Pros:
- it is convenient to type and read numbers this way;
- Ada, Perl, C++, Go and Rust already support that;
- can support thousands as well as lakhs and crores;

Cons:
- standard SQL does not have this support;
- PostgreSQL treat `SELECT 1_000_000` as number one with `_000_000` alias: http://sqlfiddle.com/#!17/0a28f/400
- C++ has `1'000'000` instead of `1_000_000`;

What do you think?

}
    }
    node = result;
    return true;
}
bool ParserCodecDeclarationList::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
{
    return ParserList(std::make_unique<ParserIdentifierWithOptionalParameters>(),
        std::make_unique<ParserToken>(TokenType::Comma), false).parse(pos, node, expected);
}
bool ParserCodec::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
{
    ParserCodecDeclarationList codecs;
    ASTPtr expr_list_args;
    if (pos->type != TokenType::OpeningRoundBracket)
        return false;
    ++pos;
    if (!codecs.parse(pos, expr_list_args, expected))
        return false;
    if (pos->type != TokenType::ClosingRoundBracket)
        return false;
    ++pos;
    auto function_node = std::make_shared<ASTFunction>();
    function_node->name = "CODEC";
    function_node->arguments = expr_list_args;
    function_node->children.push_back(function_node->arguments);
    node = function_node;
    return true;
}
bool ParserCollation::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)