GROUP READ LOCK - TARA/ABU

Teradata Archive/Recovery Utility Reference

Product
TARA/ABU
Release Number
16.10
Published
May 2017
Language
English (United States)
Last Update
2018-05-01
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B035-2412
lifecycle
previous
Product Category
Teradata Tools and Utilities

A group read HUT lock can be specified for tables that are defined with an after-image journal option. If the GROUP READ LOCK option is used to perform an online backup of a database-level object, define after-journaling for every table in the database. This restriction also applies to excluded tables; if a table is excluded as part of a database-level GROUP READ LOCK archive, it must still have an after-journal table defined so ARC can accept the GROUP READ LOCK option.

When a group read HUT lock is specified, the following events occur:

  • The AMPs first place an access HUT lock on the entire affected table to prevent users from changing the definition of the table (that is, DDL changes) while the table is being archived.
  • The AMPs then place a series of rolling read HUT locks on blocks of (approximately) 64,000 bytes of table data. Each AMP places a read HUT lock on a block of data while the AMP sends the data block across the IFP or PE to the client.

When a block transmission finishes, the AMP releases the read HUT lock on that block and places another read HUT lock on the next block of 64,000 bytes. The AMPs repeat this process until they archive the entire table.