How do I set up an undo retention guarantee?

How do I set up an undo retention guarantee?

Setting the 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;

How do I calculate the size of my undo tablespace?

Size your Undo tablespace

1. Step 1: Longest running query. SQL> select max(maxquerylen) from v$undostat; MAX(MAXQUERYLEN)
2. Step 2: Size of UNDO tablespace. Size of UNDO needed = UNDO_RETENTION x [UNDO block Generation per sec x DB_BLOCK_SIZE] + Overhead(30xDB_BLOCK_SIZE)

What is Oracle rollback segment?

Rollback segments were database structures used to track undo information for the database in earlier releases of Oracle Database. Now, the preferred way of managing undo information is with the undo tablespace. For more information, see “Managing Undo Data”.

What is undo in Oracle?

Oracle Database creates and manages information that is used to roll back, or undo, changes to the database. Such information consists of records of the actions of transactions, primarily before they are committed. These records are collectively referred to as undo.

How do I limit the amount of undo space in Oracle?

The Oracle Database Resource Manager can be used to establish user quotas for undo space. The Database Resource Manager directive UNDO_POOL allows DBAs to limit the amount of undo space consumed by a group of users (resource consumer group). You can specify an undo pool for each consumer group.

What is the undo_tablespace parameter used for?

The UNDO_TABLESPACE parameter can be used to assign a specific undo tablespace to an instance in an Oracle Real Application Clusters environment. The database can also run in manual undo management mode. In this mode, undo space is managed through rollback segments, and no undo tablespace is used. Space management for rollback segments is complex.

What are the initialization parameters for undo management?

The following is a summary of the initialization parameters for undo management: If AUTO or null, enables automatic undo management. If MANUAL, sets manual undo management mode. The default is AUTO. Optional, and valid only in automatic undo management mode.

Can I use the pending undo tablespace of another instance?

A PENDING OFFLINE undo tablespace cannot be used by another instance, nor can it be dropped. Eventually, after all active transactions have committed, the undo tablespace automatically goes from the PENDING OFFLINE mode to the OFFLINE mode.