Oracle region Management

This article was slightly modified by the gototop root baiyufeng article. Http://www.ncn.cn/
Oracle zookeeper has the following modes:
0: None
1: NULL
2: Row-s row sharing (RS): Shared table partition, sub share
3: Row-x row percentage (RX): used for row modification, sub exclusive
4: Share share (s): block other DML operations, share
5: S/row-x shared row percentage (SRx): block other business operations, share/sub exclusive
6: exclusive shares (x): used by the independent users, exclusive

The larger the number, the higher the number of Shadow operations.

1 rows: Select, sometimes v $ locked_object appears.
2 distinct rows: Select for update, lock for update, lock row share
When the select for update clause is used to open a game with the for update substring, all the data rows in the returned set will be processed in row-X (Row-x) depends depends on the formula. Other objects can only query these data rows, but cannot perform update, delete, or select for update operations.
3 distinct rows: insert, update, delete, lock row exclusive
No such record is inserted before the commit operation. There is no response, because the last 3 record will be waiting for the last 3 record, we must release the previous job to renew the job.
4 zookeeper: Create index, lock share
Locked_mode is 2, 3, 4 does not affect the commit DML (insert, delete, update, select) operation, but the DDL (alter, drop, etc.) operation will prompt the ora-00054 commit failure.
00054,000 00, "resource busy and acquire with Nowait specified"
// * Cause: Resource interested is busy.
// * Action: retry if necessary.
5. Multiple tables: Lock share row exclusive
In some cases, update/delete may occur when there is an external primary node...; may generate 4 or 5 rows.
6 partition tables: alter table, drop table, drop index, truncate table, lock exclusive

You can use the following SQL statement to view the information about the current database metadata using the DBA role:

Col owner for A12
Col object_name for A16
Select B. Owner, B. object_name, L. session_id, L. locked_mode
From v $ locked_object L, dba_objects B
Where B. object_id = L. object_id
/

Select t2.username, t2.sid, t2.serial #, t2.logon _ time
From v $ locked_object T1, V $ session T2
Where t1.session _ id = t2.sid order by t2.logon _ time
/

If a column appears for a long time, it may be that there is no limit. We can use the following SQL statement to explain whether there are abnormal errors in the long term:

Alter system kill session 'sid, serial #';

If a problem occurs, a DML operation may wait for a long time for no response.

When you use the direct data access method, do not run the $ kill process_num or $ kill-9 process_num command on the OS system to stop using the Failover method, because a pipeline may generate more than one pipeline, the sequence of the operating system cannot be cleared.