Always backquote column names in CREATE/ATTACH queries

dbms/src/Parsers/ASTColumnDeclaration.cpp

@@ -41,7 +41,9 @@ void ASTColumnDeclaration::formatImpl(const FormatSettings & settings, FormatSta
     frame.need_parens = false;
     std::string indent_str = settings.one_line ? "" : std::string(4 * frame.indent, ' ');
 
-    settings.ostr << settings.nl_or_ws << indent_str << backQuoteIfNeed(name);
+    /// We have to always backquote column names to avoid ambiguouty with INDEX and other declarations in CREATE query.
+    settings.ostr << settings.nl_or_ws << indent_str << backQuote(name);
+
     if (type)
     {
         settings.ostr << ' ';

dbms/src/Parsers/IAST.cpp

@@ -25,7 +25,6 @@ const char * IAST::hilite_alias      = "\033[0;32m";
 const char * IAST::hilite_none       = "\033[0m";
 
 
-/// Quote the identifier with backquotes, if required.
 String backQuoteIfNeed(const String & x)
 {
     String res(x.size(), '\0');
@@ -36,6 +35,16 @@ String backQuoteIfNeed(const String & x)
     return res;
 }
 
+String backQuote(const String & x)
+{
+    String res(x.size(), '\0');
+    {
+        WriteBufferFromString wb(res);
+        writeBackQuotedString(x, wb);
+    }
+    return res;
+}
+
 
 size_t IAST::checkSize(size_t max_size) const
 {

dbms/src/Parsers/IAST.h

@@ -208,7 +208,9 @@ private:
 };
 
 
-/// Surrounds an identifier by back quotes if it is necessary.
+/// Quote the identifier with backquotes, if required.
 String backQuoteIfNeed(const String & x);
+/// Quote the identifier with backquotes.
+String backQuote(const String & x);
 
 }