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Teradata RDBMS Database Administration - NCR

NCR Teradata RDBMS Database Administration - NCR , 2004. - 616 p.
Download (direct link): teradatadatabaseadmin2004.pdf
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Requirements and restrictions include the following:

The backup must be an all-AMP or cluster-level archive.

You cannot dump the DBC database with GROUP READ LOCK.

The table must have after-image journal and the journal must be archived to complete the backup.

The ARC utility places a read lock on tables during archive operations that prevents users from updating a table during the process. The dump must be complete and the lock released before processing resumes to the table.

You can use the keyword GROUP with READ LOCK to circumvent this limitation. With GROUP, the read lock is placed at the row level, as follows:

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Teradata RDBMS Database Administration 8 - 19 Chapter 8: Archiving, Restoring and Recovering Data

Archive Routines (Recommended)

Step Process
1 The utility places an access lock on the entire table.
2 A group of table rows (about 32,000 bytes) are locked for read.
3 The locked rows are archived.
4 The lock is released on that group of rows.
5 Another group of rows is locked.

The access lock prevents anyone from placing an exclusive lock on the data table while the archive is in process. By placing a read lock which disables writings on a small group of rows within the table, users can continue to make updates directly to the rows not being archived.

In the event that someone attempts to update a row that is under a read lock, the change is written to the after-image journal but the data row remains unchanged. The after-image journal must be backed up to have a complete archive of all data.

Types of Archives

The following types of archives back up data on removable media. The information in the archive file depends on the archive type, the table protection used, and your Teradata configuration.

Note: You can fully restore database DBC only to an empty Teradata RDBMS.

Archive Type Table Protection Type Data Included
All AMP database Fallback Primary data rows and Secondary Indexes (SIs) from all the tables in the database(s) Data Dictionary rows of the tables / macros/views / stored procedures All table/macro/view/stored procedure information Table structure information
No fallback Available data rows Data Dictionary rows of the tables/macros/views/stored procedures All table/macro/ view / stored procedures information Table structure information Note that no secondary indexes are included if the AMP is down.

Teradata RDBMS Database Administration

8 - 19 Chapter 8: Archiving, Restoring and Recovering Data

Archive Routines (Recommended)

Archive Type Table Protection Type Data Included
All AMP table Fallback Primary data rows Secondary Indexes (SIs) All dictionary information for the table All table, column, and index definitions
No fallback Available data rows All dictionary information for the table All table, column, and index definitions Note that no SIs are included if the AMP is down.
Specific AMP No fallback Available data rows from the table(s) within the database(s) Table structure information Note that: No dictionary rows are included. This information is included in the Dictionary dump. No SIs are included.
Specific cluster Fallback or no fallback Available data rows from the table(s) within the database(s) Table structure information Note that: No dictionary rows are included. This information is included in the Dictionary dump. No SIs are included.
Data Dictionary Dictionary rows for tables/macros/views. For tables: DBC.TVM DBC.TVFields DBC.Indexes DBC.IndexNames Note that PJ information is not included.

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Teradata RDBMS Database Administration 8 - 19 Chapter 8: Archiving, Restoring and Recovering Data

Archive Routines (Recommended)

Archiving the Data Dictionary

The Data Dictionary tables are maintained in the default database associated with system user DBC. This means that as they grow, they consume DBC PERM space, space also required by the TJ and other internal recovery journals. To protect your system software, you should archive the DBC database when:

A high volume of DDL statements has significantly increased the quantity of definitions for data tables, views, macros, indexes, triggers, stored procedures, roles, and/or profiles since your last DBC archive.

You plan to purge some dictionary logs that have grown very large due to a high volume of recorded activities, queries, or statistics.

You plan to upgrade your Teradata RDBMS or migrate to a different server platform.

Some dictionary tables, such as DBQLRuleTbl, are not archived automatically. If you want to retain the contents through a migration, (which requires a system initialization), you might need to recreate the rows. To do this fairly simply:

Maintain all statements that control rules, for example BEGIN/END QUERY LOGGING, in a BTEQ executable (script) file.

After the migration has completed (and after the DIP utility and the ARC Restore of data and dictionary tables have been run), execute the BTEQ script to recreate the contents of the table.
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