Random postgresql ?

Hi i have create DQL Function Random in postgresql but not work

```
match(Lexer::T_IDENTIFIER);
$parser->match(Lexer::T_OPEN_PARENTHESIS);
$parser->match(Lexer::T_CLOSE_PARENTHESIS);
}

public function getSql(SqlWalker $sqlWalker)
{
return 'RANDOM()';
}
}
```

```
dql:
numeric_functions:
Random: App\DQL\RandomFunction
```
```
$qb->orderBy('RANDOM()');
```

But got error
Invalid column reference: 7 ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list

i have test
```
public function test(){
return $this->createQueryBuilder('q')->select('q.id')->orderBy('RANDOM()')->setMaxResults(5)->getQuery()->getResult();
}
```

And it works but with paginator no

Thanks for your help

Start with the shown test() query and compare its direct execution with the paginator path, focusing on the PostgreSQL DISTINCT and ORDER BY interaction. Reproduce the failure using the Random DQL function and paginator, then add a regression test showing that random ordering works with pagination without triggering the invalid column reference.

Written by the indexing model from the issue text.