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new oracle dba terminologies – explained in one line

This is  to give you an idea about the various dba terminologies in case you are a new dba.
The idea is to try to get the information in one line..

if you are a new dba and dont know what a word means even after searching in google then  put your comment here and it will be added to this list.

sql -> commands you write to access and modify the data in the database.
pl/sql -> a collection of sql statements that can be executed as one big group.
triggers -> these are created on top of tables and used to manipulate the data that you are inserting or updating on the table.
sqlplus -> the tool that you use to execute sql scripts and the tool with which you can peform majority of database administration tasks
database control -> a web based component in 10g with which you can administer the database through gui screens
grid control -> a licensed component of 10g that you can use to administer thousands of databases from one main webpage..
management server -> the grid control saves its data here and uses the data to make decisions on how to administer the database effectively.
agent -> These are like watchmen whom you install on every server and they send information into the management server which is then used by the grid control.
listener -> a gatekeeper on the server where the database is located. if you want to connect to the database from a different machine then you need the listener.
listener.ora -> this is a text file where you enter some parameters like listener name , which databases it is monitoring etc.
tnsnames.ora -> the file that contains the database name , server name , database alias etc and which you need if you want to connect to the database specifying an alias.
sqlnet.ora -> a file that you use to specify whether you will use server name resolution  using tnsnames.ora or active directory etc
ORACLE_HOME -> this is where your oracle installation files will be placed
instance -> when you start oracle , the place occupied by oracle in the servers memory.
database -> all the physical datafiles like system datafile , sysaux datafile, control file etc are called together as the database.
cron -> this is a scheduling tool on a unix server
sqlldr -> this is a tool from oracle to load huge amounts of data from normal text files into the database.
toad -> a popular tool used to connect to the database and perform both database administration and development
oracle developer -> a tool from oracle through which you can perform oracle development
passwordfile -> this is a special file related to the oracle database where you can add special users so that they will have either the sysdba or sysoper privileges
sysdba or sysoper privileges ->  these are very advanced privileges using which you can do anything in the database.
scp -> this is a program using which you can transfer files ecurely from one server to another server
port -> ports are like numerous doors to a server and you shoukd know the door number(port number) to connect to the server.for example the oracle listener by default uses the 1521 port.
oracle client -> you need this software to connect from your machine to a oracle database and if you want to use sqlplus from your machine.
odbc driver -> you can imagine this as a translator who can translate english to german and german to english etc. The odbc driver is used as a middle man so applications and databases can talk with each                 other. This is because applications speak a different language and databases speak a different language.
raw disks -> pull out the hard disk from your compiter. that is a raw disk or raw device.
file system -> can you see your C drive on your computer? that is a file system where you can create your folders.
server process->this is a worker who performs all the work in the database when you want todo anything in the database.
client process -> it is your worker on your machine which will then talk to the listener on the database server and then with the server process.
system data file -> the most crucial file of the database. if this is damaged then you cant repair ir.  you must only get it from the backup.
sysaux data file -> the special file which started with 10g and which contains intelligence information about the database.
control file -> the brain of the database. without this your database will not start.
redo log file -> all the changes that you make to the database first gets saved in the redo log files and then into the data files.

pfile-> this is the database parameter file(normally called as init.ora or inityourdbname.ora) where you specify all database specific parameters. If you have only pfile and no spfile then you must start the

           database specifying startup pfile= ‘your path where this file is present’ . If you dont specify the pfile with startup command then oracle will by default look for the inityourdbname.ora in       

   $ORACLE_HOME/dbs folder.
        you can edit the pfile on unix systems with the vi editor. if you change any parameter in the pfile then you must restart the database to make the parameter effective.
spfile -> this is same like pfile but you cant edit this file. normally dba’s first create a pfile and then create a spfile using the pfile. The command to create the spfile is
           create spfile from pfile; This will make oracle to create the spfile under $ORACLE_HOME/dbs folder. If you want to specify where the spfile should be created then use this command
          create spfile = ‘your path name’ from pfile;
          The advantange of spfile is that you can change lot of parameters without restarting the database.
archivelog -> the redo log is backed up regularly if the database is in archivelog mode. These backed up redolog files are called as archivelogs.
              imagine you have one glass in your hand and you put it under a tap. what will happen once the glass is full .water what you can do is to pour the water into a different glass and
              then put the first glass under the tap. so you have backed up your glass. Treat the archive log the same way. archivelogs are useful when our database crashes. oracle will use the archive logs 

              to recover the database.
unix environment variables -> if you are working in a unix environment you use variables like $ORACLE_HOME or $HOME etc. so it means first you define a variable called ORACLE_HOME and if you want to reference it afterwards you must use the $ sign you use $ORACLE_HOME. If i want to set a variable from the command prompt i normally use export ORACLE_HOME=’my oracle path’. Then if i want to see the value of the
variable then i use echo $ORACLE_HOME.
undo data file -> if you are making changes to the data in the database then oracle keeps a copy of the data in undo files .so if you want undo your changes then oracle uses this image in the undo data file to undo the changes. for example imagine you are typing something in a word document ..then if you want undo what you types either you use the edit -> undo button oracle uses this undo file to undo its changes.
tempfile -> tempfile is a file where oracle performs huge data calculations as huge data calculations dont fit in the oracle instance. what would you do if you want to calculate 2 * 2 would do it immediately in your  mind and feel proud. now if i ask you to do 12345678 * 12345678..unless you are a superman/woman you would need a calculator. so because there is no place in your mind you are using temporarily your calculator to make your also exactly the same name .what cant fit in its memory will be fit into its temp file and once the calculation is done then the temp file is not used until the next calculation.

rman-> rman is a tool provided by oracle to perform backups.
rman incremental backups -> imagine you took a backup on monday . then you took a incremental backup on tuesday. this means on tuesday you are backing up only those blocks that were changed between monday

and tuesday and you already know that a datafile is nothing but a collection of blocks.
block-> Imagine a block is like a rectangular box and contains rows. so when you insert rows into a table then the rows are actually stored in blocks.
extent->it is a collection of blocks
segment->it is a collection of extents
datafile -> it is a collection of segments.
oracle optimizer -> it is a component of the database which decides the best way to return data from the database to the whenever you execute a query the optimizer has to decide the best way to

return the data to you.
oracle jobs-> These are internal oracle processes which performs the work that you ask them to do. you can decide to perform some task after 5 you just have to create a job and make sure that it

will execute after 5 hours and it will then automatically execute after 5 hours.
oratab-> this isa file which normally is present in the /var/opt/oracle location and contains a single line like below
         That entry is used normally by the unix server processes when the server is restarted so the server knows which databases are on the server and which databases it can start automatically.
.profile -> this is the file normally in the home directory of any user .for example /home/oracle . this file is executed everytime when you log into the server as a you can use this file to set some             generic variables and so you dont have to manually set each time.
tnsping-> when you want to test whether the database entry in your tnsnames.ora file is working correctly. you can just use tnsping namefromtnsnames.ora  ..example tnsping databasealias.

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