SMON Performs critical tasks such as crash recovery when the instance is started following a failure, dead transaction recovery, and maintenance tasks such as temporary space reclamation, data dictionary cleanup, and undo tablespace management. The system monitor process (SMON) performs many database maintenance tasks, including the following: *Creates and manages the temporary tablespace metadata and … Read more
Transparent Data Encryption (TDE) enables you to encrypt sensitive data that you store in tables and tablespaces. After the data is encrypted, this data is transparently decrypted for authorized users or applications when they access this data. TDE helps protect data stored on media (also called data at rest) in the event that the storage … Read more
The redo log buffer is a circular buffer in the SGA that stores redo entries describing changes made to the database.A redo record is a data structure that contains the information necessary to reconstruct, or redo, changes made to the database by DML or DDL operations. Database recovery applies redo entries to data files to reconstruct lost changes.The database … Read more
The shared pool caches various types of program data.For example, the shared pool stores parsed SQL, PL/SQL code, system parameters, and data dictionary information. The shared pool is involved in almost every operation that occurs in the database. For example, if a user executes a SQL statement, then Oracle Database accesses the shared pool. This section includes the following … Read more
The PGA is memory specific to an operating process or thread that is not shared by other processes or threads on the system. Because the PGA is process-specific, it is never allocated in the SGA. The PGA is a memory heap that contains session-dependent variables required by a dedicated or shared server process. The server … Read more
The UGA is session memory, which is memory allocated for session variables, such as logon information, and other information required by a database session. Essentially, the UGA stores the session state. If a session loads a PL/SQL package into memory, then the UGA contains the package state, which is the set of values stored in … Read more
A checkpoint is an operation that Oracle performs to ensure data file consistency. When a checkpoint occurs, Oracle ensures all modified buffers are written from the data buffer to disk files. Frequent checkpoints decrease the time necessary for recovery should the database crash, but may decrease overall database performance. A checkpoint performs the following three … Read more
Sometimes the DBA requires to create the read-only user for a particular schemas.While creating the user,one should always keep in mind that the user should have minimum privileges. There is no any direct command to create the read-only user in oracle. Sometimes I find people grants “read any table ” privileges to create the read-only … Read more
Datafiles are part of the Oracle Database, these are the files that have the actual data in them. Datafiles can be located on ASM or file system on disk. So either you can add datafile in ASM or else you can add datafiles to tablespace in Oracle located on file system. There are two different … Read more
DB_NAME On a primary database, specify the name used when the database was created. On a physical standby database, use the DB_NAME of the primary database. DB_UNIQUE_NAME Specify a unique name for each database. This name stays with the database and does not change, even if the primary and standby databases reverse roles. LOG_ARCHIVE_CONFIG The … Read more