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[] =
|
{
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{ STRING_WITH_LEN("Error") }, // cannot happen
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{ STRING_WITH_LEN("TCP/IP") },
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{ STRING_WITH_LEN("Socket") },
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{ STRING_WITH_LEN("Named Pipe") },
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{ STRING_WITH_LEN("SSL/TLS") },
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{ STRING_WITH_LEN("Shared Memory") }
|
};
|
Yet it actually indeed shows "Error" instead of "NULL":
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 |
|
+-----------------------------------+-----------------+
|
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Bug
Major
versions older than 10.5 are not affected as the column was first added there
I also tested the first 10.5 GA, it has been "Error" instead of NULL from the very beginning