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What is Oracle undo retention?

What is Oracle undo retention?

When automatic undo management is enabled, there is always a current undo retention period, which is the minimum amount of time that Oracle Database attempts to retain old undo information before overwriting it.

What is default undo retention period in Oracle 10g?

300 seconds
The default is 300 seconds (5 minutes), and you can set this parameter to guarantee that Oracle keeps undo logs for extended periods of time. Rather than having to define and manage rollback segments, you can simply define an Undo tablespace and let Oracle take care of the rest.

What is undo tablespace in Oracle 11g?

Undo tablespace is a kind of permanent tablespace used by oracle database engine to manage undo data if you are running your database in automatic undo management mode. This undo data or undo records are generally used to: Roll back transactions when a ROLLBACK statement is issued. Recover the database.

What is undo Advisor in Oracle 11g?

The Undo Advisor assists in correctly sizing the undo tablespace and to set the low threshold value of the undo retention period for any Oracle Flashback requirements. See Oracle Database Performance Tuning Guide for more information.

How do I undo a retention?

Setting the Minimum Undo Retention Period

  1. Set UNDO_RETENTION in the initialization parameter file. UNDO_RETENTION = 1800.
  2. Change UNDO_RETENTION at any time using the ALTER SYSTEM statement: ALTER SYSTEM SET UNDO_RETENTION = 2400;

What is optimal undo retention?

With UNDO_RETENTION parameter, automatic undo management allows to specify how long undo information must be retained after commit. The default value of this parameter is 900s.

How do I change undo retention?

Who is using undo tablespace Oracle?

Find session who generating lot of undo in Oracle

  1. Find the session using more undo tablespace. select a.sid, a.serial#, a.username, b.used_urec used_undo_record, b.used_ublk used_undo_blocks.
  2. Check the SQL TEXT using or generating undo segments.
  3. Check the undo usage by session.

How do I calculate the size of my undo tablespace?

All you need to do is create an undo tablespace and set UNDO_MANAGEMENT = AUTO. You can choose to allocate a specific size for the UNDO tablespace and then set the UNDO_RETENTION parameter to an optimal value according to the UNDO size and the database activity.

How do I get rid of undo tablespace?

How to shrink Oracle database “undo” tablespace data file?

  1. Check which file is used for undo tablespace.
  2. Create new undo tablespace.
  3. Tell the system to use new undo tablespace from current point of time.
  4. Restart database instance.
  5. Check if all related old undo tablespace segments went OFFLINE:

What does Oracle Database 11 G Release 2 do?

Oracle Database 11 g Release 2 brings a whole new connection type to the already available shared and dedicated modes. Created specifically with Web traffic in mind, database resident connection pooling (DRCP) uses a combination of dedicated server and connection broker to handle short, transient sessions coming from Web applications.

What’s the difference between Oracle 11g and Oracle 11i?

Oracle 11G is a version of oracle database, and “G” stands for grid. Oracle Applications is a separate product , just like any other applications specifically ERP’s where as Oracle database is an Industry standard database, that stores and retrieves relational data.

When does extended support end for Oracle 11gR2?

We previously waived Extended Support fees for the first year of Extended Support, so up until 31st January 2016. We have now further extended the fee waiver period until 31 Dec 2018. Extended Support fees are now liable beginning Jan 1, 2019. Extended Support Originally, Extended Support for 11gR2 was due to terminate on 31st January 2018.

How much storage does Oracle Database 11 g Xe have?

With respect to growing needs for storage, Oracle Database 11 g XE now offers a full 11GB for user data alone, which is almost threefold increase since previous 4GB limit in Oracle Database 10 g XE. Other hardware restrictions remain the same with CPU usage capped at one physical core and memory at 1GB.