OCP exam notes（2）

1. Database Initialization Parameter

• Parameter ---- basic / advance
  
• Hidden parameter 
  

2. Initialization Parameter File

        SPFILE ( continuously read and update ) ---- V$SPPARAMETER ---- shows the values stored in the spfile on disk

        PFILE ( only read once at instance startup ) ---- V$PARAMETER( isbasic='TURE' ) ---- shows the parameter values currently in effect in the running instance

        *****Special Parameter: OPTIMIZER_MODE ----values--- ALL_ROWS: complete ASAP

                                                                                                          --- FIRST_ROWS: feedback to user ASAP

3. Database startup and shutdown 

    Normal order : Database control ---> Database listener ---> Database

                                               |

   The configuration of Database Control is done at database creation time: the hostname, the TCP port ( https://hostname:port/em )

   Normal stages: nomount --------> mount ----------> open

                                 (spfile/pfile)    (controlfile)       (datafiles&redo logs)

   The syntax of CONNECT:

• The default of data dictionary authentication: sqlplus user/pwd[@connect_alias]
• The password file authentication: sqlplus user/pwd[@connect_alias] as sysdba
• The operation system authentication: sqlplus / as sysdba

        ****tip: SYSDBA and SYSAUX are not users but privileges

    The order oracle database find the spfile when instance startup: spfileSID.ora ---- spfile.ora ---- initSID.ora

    Shutdown options:

• normal --- no new user, all current connections are allowed to continue.
  
• transactional --- no new user, sessions currently involved in transaction are allowed to complete.
  
• immediate --- no new session, all currently connected sessions are terminated.
  
• abort --- equivalent of a power failure.

4. Oracle network

     Graphical tools to Manage Oracle Net : Enterprise Manager ( Database Control or Grid Control ), the Net Manager, the Net Configuration Assistant

     Database Registration: static and dynamic

          dynamic : preferred method, PMON process will use "local_listener" parameter to locate a listener. (register should after the listener start )

     Three critical files involved in configuration Oracle Net:

• listener.ora --- server-side file
  
• tnsnames.ora --- client-side file
  
• sqlnet.ora --- server-side, client-side or both,It contains settings that apply to all connections and listeners, such as security rules and encryption.
  

5. Oracle Share Server Architecture ( PGA uses share memory )

    user process- dispatcher |                                                                                                                                    |response queue --- user process

    user process- dispatcher | --- common queue --- share server processes --- parse-bind-execute --- |response queue --- user process

    user process- dispatcher |                                                                                                                                    |response queue --- user process

    User global area ( UGA ) in large pool of SGA is used to stores most of the session data

    Two parameters for share server configuration : dispatchers & shared_servers

    Share Server save memory space but will reduce performance ( take longer time and use more CPU ).