googleapis/mcp-toolbox · error

unclosed backtick identifier

Error message

unclosed backtick identifier

What it means

parseIdentifierSequence parses dotted identifiers and supports backtick-quoted parts. When a part starts with a backtick but no closing backtick exists anywhere after it, the identifier is unterminated and cannot be extracted, so parsing fails with this error.

Source

Thrown at internal/tools/bigquery/bigquerycommon/table_name_parser.go:421

	var totalConsumed int

	for {
		remaining := s[totalConsumed:]
		trimmed := strings.TrimLeftFunc(remaining, unicode.IsSpace)
		totalConsumed += len(remaining) - len(trimmed)
		current := s[totalConsumed:]

		if len(current) == 0 {
			break
		}

		var part string
		var consumed int

		if current[0] == '`' {
			end := strings.Index(current[1:], "`")
			if end == -1 {
				return nil, 0, fmt.Errorf("unclosed backtick identifier")
			}
			part = current[1 : end+1]
			consumed = end + 2
		} else if len(current) > 0 && unicode.IsLetter(rune(current[0])) {
			end := strings.IndexFunc(current, func(r rune) bool {
				return !unicode.IsLetter(r) && !unicode.IsNumber(r) && r != '_' && r != '-'
			})
			if end == -1 {
				part = current
				consumed = len(current)
			} else {
				part = current[:end]
				consumed = end
			}
		} else {
			break
		}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Add the missing closing backtick to the quoted identifier
2. Remove backticks entirely if the identifier contains no special characters (project/dataset/table names are usually unquoted-safe)
3. Check that templating/escaping layers (YAML, shell) are not eating the closing backtick
4. Use straight ASCII backticks, not typographic quotes

Example fix

// before
SELECT * FROM `proj.ds.t;
// after
SELECT * FROM `proj.ds.t`;

func backticksClosed(sql string) bool {
    return strings.Count(sql, "`")%2 == 0
}

if !backticksClosed(sql) {
    return fmt.Errorf("query has an unclosed backtick identifier")
}
_, err := parser.Parse(sql)
if err != nil {
    return err
}

When it happens

Trigger: A table name like `project.dataset.table` missing the closing backtick passed through parseSQL, e.g. `proj`.`ds.t or a lone stray backtick before a table name.

Common situations: String templates that forget to close backticks; quotes stripped by shell or YAML escaping; copy-paste from docs that mangles backticks; accidental smart-quote substitution.

Related errors

• EXECUTE IMMEDIATE is not allowed when dataset restrictions a
• unanalyzable statements like '%s %s' are not allowed
• dataset-level operations like '%s %s' are not allowed when d
• unclosed subquery parenthesis
• query contains table '%s' without project ID, and no default

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/42d42d0e14035220. Report an issue: GitHub.