Oracle Management 7

Revocation Management

What is undo data:

1. Transaction fallback: No transaction submitted can be rollback

2. Transaction recovery: When the database crashes, the incorrect data of the disk is restored to the pre-transaction

3. Read consistency: The queried record has a transaction occupation, to the rollback segment to find the pre-change mirror

4. Flashback data: Constructing historical data from a rollback segment

Transaction and Revocation data:

Redo and Undo:

AUM:

3 parameters, two table space properties

Undo_management=auto the Segment management mode of the rollback table space segment, the administrator only needs to have sufficient tablespace capacity, and Oracle automatically manages the number of extended rollback segments. Only one undo table space can be used.

Undo_tablespace: can only be used in automatic management mode. Indicates which undo table space to use

undo_retention=900: The unit is: seconds

The time that the old mirror remains in the rollback segment after the commit. Extra time to be retained after submission

The non-mandatory fallback hold time. (The old image will be overwritten if the rollback space is not enough)

Autoextend: Table Space Auto-expansion

Mandatory maintenance: But the space requirements are large, should be used with caution. (10g start support)

Alter Tablespace UNDOTABS1 RETENTION GUARANTEE;

Select Tablespace_name,retention from Dba_tablespaces;

Undo_retention specifies (in seconds) how long already committed undo information was to be retained. The only time of must set this parameter are when:

? The undo Tablespace has the autoextend option enabled

? You want to set undo retention for LOBs

? You want to guarantee retention

Undo Advisor:

Scheduling jobs

$ PS-EF | grep CJQ

Sql> Show Parameter job_queue_processes

Background pre-set automation management jobs:

Custom job:

Sql> CREATE TABLE Session_history (snap_time timestamp with local time zone, num_session number);

Create Job in EM:

Using Plsql blocks:

Declare

Session_count number;

Begin

Select COUNT (*) into Session_count from V$session;

INSERT into session_history values (Systimestamp, session_count);

Commit

End

Global support

$ VI. bash_profile

#export Nls_lang=american_america. Al32utf8

#export nls_date_format= ' Yyyy-mm-dd hh24:mi:ss '

$ unset Nls_lang

$ unset Nls_date_format

Sql> select Sysdate from dual;

Oracle Management 7