What is a database transaction

Question

Can someone provide a straightforward  but not simpler than possible  explanation of a transaction as applied to computing  even if copied from Wikipedia

User · Answer

A series of data manipulation statements that must either fully complete or fully fail  leaving the database in a consistent state

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A transaction is a way of representing a state change  Transactions ideally have four properties  commonly known as ACID    Atomic  if the change is committed  it happens in one fell swoop  you can never see  half a change   Consistent  the change can only happen if the new state of the system will be valid  any attempt to commit an invalid change will fail  leaving the system in its previous valid state  Isolated  no-one else sees any part of the transaction until it s committed  Durable  once the change has happened - if the system says the transaction has been committed  the client doesn t need to worry about  flushing  the system to make the change  stick     See the Wikipedia ACID entry for more details   Although this is typically applied to databases  it doesn t have to be   In particular  see Software Transactional Memory

User · Answer

Transaction is an indivisible unit of data processing -All transactions must have the ACID properties   ie Atomicity Consistency Isolation and Durable Transaction is all or nothing but not intermidiate  it means if you transfer your money from one account to another account one account have to lose that much and other one have to gain that amount but if you transfer money from one account and another account is still empty that will be not a transaction

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http   en wikipedia org wiki Database transaction http   en wikipedia org wiki ACID ACID   Atomicity  Consistency  Isolation  Durability  When you wish for multiple transactional resources to be involved in a single transaction  you will need to use something like a two-phase commit solution  XA is quite widely supported

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Transaction - is just a logically composed set of operations you want all together be either committed or rolled back

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Transaction can be defined as a collection of task that are considered as minimum processing unit  Each minimum processing unit can not be divided further    The main operation of a transaction are read and write   All transaction must contain four properties that commonly known as ACID properties for the purpose of ensuring accuracy   completeness and data integrity

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A transaction is a sequence of one or more SQL operations that are treated as a unit   Specifically  each transaction appears to run in isolation  and furthermore  if the system fails  each transaction is either executed in its entirety or not all   The concept of transactions is motivated by two completely independent concerns  One has to do with concurrent access to the database by multiple clients  and the other has to do with having a system that is resilient to system failures   Transaction supports what is known as the ACID properties    A  Atomicity  C  Consistency   I  Isolation  D  Durability

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I think a transaction is an atomic action in terms of DBMS    that means it cannot be seperated  yes  in a transction  there may be several instructions for the system to execute  but they are binded together to finished a single basic task   for example  you need to walk through a bridge  let s treat this as a transction   and to do this  say  you need 100 steps  overall  these steps cannot be seperated  when you ve done half of them  there is only two choice for you  continue to finish them all  and go back to the start point  it s just like the to result of a transaction  success  committed   and fail  rollback

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I would suggest that a definition of  transaction processing  would be more useful  as it covers transactions as a concept in computer science   From wikipedia   In computer science  transaction processing is information processing that is divided into individual  indivisible operations  called transactions  Each transaction must succeed or fail as a complete unit  it cannot remain in an intermediate state   http   en wikipedia org wiki Transaction processing Implementations

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Here s a simple explanation  You need to transfer 100 bucks from account A to account B  You can either do   accountA -  100  accountB    100    or  accountB    100  accountA -  100    If something goes wrong between the first and the second operation in the pair you have a problem - either 100 bucks have disappeared  or they have appeared out of nowhere   A transaction is a mechanism that allows you to mark a group of operations and execute them in such a way that either they all execute  commit   or the system state will be as if they have not started to execute at all  rollback    beginTransaction  accountB    100  accountA -  100  commitTransaction    will either transfer 100 bucks or leave both accounts in the initial state

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In addition to the above responses  it should be noted that there is  at least in theory  no restriction whatsoever as to what kind of resources are involved in a transaction   Most of the time  it is just a database  or multiple distinct databases  but it is also conceivable that a printer takes part in a transaction  and can cause that transaction to fail  say in the event of a paper jam

User · Answer

A transaction is a unit of work that you want to treat as  a whole   It has to either happen in full or not at all   A classical example is transferring money from one bank account to another  To do that you have first to withdraw the amount from the source account  and then deposit it to the destination account  The operation has to succeed in full  If you stop halfway  the money will be lost  and that is Very Bad   In modern databases transactions also do some other things - like ensure that you can t access data that another person has written halfway  But the basic idea is the same - transactions are there to ensure  that no matter what happens  the data you work with will be in a sensible state  They guarantee that there will NOT be a situation where money is withdrawn from one account  but not deposited to another

[database] What is a database transaction?

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