1. 12/23/12 Dba 3+ exp qus
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3+Years Oracle DBA Interview Questions
February 9, 2011 Mario Alcaide Leave a comment Go to comments
In response for a reader of this blog who asked me for some interview questions for a 3+Year
experienced DBA, I have written this series of questions that you can use in your interviews.
Either if you are the interviewer, or the interviewer. Enjoy!
1. Basic (Every DBA should answer correctly ALL these questions. This knowledge is just basic
for a 3+ year experienced DBA)
1.1 Q- Which are the default passwords of SYSTEM/SYS?
A- MANAGER / CHANGE_ON_INSTALL Related
1.2 Q- How can you execute a script file in SQLPLUS?
A- To execute a script file in SQLPlus, type @ and then the file name.
Oracle 10g Db Rel 1
1.3 Q- Where can you find official Oracle documentation?
2619 views
A- tahiti.oracle.com
1.4 Q- What is the address of the Official Oracle Support?
A- metalink.oracle.com or support.oracle.com
1.5 Q- What file will you use to establish Oracle connections from a remote client?
A- tnsnames.ora Oracle10gdbrel1 090915024957-
1.6 Q- How can you check if the database is accepting connections? phpapp02
A- lsnrctl status or lsnrctl services 488 views
1.7 Q- Which log would you check if a database has a problem?
A- Alert log
1.8 Q- Name three clients to connect with Oracle, for example, SQL Developer: B10742
A- SQL Developer, SQL-Plus, TOAD, dbvisualizer, PL/S QL Developer… There are several, but
an experienced dba should know at least three clients. 409 views
1.9 Q- How can you check the structure of a table from sqlplus?
A- DESCRIBE or DESC
1.10 Q- What command will you start to run the installation of Oracle software on Linux?
A- runInstaller Oracle backup and recovery
397 views
2. Moderate (Standard knoledge for a daily-work of every DBA. He could fail one or two
questions, but not more)
‹› 2.1 Q- What should you do if you encounter an ORA-600?
A- Contact Oracle/17Support 2516186 oracle9i-dba-fundamentals-
1
2.2 Q- Explain the differences between PFILE and SPFILE
ii-volume-ii
A- A PFILE is a Static, text file that initialices the database parameter in the moment that it‟s
started. If you want to modify parameters in PFILE, you have to restart the database. 889 views
A SPFILE is a dynamic, binary file that allows you to overwrite parameters while the database is
already started (with some exceptions)
2.3 Q- In which Oracle version was Data Pump introduced? Oracle 10g 2 day dba course
A- Oracle 10g 441 views
2.4 Q- Say two examples of DML, two of DCL and two of DDL
A- DML: SELECT, INSERT, UPDATE, DELETE, MERGE, CALL, EXPLAIN PLAN, LOCK
TABLE
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1. 3+Years Oracle DBA Interview QuestionsFebruary 9, 2011 Mario Alcaide
Leave a comment Go to commentsIn response for a reader of this blog who
asked me for some interview questions for a 3+Yearexperienced DBA, I have
written this series of questions that you can use in your interviews.Either if
you are the interviewer, or the interviewer. Enjoy!1. Basic (Every DBA should
answer correctly ALL these questions. This knowledge is just basicfor a 3+
year experienced DBA)1.1 Q- Which are the default passwords of
SYSTEM/SYS?A- MANAGER / CHANGE_ON_INSTALL1.2 Q- How can you
execute a script file in SQLPLUS?A- To execute a script file in SQLPlus, type
@ and then the file name.1.3 Q- Where can you find official Oracle
documentation?A- tahiti.oracle.com1.4 Q- What is the address of the Official
Oracle Support?A- metalink.oracle.com or support.oracle.com1.5 Q- What file
will you use to establish Oracle connections from a remote client?A-
tnsnames.ora1.6 Q- How can you check if the database is accepting
connections?A- lsnrctl status or lsnrctl services1.7 Q- Which log would you
check if a database has a problem?A- Alert log1.8 Q- Name three clients to
connect with Oracle, for example, SQL Developer:A- SQL Developer, SQL-
Plus, TOAD, dbvisualizer, PL/SQL Developer… There are several, butan
experienced dba should know at least three clients.1.9 Q- How can you check
the structure of a table from sqlplus?A- DESCRIBE or DESC1.10 Q- What
command will you start to run the installation of Oracle software on Linux?A-
runInstaller2. Moderate (Standard knoledge for a daily-work of every DBA. He
could fail one or twoquestions, but not more)2.1 Q- What should you do if
you encounter an ORA-600?A- Contact Oracle Support2.2 Q- Explain the
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3. 12/23/12 Dba 3+ exp qus
differences between PFILE and SPFILEA- A PFILE is a Static, text file that
initialices the database parameter in the moment that it‟sstarted. If you want to
modify parameters in PFILE, you have to restart the database.A SPFILE is a
dynamic, binary file that allows you to overwrite parameters while the
database isalready started (with some exceptions)2.3 Q- In which Oracle
version was Data Pump introduced?A- Oracle 10g2.4 Q- Say two examples of
DML, two of DCL and two of DDLA- DML: SELECT, INSERT, UPDATE,
DELETE, MERGE, CALL, EXPLAIN PLAN, LOCKTABLE
2. DDL: CREATE, ALTER, DROP, TRUNCATE, COMMENT, RENAMEDCL:
GRANT, REVOKE2.5 Q- You want to save the output of an Oracle script from
sqlplus. How would you do it?A- spool script_name.txtselect * from
your_oracle_operations;spool off;2.6 Q- What is the most important
requirement in order to use RMAN to make consistent hotbackups?A- Your
database has to be in ARCHIVELOG mode.2.7 Q- Can you connect to a local
database without a listener?A- Yes, you can.2.8 Q- In which view can you find
information about every view and table of oracle dictionary?A- DICT or
DICTIONARY2.9 Q- How can you view all the users account in the database?
