Skip to main content

19. Oracle Processes

Processes

Oracle uses many small (focused) processes to manage and control the Oracle instance. This allows for optimum execution on multi-processor systems using multi-core and multi-threaded technology.

Some of these processes include:

PMON - Process Monitor

SMON - System Monitor

ARCn - Redo Log Archiver

LGWR - Redo Log Writer

DBWn - Database Writer

CKPT - Checkpoint process

RECO - Recoverer

CJQn - Job Queue Coordinator

QMNn - Queue-monitor processes

Dnnn - Dispatcher Processes (multiplex server-processes on behalf of users)

Snnn - Shared server processes (serve client-requests)

MMAN - Internal process (used for internal database tasks)

LSP0 - Logical standby coordinator process (controls Data Guard log-application)

MRP - Media-recovery process (detached recovery-server process)

MMON - Memory-monitor process

MMNL - Memory monitor light (gathers and stores AWR statistics)

PSP0 - Process-spawner (spawns Oracle processes)

RFS - Remote file server process (archive to a remote site)

DBRM - DB resource manager (new in 11g)

DIAGn - Diagnosability process (new in 11g)

FBDA - Flashback data archiver process (new in 11g)

VKTM - Virtual Timekeeper (new in 11g)

Wnnn - Space Management Co-ordination process (new in 11g)

SMCn - Space Manager process (new in 11g)

An instance can mount and open one and only one database.
A database can normally only be mounted and opened by one instance. However, when using Real Application Clusters (RAC) a database can be mounted and opened by many instances.

Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

Question 8: Aggregate Functions

Examine the description of the STUDENTS table: STD_ID NUMBER(4) COURSE_ID VARCHARD2(10) START_DATE DATE END_DATE DATE Which two aggregate functions are valid on the START_DATE column? (Choose two) A. SUM(start_date) B. AVG(start_date) C. COUNT(start_date) D. AVG(start_date, end_date) E. MIN(start_date) F. MAXIMUM(start_date) Answer: C & E Explanation: It is possible to apply COUNT() and MIN() functions on the column with DATE data type. Incorrect Answers A: Function SUM() cannot be used with DATE data type column. B: Function AVG() cannot be used with DATE data type column. D: Function AVG() cannot be used with DATE data type column, and function AVG() just has one parameter X, not two. It averages all X column values returned by the SELECT statement. F: There is no MAXIMUM() function in Oracle, only MAX() function exists.
Post a Comment
Read more

18. ADDING CHECK CONSTRAINT WHILE INSERTING.

Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER NOT NULL EMP_NAME VARCHAR2(30) JOB_ID VARCHAR2(20) SAL NUMBER MGR_ID NUMBER DEPARTMENT_ID NUMBER You want to create a SQL script file that contains an INSERT statement. When the script is run, the INSERT statement should insert a row with the specified values into the EMPLOYEES table. The INSERT statement should pass values to the table columns as specified below: EMPLOYEE_ID: Next value from the sequence EMP_ID_SEQEMP_NAME and JOB_ID: As specified by the user during run time, through substitution variables SAL: 2000 MGR_ID: No value DEPARTMENT_ID: Supplied by the user during run time throughsubstitutionvariable. The INSERT statement should fail if the user supplies a value other than20 or 50. Which INSERT statement meets the above requirements? A. INSERT INTO employees VALUES (emp_id_seq.NEXTVAL, '&ename', '&jobid', 2000, NULL,&did); B. INSERT INTO employees VALUES (emp_id_seq.NEXTVAL, '...
Post a Comment
Read more