How can do cross-server queries in SQLAlchemy?

Question

I would like to transfer most of my code written on T-SQL to Python, and came across basic data problems that could not be solved by searching in the SQLAlchemy documentation and in other forums.

Question:

How can I implement the following query options with SQLAlchemy (example for the test - below)?

1. select a.field1, a.field2, b.field2 from server1.database1.schema1.table_a as a inner server2.database1.schema1.table_b as b on a.fileld1 = b.fileld1

2. select a.field1, a.field2, b.field2 from server1.database1.schema1.table_a as a inner dataset_variable (**) as b on a.fileld1 = b.fileld1

3. The result of the query - print (select) (see below in the test case) returns an error: sqlalchemy.exc.ProgrammingError: (pyodbc.ProgrammingError) ('42S02', "[42S02] [M icrosoft] [ODBC SQL Server Driver] [SQL Server] Invalid object name 'server2.database1schema1.table_b'.

** Data received from another SQLAlchemy session (server2.database1.schema1.table_b) and stored in the variable dataset_variable

Test connection example: Two linked sql servers are used.

public int[] solution(String S, int[] P, int[] Q){

        int[] result = new int[P.length];

        int[] factor1 = new int[S.length()];
        int[] factor2 = new int[S.length()];
        int[] factor3 = new int[S.length()];
        int[] factor4 = new int[S.length()];

        int factor1Sum = 0;
        int factor2Sum = 0;
        int factor3Sum = 0;
        int factor4Sum = 0;

        for(int i=0; i<S.length(); i++){
            switch (S.charAt(i)) {
            case 'A':
                factor1Sum++;
                break;
            case 'C':
                factor2Sum++;
                break;
            case 'G':
                factor3Sum++;
                break;
            case 'T':
                factor4Sum++;
                break;
            default:
                break;
            }
            factor1[i] = factor1Sum;
            factor2[i] = factor2Sum;
            factor3[i] = factor3Sum;
            factor4[i] = factor4Sum;
        }

        for(int i=0; i<P.length; i++){

            int start = P[i];
            int end = Q[i];

            if(start == 0){
                if(factor1[end] > 0){
                    result[i] = 1;
                }else if(factor2[end] > 0){
                    result[i] = 2;
                }else if(factor3[end] > 0){
                    result[i] = 3;
                }else{
                    result[i] = 4;
                }
            }else{
                if(factor1[end] > factor1[start-1]){
                    result[i] = 1;
                }else if(factor2[end] > factor2[start-1]){
                    result[i] = 2;
                }else if(factor3[end] > factor3[start-1]){
                    result[i] = 3;
                }else{
                    result[i] = 4;
                }
            }

        }

        return result;
    }