Enq: DM-contention wait event when resetlogs opens the database

In recent cases, the database and alterdatabaseopenresetlogs commands under 10.2.0.5.12 have been waiting. The alert_sid.log information is: settingrecoverytargetincarnationto2. The waiting event obtained from v $ session. event is enq: DM.

In recent cases, the alter database open resetlogs command in db 10.2.0.5.12 has been waiting. The alert_sid.log information is: setting recovery target incarnation to 2 from v $ session. the wait event obtained by the event is enq: DM-contention from select KSQSTTYP, KSQSTEXPL from x $ ksqst

In recent cases, the alter database open resetlogs command in db 10.2.0.5.12 has been waiting, and the alert_sid.log information is:

Setting recovery target incarnation to 2

The waiting event obtained from v $ session. event is enq: DM-contention.

From select KSQSTTYP, KSQSTEXPL from x $ ksqst where KSQSTTYP = 'dm', we can see that the waiting event is interpreted:

Enqueue held by foreground or DBWR to syncrhonize database mount/open [from Internet of Hong (http://www.68idc.cn)] with other operations