Setting Redrive Protection for Users, Accounts, and Profiles - Teradata Database

Setting Redrive Protection for Users, Accounts, and Profiles

You can enable or disable Redrive protection for individual users, accounts, and profiles using the TDWM.Redrive table:

1 Ensure that TASM is running.

2 Insert, modify, or delete rows in TDWM.Redrive to specify whether particular users, accounts, or profiles will participate in Redrive.

3 From the Teradata Viewpoint Workload Designer portlet, issue the TDWM Activate command after changing the TDWM.Redrive table in order for the new changes to take effect.

The table definition for TDWM.Redrive is:

CREATE SET TABLE TDWM.Redrive ,FALLBACK ,

     NO BEFORE JOURNAL,

     NO AFTER JOURNAL,

     CHECKSUM = DEFAULT,

     DEFAULT MERGEBLOCKRATIO

     (

      ObjectType VARCHAR(10) CHARACTER SET UNICODE 

                 NOT CASESPECIFIC NOT NULL,

      ObjectName VARCHAR(128) CHARACTER SET UNICODE 

                 NOT CASESPECIFIC NOT NULL,

      RedriveMethod INTEGER NOT NULL)

UNIQUE PRIMARY INDEX ( ObjectType ,ObjectName );

Insert a row into the table or modify an existing row in the table to specify whether Redrive protection is enabled for a particular user, account, or profile:

Column Name	Valid Values	Description
ObjectType	In order of precedence, where USER is most specific and PROFIL is least specific: USER ACCT (account) ACCTSTR (account string) PROFIL (profile)	Specifies whether you are setting Redrive protection for a user, an account, or a profile.
ObjectName	The name of the object	The name of the user (or application), account, or profile for which you are setting Redrive protection. For example, if ObjectType is USER, then ObjectName is the user name.
RedriveMethod	1 (Disable Redrive) 2 (Enable Redrive)	Determines whether Redrive is enabled or disabled for the user, account, or profile specified by ObjectName.

When there is a conflict, the most specific ObjectType is used. For example, suppose these rows are in TDWM.Redrive:

ObjectType	ObjectName	RedriveMethod
USER	Mark	1
PROFIL	Manager	2

If a session logs on as USER Mark and PROFIL Manager, since both rows in the table qualify, the most specific ObjectType is chosen. USER is more specific than PROFIL; therefore, RedriveMethod 1 (Do not use Redrive) is chosen and the session will not participate in Redrive.

If there is no row in TDWM.Redrive for the session, the RedriveDefaultParticipation DBS Control field determines whether the session participates in Redrive.

Redrive attributes are assigned to users, accounts, and profiles at logon time, and these attributes remain for the entire session. The attributes are not changed for that session even if new entries are made to TDWM.Redrive that would apply to the session. However, once Redrive is enabled, you can use the Redrive query band to turn Redrive off and on during the life of the session.

 

Restrictions

Redrive only hides database restarts from requests running in the SQL partition.

If a UDF or external stored procedure modifies data that is external to Teradata Database, then the request involving that function or procedure cannot be redriven.

If a database restart occurs while SELECT AND CONSUME requests are waiting for rows to consume, the restart is hidden from the application, but the queued up requests will not be in the same order as they were at the time of the restart.

If a PE node fails, then the restart cannot be hidden from applications that were logged onto the failing node.

Database restarts cannot be hidden if the restart occurs:

During execution of stored procedures.

After the first request of an explicit Teradata transaction or an ANSI/ISO transaction and the transaction placed a write lock or exclusive lock on a table in database DBC.

After the request is committed on the AMPs but before the PE is notified of the commit.

Example  

When the session logs on and you have these settings...	Then the session...
RedriveProtection DBS Control field is 0	will not participate in Redrive.
RedriveProtection DBS Control field is 1 Redrive field in Session Options parcel is 'Y' TDWM.Redrive contains a row matching your user name, account, account string, or profile with RedriveMethod = 1 (Do not use Redrive)	will not participate in Redrive because the row in TDWM.Redrive specifies not to use Redrive.
RedriveProtection DBS Control field is 1 Redrive field in Session Options parcel is 'N' TDWM.Redrive contains a row matching your user name, account, account string, or profile with RedriveMethod = 2 (Use Redrive)	will not participate in Redrive because the Redrive field in the Session Options parcel is 'N'.
RedriveProtection DBS Control field is 1 Redrive field in Session Options parcel is 'Y' TDWM.Redrive does not contain any matching row or it contains a row matching your user name, account, account string, or profile with RedriveMethod = 2 (Use Redrive)	will participate in Redrive.

Example  

If you want to use Redrive, but do not want to change any application settings:

If you only want a single account to use Redrive:

a Set the RedriveProtection DBS Control field to 1.

b Set the RedriveDefaultParticipation DBS Control field to 0.

c Add a row in TDWM.Redrive for the account and enter a value of 2 in the RedriveMethod column for the account.

If you want all sessions to use Redrive except those from a particular account string:

a Set the RedriveProtection DBS Control field to 1.

b Set the RedriveDefaultParticipation DBS Control field to 1.

c Add a row in TDWM.Redrive for the account string and enter a value of 1 in the RedriveMethod column for the account string.

Related Topics

For information on...	See...
the RedriveProtection and RedriveDefaultParticipation DBS Control fields	Utilities
using the REDRIVE query band to enable or disable Redrive protection for a session	SQL Data Definition Language Detailed Topics