Why in Oracle SQL the deleted (uncommited) rows are not visible in current session but visible to other session?

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When a delete query is executed from where exactly the data is deleted? Why the data is still visible in other session? What all background process are carried out when delete query is fired in Oracle SQL (at architecture level)?


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Here’s the link provided in the answer above: Oracle® Database Concepts – Data Concurrency and Consistency.

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  • AshishSingh10

    Hi,

    In Oracle SQL we well know the ACID properties where you know about the multi-version concurrency control.when you start  the transaction, a timestamp identifies the start time.When the transaction  is running, they will not show any type of data inserted with timestamp after the start time, here the system keeps all previous versions of data page that are still available for transaction running. The confusion regarding the uncommitted state why  it is not visible in the currents session because  Whenever the transaction writes the page, they create a  new copy with a new timestamp meanwhile that copy is not available for  other transaction until and unless the updated transaction commit and only those transactions available which are present after commit state.

    Thanks & Regards

    Ashish@S 

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