MDEV-23283 User Statistics does not correctly reflect concurrent_conn…

[DaveGosselin-MariaDB]

…ections

Keep concurrent_connections updated when user stats are enabled. When a user connects, the count in concurrent_connections increases by one; when they disconnect, it decreases by one.

Setting the global userstat begins counting new concurrent sessions from that point forward; pre-existing concurrent sessions are not counted until they are restarted. Ideally this configuration is set in the my.cnf file so as to apply from server startup, ensuring that the counter is consistent. If it is set during the server's lifetime (via SET GLOBAL userstat=1) it is recommended to do so before concurrent user sessions exist for accurate counts.

[vuvova]

generally, ok, but see comments and questions below

[vuvova]

does it change? how?

also, don't say "commit bead24b" because it's in a much later branch. I'd just say "because the previous commit", presuming you've put the cherry-pick in a separate commit

[DaveGosselin-MariaDB]

It increases the bytes_received count by 14:

--- /home/code/5-server/mysql-test/main/userstat-badlogin-4824.result	2025-09-09 00:31:50.920752336 -0400
+++ /home/code/5-server/mysql-test/main/userstat-badlogin-4824.reject	2025-09-09 11:04:48.198199839 -0400
@@ -10,13 +10,13 @@
 connection default;
 select user, bytes_received from information_schema.user_statistics where user = 'foo';
 user	bytes_received
-foo	18
+foo	32
 connect(localhost,foo,bar,test,MASTER_PORT,MASTER_SOCKET);
 connect foo, localhost, foo, bar, test;
 ERROR 28000: Access denied for user 'foo'@'localhost' (using password: YES)
 connection default;
 select user, bytes_received from information_schema.user_statistics where user = 'foo';
 user	bytes_received
-foo	18
+foo	32
 drop user foo@localhost;
 set global userstat=@save_userstat;