teras
Просматривал сегодня презентации с сайта "Transaction Processing
Concepts and Techniques" (это курс, который читали в Стенфордском
университете), и в главе
Transaction
Models наткнулся на такое определение:

Nested Transactions.
* A nested transaction is a tree of transactions, the sub-trees of which
are either nested or flat transactions.

* Transactions at the leaf level are flat transactions. The distance
from the root to the leaves can be different for different parts of the
tree.

* The transaction at the root of the tree is called top-level
transaction, the others are called sub-transactions. A transaction's
predecessor in the tree is called parent; a sub-transaction at the next
lower level is also called a child.

* A sub-transaction can either commit or rollback; its commit will not
take effect, though, unless the parent transaction commits.
The rollback of a transaction anywhere in the tree causes all its
sub-transaction to roll back. This combined with the previous point is
the reason why sub-transactions have only ACI, but not D.

Commit rule : The commit of a sub-transaction makes its results
accessible to the parent transaction only. The sub-transaction will
finally commit (i.e. release its results to the outside world) if and
only if it has committed itself locally and all its ancestors up to the
root have finally committed.

Rollback rule : If a (sub-) transaction at any level of nesting is
rolled back, all its sub-transactions are also rolled back, independent
of their local commit status. This is applied recursively down the
nesting hierarchy.

Visibility rule : All changes done by a sub-transaction become
visible to the parent transaction upon the sub-transaction’s commit. All
objects held by a parent transaction can be made accessible to its
sub-transactions. Changes made by a sub-transaction are not visible to
its siblings.

Кстати, обратите внимание, как сформулировано правило видимости.
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Чистой воды дебилизм.

teras
Сахават Юсифов wrote:
>
> Чистой воды дебилизм.

В каком полку служили? ;-)

Кстати, приведу заодно и список дебилов. Во всеобозрение тскзть. А то
им, понимаешь, дают премии Тьюринга за вклад в концепции обработки
транзакций, студентов они учат, а что дебилы никто и не догадывается.

JIM GRAY is a Senior Researcher at Microsoft, working on scalable
computing. He worked on many database and transaction processing systems
at IBM, Tandem, Digital, and Microsoft. With Andreas Reuter, he
co-authored the book Transaction Processing Concepts and Techniques. He
recently received the ACM A.M. Turing Award for his contributions to
transaction processing.

ANDREAS REUTER is the Scientific Director of the European Media
Laboratory (EML) in Heidelberg and Dean of the School of Information
Technology at the International University in Germany at Bruchsal. He
has been an independent consultant, a Professor at Kaiserslautern and at
Stuttgart where he founded the Institute of Parallel and Distributed
High Performance Systems. He was Computer Science Dean and later
Vice-President of Stuttgart University.

PHIL BERNSTEIN is a senior researcher in the Microsoft Research Database
Group and an architect of the Microsoft Repository. His research is in
the areas of databases, particularly on repository systems (object
databases, information models, version and configuration management) and
transaction processing (concurrency control and recovery). He coauthored
the books Principles of Transaction Processing and Concurrency Control
and Recovery in Database Systems, and teaches at U. Washington.

DIETER GAWLICK is an architect in Oracle's Database Server development
team. He focuses on extending the database technology to support
messaging and EAI (Enterprise Application Integration).Before joining
Oracle, Dieter developed a workflow system at Digital, and worked on
high performance I/O technology at Amdahl.During his time at IBM, Dieter
developed OLTP and database technology with the focus on high
performance and high availability. Dieter is the inventor and architect
of IBM's IMS Fast Path

DAN HARKEY along with Robert Orfali and Jeri Edwards, is co-author of
the best-selling books,Client/Server Survival Guide and Client/Server
Programming with Java and CORBA.Dan also heads the CORBA/Java
distributed objects master's program and lab at San Jose State
University and is a distributed objects consultant for IBM.

GREG HOPE is an architect at Microsoft working on the COM+, MTS, and DTC
technologies (http://www.microsoft.com/com). Prior to joining
Microsoft's "viper" project, Greg built a variety of distributed OLTP
systems, including co-founding Prologic in 1984, and implementing PROBE
and Ovation, a PC based (MS-DOS / Windows NT) distributed TP monitor and
retail banking system in production at over 300 banks in 20 countries
(http://www.prologiccorp.com).

CHARLES LEVINE is a Program Manager in the SQL Server Performance Group
at Microsoft, focused on benchmark and ISV performance issues. Charles
has been active in the Transaction Processing Performance Council (TPC)
since 1989, contributing to the definitions of TPC-A, B, and C. For the
last four years, Charles has served as Chairman of the TPC.

C. MOHAN joined IBM Research in 1981. He was named an IBM Fellow in 1997
for contributions to transaction management. He is an IBM Master
Inventor with 32 patents. His research results are implemented in
numerous IBM and non-IBM products. He is the primary inventor of the
ARIES family of recovery and locking methods, and the industry-standard
Presumed Abort commit protocol.

SUSAN MALAIKA is a senior software engineer at IBM's Santa Teresa DB2
development group. She specializes in distributed DB2, stored
procedures, XML and the Web. Before joining DB2 in 1997, Susan was an
Internet specialist in the UK and initiated projects that provide Web
access to IBM systems. Susan also worked in the CICS transaction
processing development group in the area of recovery, long running
transactions, interfaces to database management systems, and distributed
applications.
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Да глубоко наплевать кто они там.
Вложенные транзакции и дерево транзакций - фигня. Это уже не транзакции а синхронизаторы.