REQUIRED_RETENTION Function

192.1.4 REQUIRED_RETENTION Function

This function returns the required value for the undo_retention parameter to satisfy the longest query based on undo statistics available for a given period.

Syntax

Viewing the output using the historical information in memory:

DBMS_UNDO_ADV.REQUIRED_RETENTION()
RETURN NUMBER;

Viewing the output using start time and end time:

DBMS_UNDO_ADV.REQUIRED_RETENTION(
    start_time IN DATE,
    end_time   IN DATE)
RETURN NUMBER;

Viewing the output using begin and end AWR snapshot ID:

DBMS_UNDO_ADV.REQUIRED_RETENTION(
    begin_snap IN NUMBER,
    end_snap   IN NUMBER)
RETURN NUMBER;

Parameters

Table 192-5 REQUIRED_RETENTION Function Parameters

Parameter	Description
`start_time`	Start time of the given period.
`end_time`	End time of the given period.
`begin_snap`	Begin snapshot identifier. It is based on historical information in AWR from the `begin_snap` identifier.
`end_snap`	End snapshot identifier. It is based on historical information in AWR until the `end_snap` identifier.