[MXS-4062] Got strange warning messages | Warning: Unknown prepared statement handler (590935) given to MaxScale for COM_STMT_CLOSE by ''user'@'::ffff:192.x.x.x'' Created: 2022-03-24  Updated: 2023-02-08  Resolved: 2022-06-20

Status: Closed
Project: MariaDB MaxScale
Component/s: maxbase
Affects Version/s: 6.2.3
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Pon Suresh Pandian (Inactive) Assignee: markus makela
Resolution: Incomplete Votes: 2
Labels: None
Environment:

Ubuntu 20.04

Maxscale 6.2.3

Attachments: Text File maxscale_2022-03-24.log    
Issue Links:
Relates
relates to MXS-4429 Many "Unknown prepared statement hand... Closed
Sprint: MXS-SPRINT-154, MXS-SPRINT-155, MXS-SPRINT-156, MXS-SPRINT-157, MXS-SPRINT-158, MXS-SPRINT-159, MXS-SPRINT-160

 Description   

Hi Team,

We got strange warning messages from maxscale logs.

2022-03-23 18:13:04   warning: (116) (worker_1); Unknown prepared statement handler (100922) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''
 
2022-03-23 18:13:05   warning: (116) (worker_1); Unknown prepared statement handler (100981) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''
 
2022-03-23 18:13:05   warning: (116) (worker_1); Unknown prepared statement handler (100991) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''
 
2022-03-23 18:13:05   warning: (116) (worker_1); Unknown prepared statement handler (100093) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''
 
2022-03-23 18:16:41   warning: (233) (worker_1); Unknown prepared statement handler (767988) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''
 
2022-03-23 18:16:42   warning: (233) (worker_1); Unknown prepared statement handler (768020) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''
 
2022-03-23 18:16:42   warning: (233) (worker_1); Unknown prepared statement handler (767827) given to MaxScale for COM_STMT_CLOSE by ''user1'@'::ffff:192.xx.x.x''

Here I have attached the maxscale logs for your reference please check it.

 Comments   
Comment by markus makela [ 2022-07-07 ]

Ran into one case where this might be possible: if an application opens up more prepared statements than the size of max_sescmd_history can contain, it is possible that under certain circumstances (e.g. with lazy_connect=true) some prepared statements end up not being executed as they have fallen outside of the stored history range.

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