mylearning4oracle

Logical Backups:- ================= Logical backup can be considered as an alternate backup solution but not as main stream backup solution Useful in the case of databae upgration and database migrations Logical backups are platform independent It is useful in the case of data reorganisation Useful incase of moving objects from one schema to another schema Logical backups generate dump files and log files and we cannot edit dump files otherwise it will be corrupted Dump files contains meta data as well as business data we can take incremental bacups using logical backups and dump files cannot be imported using impdp utility Export can be done in 2 ways coventional path and direct path In conventional path it uses sql statement to bring the data from disk  to buffer cache and then it is evaluated to and traferred to export client which writes data to dump file In direct path , it will directly reads data from disk into export session of PGA and then transfers to expo...

Oracle memory architecture is divided in following memory structure:- System Global Area (SGA):- This is a large, shared memory segment that virtually all Oracle processes will access at one point or another. Process Global Area (PGA): This is memory that is private to a single process or thread; it is not accessible from other processes/threads. User Global Area (UGA): This is memory associated with your session. It is located either in the SGA or the PGA, depending whether you are connected to the database using a shared server (it will be in the SGA), or a dedicated server (it will be in the PGA). PGA is the memory reserved for each user process connecting to an Oracle Database and is allocated when a process is created and deallocated when a process is terminated. Contents of PGA:- Private SQL Area: Contains data such as bind information and run-time memory structures. It contains Persistent Area which contains bind information and is freed only when the curs...

What are Database Link: ======================= A database link is one way method of accesing a remote database from other database provided the link should be existing in the dictionary of the local database. We usually create a DB link based on the DB global database name. eg: == A database link connection is one-way in the sense that a client connected to local database A can use a link stored in database A to access information in remote database B, but users connected to database B cannot use the same link to access data in database A. If local users on database B want to access data on database A, then they must define a link that is stored in the data dictionary of database B. A database link connection allows local users to access data on a remote database. For this connection to occur, each database in the distributed system must have a unique global database name in the network domain. The global database name uniquely identifies a database server in a distribu...

Golden gate: =========== Golden gate software was founded in the year 1995 and name after famous golden gate bridge Golden gate was founded by eric fish and tod davidson Golden gate features: ==================== Real time data replication is one of the basic feature of golden gate It provides high availability by acting as live stand-by target for a primary target It provides  zero downtime upgrades and migrations It provides live reporting for the operational databases Golden gate Processes: ===================== Manager process Extract Process(capture process) replicat Process Trail files Data Pump Server Collector Extract Process: =============== It reads the data from the online redo logs of the database and typically does not require connection to the database. The extract process will regularlily checkpoint its read and write position, typically to a file. Trail  Files:- ============ Trail files basically contains the canonical format o...

Oracle Kernel Parameters: ======================== We have different kernel parameters  SHM means shared memory segments , which are being used by the SGA shmax ->  It defines the maximum size of shared memory segment shmin ->  It defines the minimum size of shared memory segment shmni ->  It defines the maximum  number of shared memeory segments available on the system shmall -> It defines the total amoumnt of shared memory allocated  on the system Semaphore , it is a way of locking or applying flag on shared memory semmsl -> number of semaphores per set semmns -> total number of available semaphores semopm -> number of operations can be performed per semaphore call file_max -> defined number of files can be opened at once ip_local_port_range -> defines the port range rmem_default and rmem_max -> defines the min and max size of receive buffer wmem_default and wmem_max -> defines the min and max siz...