General Oracle architecture

The architecture consists of:

  • Buffers
  • Processes
  • Files
  • Networking

Buffers are basically a bunch of sections in the memory that are allocated to Oracle for various different types of functions and these buffers are stored in RAM. So what actually buffers does is hold the most recent data that are been used which helps to retrieved the data, accessing from RAM is much more faster than accessing the data from the disk.

Processes are all the little programs that are all run in background that do everything inside Oracle, these are the services are running on services panel of the Windows OS. Those bunches of services are the Oracle processes. And same if we want to know from Linux box then we can use a command i.e. “ps – ef grep” and can see a bunch of Oracle processes.

Files are the data files which store the data. The log files stores the log entries, the archive log file stores copy of redo logs which are been recycled ,the control files are the pointers to all the other files and link them together. There are also from configuration files such as TNS.ora, networking files and parameter files etc.

Networking is nothing but the connectivity from the client to server across services across network using a special type of gateway networking software which actually allows you to connect to server from the client.

Memory Layer:

This is also called as SGA (Shared Global Area).

The layer has been divided into few chunks such as below:

  • Database buffers
  • Redo log buffer
  • Sort buffer
  • Shared Pool :
        • Parsed SQL and PL/SQL
        • Latches and Locks
        • Metadata

Process Layer is consists of all the back ground processes such as:

  • Database writer
  • Log writer
  • Archiver
  • PMON
  • SMON
  • Recoverer

 

Oracle instance is something which will be a combination of the entire Process layer, memory layer and all the files. If we combine everything then we will end up with Oracle database which will then use the Networking and the processes to communicate across the network.

 

Reference used from http://docs.oracle.com

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