Learning notes - distributed transaction theory

Distributed transactions

Local transactions

• A
  • Atomicity
  • All transaction operations , Or both , Or it's not done
• C
  • Uniformity
  • Before and after the transaction , The database consistency constraint is not broken
• I
  • Isolation,
  • The two transactions do not interfere with each other
• D
  • persistence
  • After the transaction completes , Data changes are persisted to the database , Will not be rolled back

Distributed transactions

• Distributed transactions
  • The transactions completed by different services through network remote cooperation are called distributed transactions
• scene
  • Microservices
  • A single entity accesses multiple databases
  • Multiple services access a database

CAP theory

• c

  • Uniformity

• a

  • Usability
  • ca Can't coexist

• p

  • Zone tolerance
  • must

• Combine

  • ap
    • Give up consistency
  • cp
    • Discard availability
    • Transfer accounts
  • ca
    • Discard partition

base theory

• Strong consistency and ultimate consistency
  • Basically
  • Soft state
  • Final consistency

Solution

2pc

• Two-phase commit
• form
  • Transaction manager
  • participants
• The process
  • Preparation stage
    • The transaction manager sends Prepare Message to participants
    • Participants execute transactions locally , Not submitted
    • Local records Undo/Redo journal （ Before the change / Modified data ）
  • Submission phase
    • If the transaction manager receives error Or timeout , Roll back the transaction

XA programme

• DTP Model
  • AP
    • Applications
  • RM
    • Explorer
  • TM
    • Transaction manager
  • XA
    • TM And RM Direct interface specification Protocol

seata programme

• Open source distributed transaction framework
• Global transaction
• Branch business
• Concept
  • RM
    • Control branch transactions
  • TM
    • Transaction manager
    • Embedded applications
  • TC
    • Transaction coordinator
    • Independent operation
• technological process
  • TM towards TC Request to open global transaction , Generating uniqueness XID
  • RM towards TC Register branch transactions , Included in the XID The overall affairs of
  • completion of enforcement ,TM towards TC Initiate heap XID The global commit or rollback resolution for
  • TC Dispatch XID The branch transaction of completes the commit or rollback

TCC

• TCC
  • Try
    • Preprocessing
  • confirm
    • Business confirmation
  • cancel
    • revoke
• frame
  • Hmily

The final consistency of reliable information

• The final consistency of reliable information
  • Local transactions and message sending atomicity
  • The reliability of the message received by the transaction participant
  • The problem of repeated consumption of news
• programme
  • Local message table scheme
  • RocketMq Transaction message scheme

Best effort notification

• RocketMq Best effort notification scheme