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In a SQL database, a record is typically called a "row". The introduction of granular (subset) locks creates the possibility for a situation called deadlock. Deadlock is possible when incremental locking (locking one entity, then locking one or more additional entities) is used. To illustrate, if two bank customers asked two clerks to obtain ...
Oracle Database (commonly referred ... Schema Annotations, Data Use Case Domains, Column Value Lock-free Reservations ... Polymorphic Table Functions, Active ...
Implementations from version 8 of Oracle Database onwards have included features associated with object-orientation. One can create PL/SQL units such as procedures, functions, packages, types, and triggers, which are stored in the database for reuse by applications that use any of the Oracle Database programmatic interfaces.
In database management systems, block contention (or data contention) refers to multiple processes or instances competing for access to the same index or data block at the same time. In general this can be caused by very frequent index or table scans, or frequent updates.
In databases and transaction processing, two-phase locking (2PL) is a pessimistic concurrency control method that guarantees conflict-serializability. [1] [2] It is also the name of the resulting set of database transaction schedules (histories).
Rdb is built on top of a low-level database kernel named KODA, which handles functionality such as locking, journaling, and buffering of data. [12] The KODA kernel is shared with Oracle's CODASYL DBMS (originally known as VAX DBMS) which is a network model database.
Fully exploiting a hardware configuration requires a variety of locking techniques, ranging from locking an entire database to entire tables to disk blocks to individual table rows. The appropriate lock granularity depends on the workload. The smaller the object that is locked, the less the chance of database requests blocking each other, while ...
For example, if a user UPDATEs a salary-value in a table containing employee-related data, the DBMS generates a redo record containing change-vectors that describe changes to the data segment block for the table. And if the user then COMMITs the update, Oracle generates another redo record and assigns the change a "system change number" (SCN).