TX (Transaction) Locks


  • Manual Locking and User-Defined Locks- Locking and Latching

    So far, we have looked mostly at locks that Oracle places for us transparently. When we update a table, Oracle places a TM lock on…

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  • Setting Up for the Test- Locking and Latching

    In order to test, we’ll need a schema (set of tables) to work with. We’ll be testing with multiple users and want to measure the…

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  • Latches- Locking and Latching

    Latches are lightweight serialization devices used to coordinate multiuser access to shared data structures, objects, and files. Latches are locks designed to be held for…

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  • DDL Locks- Locking and Latching-2

    A view that is invaluable for looking at this information is DBA_DDL_LOCKS. There is no V$ view. The DBA_DDL_LOCKS view is built on the more…

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  • Latch “Spinning”- Locking and Latching

    One thing I’d like to drive home with regard to latches is this: latches are a type of lock, locks are serialization devices, and serialization…

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  • Blocked Merges, Updates, and Deletes- Locking and Latching-1

    In an interactive application—one where you query some data out of the database, allow an end user to manipulate it, and then put it back…

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  • Optimistic or Pessimistic Locking? – Locking and Latching

    So which method is best? In my experience, pessimistic locking works very well in Oracle (but perhaps not so well in other databases) and has…

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  • Blocked Inserts- Locking and Latching

    There are a few times when an INSERT will block. The most common scenario is when you have a table with a primary key or…

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  • Blocked Merges, Updates, and Deletes- Locking and Latching-3

    This script works on foreign key constraints that have up to eight columns in them (if you have more than that, you probably want to…

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  • TX (Transaction) Locks- Locking and Latching-3

    However, before we can say that we have a good understanding of how the row locking in Oracle works, we must look at one last…

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