```
CREATE TABLE a
(
    `number` UInt64,
    `x` MATERIALIZED x
)
ENGINE = MergeTree
ORDER BY number;
-- that should fail!

insert into a values (1);
Received exception from server (version 21.7.1):
Code: 47. DB::Exception: Received from localhost:9000. DB::Exception: Missing columns: 'x' while processing query: 'CAST(x, 'UInt8') AS x', required columns: 'x' 'x'. 
```
writeChar('\n', buf);
}
void ColumnDescription::readText(ReadBuffer & buf)
{
    readBackQuotedString(name, buf);
    assertChar(' ', buf);
    String type_string;
    readEscapedString(type_string, buf);
    type = DataTypeFactory::instance().get(type_string);
    if (checkChar('\t', buf))
    {
        String modifiers;
        readEscapedStringUntilEOL(modifiers, buf);
        ParserColumnDeclaration column_parser( true);
        ASTPtr ast = parseQuery(column_parser, "x T " + modifiers, "column parser", 0, DBMS_DEFAULT_MAX_PARSER_DEPTH);
        if (const auto * col_ast = ast->as<ASTColumnDeclaration>())
        {
            if (col_ast->default_expression)
            {
                default_desc.kind = columnDefaultKindFromString(col_ast->default_specifier);
                default_desc.expression = std::move(col_ast->default_expression);
            }
            if (col_ast->comment)
                comment = col_ast->comment->as<ASTLiteral &>().value.get<String>();
            if (col_ast->codec)
                codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(col_ast->codec, type, false, true);
            if (col_ast->ttl)
                ttl = col_ast->ttl;
        }
        else