[#MDEV-28255] "Error" instead of NULL in P_S.THREADS_CONNECTION

According to the KB the P_S.THREADS.CONNECTION_TYPE column should show NULL for background threads, and the source code has these possible states:

static const LEX_CSTRING vio_type_names[] =

  { STRING_WITH_LEN("Error") }, // cannot happen

  { STRING_WITH_LEN("TCP/IP") },

  { STRING_WITH_LEN("Socket") },

  { STRING_WITH_LEN("Named Pipe") },

  { STRING_WITH_LEN("SSL/TLS") },

  { STRING_WITH_LEN("Shared Memory") }

};

MariaDB [performance_schema]> select name, connection_type from threads where type="BACKGROUND";

+-----------------------------------+-----------------+

| name                              | connection_type |

+-----------------------------------+-----------------+

| thread/sql/main                   | Error           |

| thread/mysys/statement_timer      | Error           |

| thread/aria/checkpoint_background | Error           |

| thread/innodb/page_cleaner_thread | Error           |

| thread/innodb/thread_pool_thread  | Error           |

| thread/innodb/thread_pool_thread  | Error           |

| thread/innodb/thread_pool_thread  | Error           |

| thread/innodb/thread_pool_thread  | Error           |

| thread/innodb/thread_pool_thread  | Error           |

| thread/innodb/thread_pool_thread  | Error           |

| thread/sql/signal_handler         | Error           |

| thread/sql/manager                | Error           |

+-----------------------------------+-----------------+

[MDEV-28255] "Error" instead of NULL in P_S.THREADS_CONNECTION_TYPE for background threads Created: 2022-04-07 Updated: 2022-04-09 Resolved: 2022-04-09
Status:	Closed
Project:	MariaDB Server
Component/s:	Performance Schema
Affects Version/s:	10.5.15, 10.6.7, 10.7.3, 10.8.2
Fix Version/s:	10.5.16, 10.6.8, 10.7.4