1. Am avut azi o discutie cu George Pristavu DPE Lead la Microsoft Romania (pentru cine nu stie George vine de la Oracle) si mi-a spus ca e posibil sa se discute despre tehnologia
Flashback Flashback Transaction
Large-scale database applications rely on
complex sequences of transactions, to ensure atomicity and consistency
of a group of inserts, updates, or deletes. In the event of a ‘bad’
transaction, the administrator must trail back-in-time to see what
changes were effected by the transaction and ascertain any dependencies
(e.g. transactions that modified the same data after the ‘bad’
transaction), to ensure that undoing the transaction preserves the
original, good state of the data and any related data. Performing this
type of transaction analysis can be laborious, especially for very
complex applications.
With Flashback Transaction, a single transaction,
and optionally, all of its dependent transactions, can be flashed back
with a single PL/SQL operation or by using an intuitive EM wizard to
identify and flashback the problem transactions. Flashback Transaction
relies on the availability of undo data and archived redo logs for the
given transaction and its dependents, to backout the changes.
The
Oracle Database architecture leverages the unique
technological advances in the area of database recovery due
to human errors. Oracle Flashback Technology provides a set
of new features to view and rewind data back and forth in
time. The Flashback features offer the capability to query historical data, perform
change analysis, and perform self-service repair to recover
from logical corruptions while the database is online. With
Oracle Flashback Technology, you can
indeed undo the past!
Oracle9i introduced Flashback Query to provide a
simple, powerful and completely non-disruptive mechanism for
recovering from human errors. It allows users to view the
state of data at a point in time in the past without requiring
any structural changes to the database.
Oracle Database 10g extended the Flashback Technology to provide fast and
easy recovery at the database, table, row, and transaction
level. Flashback Technology revolutionizes recovery by operating
just on the changed data. The time it takes to recover the
error is now equal to the same amount of time it took to make
the mistake. Oracle 10g Flashback Technologies includes
Flashback Database, Flashback Table, Flashback Drop, Flashback
Versions Query, and Flashback Transaction Query.
Flashback
technology can just as easily be utilized for non-repair purposes, such
as historical auditing with Flashback Query and undoing test changes
with Flashback Database. Oracle Database 11g introduces an innovative
method to manage and query long-term historical data with Flashback
Data Archive. This release also provides an easy, one-step transaction
backout operation, with the new Flashback Transaction capability.
In SQL Server se pot obtine functionalitati aproximativ similare prin Database Snapshots si Point in Time Revovery (restaurare de transaction log). Functionalitate similara insa nu identica.
Cristian Andrei Lefter, SQL Server MVP
MCT, MCSA, MCDBA, MCAD, MCSD .NET,
MCTS, MCITP - Database Administrator SQL Server 2005
http://sqlserver.ro