A- SELECT USERNAME FROM DBA_USERS;2.10 Q- In linux, how can we
change which databases are started during a reboot?A- Edit /etc/oratab3.
Advanced (A 3+ year experienced DBA should have enough knowledge to
answer thesequestions. However, depending on the work he has done, he
could still fail up to 4 questions)3.1 Q- When a user process fails, what Oracle
background process will clean after it?A- PMON3.2 Q- How can you reduce
the space of TEMP datafile?A- Prior to Oracle 11g, you had to recreate the
datafile. In Oracle 11g a new feature wasintroduced, and you can shrink the
TEMP tablespace.3.3 Q- How can you view all the current users connected in
your database in this moment?A- SELECT COUNT(*),USERNAME FROM
V$SESSION GROUP BY USERNAME;3.4 Q- Explain the differences between
SHUTDOWN, SHUTDOWN NORMAL, SHUTDOWNIMMEDIATE AND
SHUTDOWN ABORTA- SHUTOWN NORMAL = SHUTDOWN : It waits for
all sessions to end, without allowingnew connections.SHUTDOWN
IMMEDIATE : Rollback current transactions and terminates every
session.SHUTDOWN ABORT : Aborts all the sessions, leaving the database
in an inconsistent state. It‟sthe fastest method, but can lead to database
corruption.3.5 Q- Is it possible to backup your database without the use of an
RMAN database to store thecatalog?A- Yes, but the catalog would be stored
in the controlfile.3.6 Q- Which are the main components of Oracle Grid
Control?A- OMR (Oracle Management Repository), OMS (Oracle
Management Server) and OMA(Oracle Management Agent).3.7 Q- What
command will you use to navigate through ASM files?A- asmcmd3.8 Q- What
is the difference between a view and a materialized view?A- A view is a select
that is executed each time an user accesses to it. A materialized view storesthe
result of this query in memory for faster access purposes.3.9 Q- Which one is
faster: DELETE or TRUNCATE?
3. A- TRUNCATE3.10 Q- Are passwords in oracle case sensitive?A- Only
since Oracle 11g.4. RAC (Only intended for RAC-specific DBAs, with varied
difficultied questions)4.1 Q- What is the recommended method to make
backups of a RAC environment?A- RMAN to make backups of the database,
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4. Dba 3+ exp qus
dd to backup your voting disk and hard copies ofthe OCR file.4.2 Q- What
command would you use to check the availability of the RAC system?A-
crs_stat -t -v (-t -v are optional)4.3 Q- What is the minimum number of
instances you need to have in order to create a RAC?A- 1. You can create a
RAC with just one server.4.4 Q- Name two specific RAC background
processesA- RAC processes are: LMON, LMDx, LMSn, LKCx and DIAG.4.5
Q- Can you have many database versions in the same RAC?A- Yes, but
Clusterware version must be greater than the greater database version.4.6 Q-
What was RAC previous name before it was called RAC?A- OPS: Oracle
Parallel Server4.7 Q- What RAC component is used for communication
between instances?A- Private Interconnect.4.8 Q- What is the difference
between normal views and RAC views?A- RAC views has the prefix „G‟. For
example, GV$SESSION instead of V$SESSION4.9 Q- Which command will we
use to manage (stop, start…) RAC services in command-linemode?A-
srvctl4.10 Q- How many alert logs exist in a RAC environment?A- One for each
instance.5. Master (A 3+ year experienced DBA would probably fail these
questions, they are veryspecifid and specially difficult. Be glad if he‟s able to
answer some of them)5.1 Q- How can you difference a usual parameter and an
undocumented parameter?A- Undocumented parameters have the prefix „_‟.
