.SQLFeatureNotSupportedException instead of RuntimeException so JDBC clients can detect and degrade gracefully

Example fix

// before
@Override
public CallableStatement prepareCall(String sql, int resultSetType,
        int resultSetConcurrency, int resultSetHoldability) throws SQLException {
    throw new RuntimeException("CallableStatement not supported");
}

// after
@Override
public CallableStatement prepareCall(String sql, int resultSetType,
        int resultSetConcurrency, int resultSetHoldability) throws SQLException {
    throw new SQLFeatureNotSupportedException("CallableStatement not supported by MongoDB backend");
}
Defensive patterns

Strategy: try-catch

Validate before calling

if (conn instanceof MongoConnection || url.startsWith("jdbc:mongodb")) {
    throw new UnsupportedOperationException("prepareCall is not supported for MongoDB backends; use prepareStatement");
}

Try / catch

try {
    CallableStatement cs = conn.prepareCall(sql);
} catch (RuntimeException e) {
    if (e.getMessage() != null && e.getMessage().contains("CallableStatement not supported")) {
        // fall back to PreparedStatement-based execution
    } else {
        throw e;
    }
}

Prevention

When it happens

Trigger: Calling connection.prepareCall(String), prepareCall(String,int,int), or prepareCall(String,int,int,int) on a MongoConnection obtained via MongoDriver.connect for URL scheme mongodb://.

Common situations: Configuring MyCat with a MongoDB backend JDBC node and then running SQL that the MyCat planner routes to a stored-procedure CALL statement; reusing generic JDBC data-access code (e.g. frameworks that probe prepareCall) against a Mongo backend.

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 MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/6d5ecdcb2cb79c08. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/backend/jdbc/mongodb/MongoConnection.java:254

	public CallableStatement prepareCall(String sql) throws SQLException {
		
		return prepareCall(sql, 0, 0, 0);
	}
	
	@Override
	public CallableStatement prepareCall(String sql, int resultSetType,
			int resultSetConcurrency) throws SQLException {
		
		return prepareCall(sql, resultSetType, resultSetConcurrency, 0);
	}

	@Override
	public CallableStatement prepareCall(String sql, int resultSetType,
			int resultSetConcurrency, int resultSetHoldability)
			throws SQLException {
		
		//return null;
		throw new RuntimeException("CallableStatement not supported");
	}
	
	@Override
	public PreparedStatement prepareStatement(String sql) throws SQLException {
		
		return prepareStatement(sql, 0, 0, 0);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType,
			int resultSetConcurrency) throws SQLException {
		
		return prepareStatement(sql, resultSetType, resultSetConcurrency, 0);
	}

	@Override
	public PreparedStatement prepareStatement(String sql, int resultSetType,
			int resultSetConcurrency, int resultSetHoldability)

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