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Database appears very high enq: DX-contention waiting for how to solve, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can gain something.

When examining the customer AWR report, it was found that the database experienced a severe enq: DX-contention wait.

The version of this database is 11.1.0.6 for Windows 64bits for AMD, and in the AWR report, the TOP 5 wait event is:

Event

Waits

Time (s)

Avg wait (ms)

% DB time

Wait Class

Enq: DX-contention

22627

135751

6000

126.41

Other

Inactive transaction branch

22625

22626

one thousand

21.07

Other

Db file scattered read

1312470

4212

three

3.92

User I/O

DB CPU

3928

3.66

Db file sequential read

1349206

3522

three

3.28

User I/O

Among them, the waiting of enq: DX-contention is the most serious, which is actually inactive transaction branch. The average waiting time of these two waiting events is 6 seconds and 1 second respectively, and it is obviously no accident that the average waiting time is so whole, which shows that the two waiting times have experienced their own timeout.

Query metalink, which is also caused by BUG, and this error is described in the document High CPU by Sessions Holding DX Enqueue; Others Waiting 'enq: DX-contention' [ID 1275884.1].

The cause of the problem is that some users with distributed transaction queues try to abort or exit distributed transactions, and Oracle takes up a lot of CPU resources when processing.

The flag used to determine whether this problem occurs is that there are obvious enq: DX-contention and inactive transaction branch wait events in the database.

This issue affects versions 10.2 and 11.1, which was FIXED in 11.2. This problem can be solved by making a separate patch of 8552942.

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