While it is a good idea to deliver session tracking information, it is quite a bad idea to remove the intermediate EOF packet, since applications which use unbuffered result sets will break ( text and binary protocol)

Simple example:

  mysql_real_connect(mysql, "127.0.0.1", NULL, NULL, "test", 0, NULL, CLIENT_MULTI_STATEMENTS | CLIENT_MULTI_RESULTS);

  if (mysql_errno(mysql))

  {

    printf("Error: %s\n", mysql_error(mysql));

    exit(-1);

  }

  mysql_query(mysql, "SELECT 1;SELECT 2");

  res= mysql_use_result(mysql);

  /* if there are more results, skip first result */

  if (mysql_more_results(mysql))

  {

    mysql_free_result(res);

    mysql_next_result(mysql);

    res= mysql_use_result(mysql);

  }

  row= mysql_fetch_row(res);

  printf("Value: %s\n", row[0]);

  mysql_free_result(res);

Output:

without CLIENT_DEPRECATED_EOF:
Value: 2

with CLIENT_DEPRECATED_EOF:
Value: 1

As per the docs, this works with unbuffered fetch too. The reason for the bad result above is you're not fetching results as per the docs.

The mysql_use_result docs say:

> When using mysql_use_result(), you must execute mysql_fetch_row() until a NULL value is returned, otherwise, the unfetched rows are returned as part of the result set for your next query. The C API gives the error Commands out of sync; you can't run this command now if you forget to do this!

The following code returns right results with unbuffered fetch for example:

  MYSQL_RES* res;

  MYSQL_ROW row;

  mysql_query(mysql, "SELECT 1;SELECT 2");

  res= mysql_use_result(mysql);

  while (row= mysql_fetch_row(res)) {

    printf("Value first time: %s\n", row[0]);

  }

  mysql_free_result(res);

  if (mysql_more_results(mysql))

  {

    mysql_next_result(mysql);

    res= mysql_use_result(mysql);

    while (row= mysql_fetch_row(res)) {

      printf("Value second time: %s\n", row[0]);

    }

    mysql_free_result(res);

  }

Output:

Value first time: 1

Value second time: 2

I tested this with my PR with CLIENT_DEPRECATE_EOF support in https://github.com/mariadb-corporation/mariadb-connector-c/pull/131.

I know that it works when fetching all rows to get the last ok packet, but this will break a lot of applications.
Imho this design is broken, and will not be implemented.

See also MySQL bug #100279

Won't do, because breaking existing application