[MDEV-18281] COM_RESET_CONNECTION change the connection encoding Created: 2019-01-17  Updated: 2019-02-02  Resolved: 2019-02-02

Status: Closed
Project: MariaDB Server
Component/s: Protocol
Affects Version/s: 10.2.21, 10.3.12
Fix Version/s: 10.2.22, 10.3.13

Type: Bug Priority: Major
Reporter: Diego Dupin Assignee: Vladislav Vaintroub
Resolution: Fixed Votes: 2
Labels: None


 Description   

When creating a connection, a connector indicates the charset to use for communication in initial handshake packet.

After a COM_RESET_CONNECTION connection charset is reinitialized not to the one indicated in initial handshake packet, but to another value, character_set_server.

example to reproduced : 

public void test() throws SQLException {
 
    try (Connection connection = DriverManager.getConnection("jdbc:mariadb://localhost:3306/testj?user=root&useResetConnection=true")) {
 
      Statement stmt = connection.createStatement();
 
      showCharacterVariables(stmt);
 
      ((MariaDbConnection)connection).reset();
 
 
 
      showCharacterVariables(stmt);
 
    }
 
  }
 
 
 
  public void showCharacterVariables(Statement stmt) throws SQLException {
 
    ResultSet rs = stmt.executeQuery("SHOW VARIABLES LIKE 'character_%'");
 
    while (rs.next()) {
 
      System.out.println(rs.getString(1) + " " + rs.getString(2));
 
    }
 
    System.out.println("----------------------------------------------");
 
  }

returns :

character_set_client utf8mb4
 
character_set_connection utf8mb4
 
character_set_database latin1
 
character_set_filesystem binary
 
character_set_results utf8mb4
 
character_set_server latin1
 
character_set_system utf8
 
character_sets_dir c:\Program Files\MariaDB 10.2\share\charsets\
 
----------------------------------------------
 
character_set_client latin1
 
character_set_connection latin1
 
character_set_database latin1
 
character_set_filesystem binary
 
character_set_results latin1
 
character_set_server utf8
 
character_set_system utf8
 
character_sets_dir c:\Program Files\MariaDB 10.2\share\charsets\
 
----------------------------------------------

Initial charset transmitted during initial-handshake-packet must be saved and reapplyed, not character_set_server value.
another part that is less important, but resetting connection normally would reset the database to the one set in the same handshake packet

 Comments   
Comment by Sylvain Leroux [ 2019-01-29 ]

I can confirm the problem. I've posted a reproducible use case on StackOverflow before finding this issue:
https://stackoverflow.com/questions/54428189/inconsistent-character-encoding-in-results-when-querying-mariadb-from-node

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