googleapis/mcp-toolbox · error

unable to execute query: %w

Error message

unable to execute query: %w

What it means

RunSQL wraps any error returned by sql.DB.QueryContext with this message. The pool accepted the query but the driver failed to execute it — this includes connection-level failures at query time as well as SQL syntax and permission errors reported by SingleStore. No rows are returned; the whole invocation fails.

Source

Thrown at internal/sources/singlestore/singlestore.go:118

}

func (s *Source) SourceType() string {
	return SourceType
}

func (s *Source) ToConfig() sources.SourceConfig {
	return s.Config
}

// SingleStorePool returns the underlying *sql.DB connection pool for SingleStore.
func (s *Source) SingleStorePool() *sql.DB {
	return s.Pool
}

func (s *Source) RunSQL(ctx context.Context, statement string, params []any) (any, error) {
	results, err := s.SingleStorePool().QueryContext(ctx, statement, params...)
	if err != nil {
		return nil, fmt.Errorf("unable to execute query: %w", err)
	}

	cols, err := results.Columns()
	if err != nil {
		return nil, fmt.Errorf("unable to retrieve rows column name: %w", err)
	}

	// create an array of values for each column, which can be re-used to scan each row
	rawValues := make([]any, len(cols))
	values := make([]any, len(cols))
	for i := range rawValues {
		values[i] = &rawValues[i]
	}
	defer results.Close()

	colTypes, err := results.ColumnTypes()
	if err != nil {
		return nil, fmt.Errorf("unable to get column types: %w", err)

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Run the exact statement in the `mysql` CLI against the same database to see the underlying SQL error.
2. Check the wrapped driver error in the message for the real cause (syntax, access denied, connection lost).
3. Use `?` placeholders for parameters and pass values via the tool's params field.
4. Ensure the configured user has privileges for the statement (SELECT/INSERT/DDL as needed).
5. If the error is connection-related, reinitialize the source or enable keepalives / tune readTimeout.

Example fix

// before (invalid placeholder syntax)
{"statement": "SELECT * FROM t WHERE id = $1", "params": ["7"]}
// after
{"statement": "SELECT * FROM t WHERE id = ?", "params": ["7"]}

// Validate the statement shape before invoking run-sql
func validateStatement(stmt string) error {
    s := strings.TrimSpace(stmt)
    if s == "" { return errors.New("empty statement") }
    if strings.Contains(s, "$"+"1") || strings.Contains(s, "%s") { return errors.New("use ? placeholders") }
    return nil
}

result, err := source.RunSQL(ctx, stmt, params)
if err != nil {
    if strings.Contains(err.Error(), "connection refused") || strings.Contains(err.Error(), "driver: bad connection") {
        // reconnect/reinitialize then retry once
    }
    return fmt.Errorf("run-sql failed: %w", err)
}

When it happens

Trigger: Calling the run-sql tool against a SingleStore source when the statement is invalid, the connection has dropped since initialization, the user lacks privileges, or params cannot be interpolated into the statement.

Common situations: Typos in SQL, referencing a non-existent table, executing DDL/DML without grants, using placeholder syntax the driver dislikes (should be `?`), or idle connection killed by a firewall between init and query.

Related errors

• unable to execute query: %w
• unable to retrieve rows column name: %w
• unable to get column types: %w
• unable to parse row: %w
• errors encountered when converting values: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/7f76b37dfcc8355f. Report an issue: GitHub.