Friday , June 23 2017

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SHARED SERVER ARCHITECTURE

SHARED SERVER ARCHITECHTURE

  SHARED SERVER ARCHITECTURE Multiple user requests will be received by dispatcher which will be placed in request queue. Shared server processes will take information from request queue and will be processed inside the database. The results will be placed in response queue from where dispatcher will send them to …

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DATABASE OPERATING MODES

STUTDOWN TYPES

DATABASE OPERATING MODES STARTUP PHASES Commands:SQL> startup or         SQL> startup nomount                        SQL> alter database mount;                        SQL> alter database open; Note: A database can be started without issuing shutdown command using SQL> startup force SHUTDOWN TYPES Read More: PARAMETER FILE Background Processors SMON’s instance recovery with example

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OPTIMAL FLEXIBLE ARCHITECTURE (OFA)

OPTIMAL FLEXIBLE ARCHITECTURE

OPTIMAL FLEXIBLE ARCHITECTURE (OFA) Reading and writing to a hard disk will be done with the help of I/O header. For a hard disk there will be only one I/O header exists. As per OFA, oracle recommends to store all the physical files separately in different hard drives. In such …

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ALERT LOG & OTHER TRACE FILES

ALERT LOG & OTHER TRACE FILES

ALERT LOG & OTHER TRACE FILES Alert log is the monitoring file which records following information useful for DBA in diagnosing the errors in the database All oracle related errors Every startup and shutdown timestamp Non-default parameters Archivelog generation information Checkpoint information (optional) etc. Alert log file will only specifies …

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ASMM (AUTOMATIC SHARED MEMORY MANAGEMENT)

ASMM (AUTOMATIC SHARED MEMORY MANAGEMENT) In 9i, SGA has been made dynamic i.e. sizes of SGA components can be changed without shutting down the database. (not possible in 8i) Many times DBA’s faced problem in calculating correct memory sizes which lead to performance problems in instance level and DBA’s are …

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PARAMETER FILE

SPFILE

PARAMETER FILE This file contains parameters that will define the characteristics of database. It will be in the form of init<SID>.ora [SID – instance name] and resides in ORACLE_HOME/dbs (on unix) and ORACLE_HOME/database (on windows) Parameters are divided into two types Static parameters – the value for these parameters cannot …

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Background Processors

Background Processors PMON : It is responsible for following actions releases the locks and resources held by abruptly terminated sessions Note: whenever any user performs DML transactions on a table, oracle will apply lock. This is to maintain read consistency authenticates the user registers the listener information with the instance …

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SMON’s instance recovery with example

EXAMPLE 1

SMON’s instance recovery with example EXAMPLE : 1 In the above diagram, assume that 1,2 and 3 transactions are commited and 4 is going on. Also as checkpoint occurred at log switch, complete data of 1 and 2, also part of 3 were written to datafiles Assume LGWR is writing …

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COMPONENTS OF ORACLE DATABASE ARCHITECTURE

REDOLOG FILES & CONTROL FILES INTERVIEW QUESTIONS

COMPONENTS OF ORACLE DATABASE ARCHITECTURE USER PROCESS : It is the process which places request from client side and will be created when user starts any application. SERVER PROCESS : It is the process which will do work on behalf of user process on server side. PRIVATE GLOBAL AREA (PGA) …

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