Kittiphan Techakittiroj (09/05/58 10:21 น. 09/05/58 10:21 น. 09/05/58 10:21 น.) Transaction Processing Kittiphan Techakittiroj [email protected]

Kittiphan Techakittiroj (21 . . 2566เม ย )

Transaction Processing

Kittiphan Techakittiroj

[email protected]


• Introduction to Transaction and ACID

• Transacion Models

• TP Monitors

• TP-lite & TP-heavy

Agenda


Transaction Processing• Set of commands to process at once

– Faster processing

– Reduce the complexity of works

• Easy example: saving a file not a character


Transaction Processing cont.

• Big organization: do many things for one operation,

e.g. check # of employee, assigned the salary, calculate

the tax and make a payment

• Banking is one example: check clearing


ACIDProperties of Transaction

• Atomicity: all operations as one item … either succ

ess all or fail all

• Consistency:– correct, accurate, and valid

– if the transaction is not success, server return to stable state

• Isolation: not disturb with other transaction

• Durability: after commit, the changes should be per

manent (not effect by any failure)


Transaction Models

• Describe the way a transaction can be proce

ssed

• Should be general enough for any kinds of t

ranasaction

• Make transactions accomplish the ACID pr

operties


• Flat Transaction

– Baby Stepping With Flat Transactions

– Distributed Flat Transaction

• Chained Transactions

• Nested Transactions

ModelsTransaction Models


• Contain three steps:

– Begin Transaction

– Process Transaction

– End Transaction

• Success: commit

• Failure: abort + rollback

Flat TransactionTransaction Models: Models


Flat Transaction

• Contain three steps:

– Begin Transaction

– Process Transaction

– End Transaction

• Success: commit

• Failure: abort + rollback

Flat Transaction Providing ACID

Transaction Models: Models: Flat Transaction

ACID

• Atomicity

• Consistency

• Isolation

• Durability


• Eliminate the problems of Flat Transaction:

– holding resource for too long

– if abort, the whole works are gone

• Separate the transaction to be small transactions

Baby Stepping with Flat TransactionTransaction Models: Models: Flat Transaction


• Extend the Flat Transaction to multiple-site

systems

• Need the synchronization between each site

Distributed Flat TransactionTransaction Models: Models: Flat Transaction


• synchronization for Distributed Flat Transaction

• Consider two types of systems

– commit manager node or root node or transaction

coordinator

– subordinate nodes

• Two main phases:

– Ask everyone to be ready to commit

– Ask every one to commit

Two Phase Commit ProtocolTransaction Models: Models: Flat Transaction: Distributed Flat Transaction


• First Phase

– commit manager sends “prepare-to-commit”

– commit manager wait for “ready-to-commit”

– first phase finish when all nodes is “ready-to-commit”

Two Phase Commit Protocol cont.

Transaction Models: Models: Flat Transaction: Distributed Flat Transaction


• Second Phase

– commit manager send

“commit”

– commit ended:

• all nodes complete

“commit”

• negative response from

any node make commit

manager order

“rollback” to every

nodes

Two Phase Commit Protocol cont.

Transaction Models: Models: Flat Transaction: Distributed Flat Transaction


• transactions that need to be partially rooled back

• transactions with humans in the loop: causes the hold

of resources for long period (something might also happens

on the way, e.g. GUI cracked)

LimitationsTransaction Models: Models: Flat Transaction


• transaction with long time update

• large transaction: e.g. updates of million records

• transaction across companies or the Internet: political

and privacy issues

Limitations cont.

Transaction Models: Models: Flat Transaction


• chaining many transaction together

• three common patterns:

– syncpoints

– chained transactions

– sagas

Chained TransactionTransaction Models: Models:


• Make synchronization points in-between transaction

• Allow the rollback at each synchronization point

• not durable to the system crash

SyncpointsTransaction Models: Models: Chained Transaction


• make the synchronization points become “commit”

• create “durability”

• lost “atomic”: the ability to roll-back entired transaction

Chained TransactionTransaction Models: Models: Chained Transaction


• same as normal chained transactions but allow the r

oll-back for the entire transaction

• this create the “atomic”

• need to keep track the entired process of transaction

SagasTransaction Models: Models: Chained Transaction


• allow transactions inside a transaction

• hierarchies of “subtransactions”

Nested TransactionTransaction Models: Models:


TP Monitors

• process management: start server process, monitor

process

• transaction management: queuing, transaction

scheduling, prioritization service

• communications management between clients

and the server


TP Monitors cont.


• the management over OS

• two mains functions

– pass the client request to server

– load balancing

FunnelingTP Monitor


• load balancing:

– create process if necessary

– destroy process if possible

– however create or destroy processes to often cause the

slow down of the systems

Main FunctionsTP Monitor: Funneling


• Client/Server application development fra

mework: TP monitor as middleware

• Firewalls of protection

• High availability

• Load balancing

• Scalability of function

• Reduced system cost

BenefitsTP Monitor


• TP-Lite is the concept of embedding TP Mo

nitor into the DBMS

• TP-Heavy is the way to put TP Monitor as a

separate item

TP-lite & TP-heavy


• Limit by the way the TP monitor is built

• When nested transaction

– TP-Lite is limited because mostly DBMS call

nested transaction separately

Scope of “commitTP-lite & TP-heavy


PerformanceTP-lite & TP-heavy

• TP-Heavy reduce the load of server


Reference Books

Client/server survival guide 3rd edition by Robert Orfali, Dan

Harkey, Jeri Edwards (John Wiley & Sons: 1999)

Client Server Computing: A Management Overview by Patric

k Martin (http://www.natlearn.com.au/cliserco.htm: Novem

ber1998)

Clinet/Server Applications (http://doro.srv.gc.ca/gena/ai/client

_e.html: July 1997)


Reference Books

Scale Up with TP Monitors by Jim Gray and Jeri Edwards (By

te Magazine: April 1995)

Next-Generation TP Monitors by Nick Gall (http://www.nwc.c

om/816/816colgall.html: August 1999)

Documents

Kittiphan Techakittiroj (09/05/58 10:21 น. 09/05/58 10:21 น. 09/05/58 10:21 น.) Transaction Processing Kittiphan Techakittiroj [email protected]