For example, _allow_resetlogs_corruption5.2 Q- What is BBED?A- An
undocumented Oracle tool used for foresnic purposes. Stans for Block
Browser andEDitor.5.3 Q- The result of the logical comparison (NULL = NULL)
will be… And in the case of(NULL != NULL)A- False in both cases.5.4 Q-
Explain Oracle memory structureThe Oracle RDBMS creates and uses storage
on the computer hard disk and in random accessmemory (RAM). The portion
in the computer s RAM is called memory structure. Oracle has twomemory
structures in the computer s RAM. The two structures are the Program Global
Area(PGA) and the System Global Area (SGA).The PGA contains data and
control information for a single user process. The SGA is thememory segment
that stores data that the user has retrieved from the database or data that the
4. user wants to place into the database.5.5 Q- Will RMAN take backups of
read-only tablespaces?A- No5.6 Q- Will a user be able to modify a table with
SELECT only privilege?A- He won‟t be able to UPDATE/INSERT into that
table, but for some reason, he will still beable to lock a certain table.5.7 Q-
What Oracle tool will you use to transform datafiles into text files?A- Trick
question: you can‟t do that, at least with any Oracle tool. A very experienced
DBAshould perfectly know this.5.8 Q- SQL> SELECT * FROM
MY_SCHEMA.MY_TABLE;SP2-0678: Column or attribute type can not be
displayed by SQL*PlusWhy I‟m getting this error?A- The table has a BLOB
column.5.9 Q- What parameter will you use to force the starting of your
database with a corruptedresetlog?A-
_ALLOW_RESETLOGS_CORRUPTION5.10 Q- Name the seven types of
Oracle tablesA- Heap Organized Tables, Index Organized Tables, Index
Clustered Tables, Hash ClusteredTables, Nested Tables, Global Temporary
Tables, Object Tables.DBA TasksDecember 3, 2010 Mario Alcaide 1
commentWe can separate the dba tasks between daily, weekly and monthly
procedures:Daily- Verify instance status- Check alerts- Check configured
metrics- Check RMAN backups- Check storage- Check CPU contention-
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5. 12/23/12 Dba 3+ exp qus
Check waiting times- Check memory usage- Check network load- Check iostat
5. Weekly- Invalid objects- Tunning: indexes and execution plans- Top SQL-
Environments consistence- Review of ressource policy- Trends and peaks-
Cleaning of alert logs- Review of RMANMonthly- Recovery tests- Analyze
the data increment trend- Tunning- Review I/O- Fragmentation- Row chaining-
High Availability Analysis- Scalability- Schedule monthly downtimeDefault
passwords in OracleNovember 26, 2010 Mario Alcaide Leave a commentHave
you ever asked yourself which are the default passwords in Oracle?Here is the
list:SYS: CHANGE_ON_INSTALLSYSTEM: MANAGERSCOTT:
TIGERADAMS: WOODJONES: STEELBLAKE: PAPERFORD: CARKING:
GOLD
6. What is the data dictionary?July 8, 2010 Mario Alcaide Leave a
commentThe scope of this article is to clarify what exactly is the data
dictionary. Probably all of you haveheard of it, and you know it‟s a bunch of
metadata that Oracle uses to work, but if you want toknow more about this
Data Dictionary, then I hope this article teaches you something new.The data
dictionary is a repository of metadata (Information about information), about
all theinformation inside the database. This repository is owned by SYS, and is
stored principally in theSYSTEM tablespace, though some components are
stored in the SYSAUX tablespace (in Oracle10+).The data dictionary is
composed of tables and views. Some of these tables are inside of theOracle
kernel, so you would never work directly with them unless you are working for
Oraclesupport or performing a disaster recovery scenario. But instead you can
access to the views inorder to know the “information about the
information”.For example, a possible usage of this data dictionary would be to
know all the tables owned by asingle user, or the list or relationships between
all the tables of the database.The main view of the data dictionary is the view
DICT (or DICTIONARY):SQL> DESC DICTNombre ?Nulo? Tipo
—————————————– ——– —————————-
TABLE_NAME VARCHAR2(30)COMMENTS VARCHAR2(4000)Through the
DICT view, you can access to all the data dictionary views that could provide
youthe information that you need.For example, if you are looking for
information related to db_links, but you don‟t know where tolook for, then
query the DICT view:SQL> SELECT TABLE_NAME FROM DICT WHERE
TABLE_NAME LIKE‘%LINK%’;TABLE_NAME——————————
USER_DB_LINKSALL_DB_LINKSDBA_DB_LINKS
7. V$DBLINKGV$DBLINKNow, you have just to query one of these views to
find the data you are looking for. GV$ viewsare very useful when you are
working with RAC, and V$ views are instance related.Remember that the data
dictionary provides critical information of the database, and it should
berestricted to users. However, if a user really needs to query the data
dictionary, you can use thefollowing sentence:GRANT
SELECT_CATALOG_ROLE TO user_name;How would you determine the
time zone under which a database was operating?select DBTIMEZONE from
dual;Related Articles Oracle Technical Interview Questions Answered - Part1
Oracle Technical Interview22. Explain the use of setting GLOBAL_NAMES
equal to TRUE.Setting GLOBAL_NAMES dictates how you might connect to
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6. 12/23/12 Dba 3+ exp qus
a database. This variable iseither TRUE or FALSE and if it is set to TRUE it
enforces database links to have the same nameas the remote database to
which they are linking.23. What command would you use to encrypt a PL/SQL
application?WRAP24. Explain the difference between a FUNCTION,
PROCEDURE and PACKAGE.A function and procedure are the same in that
they are intended to be a collection of PL/SQLcode that carries a single task.
While a procedure does not have to return any values to thecalling
application, a function will return a single value. A package on the other hand
is acollection of functions and procedures that are grouped together based on
their commonality to abusiness function or application.25. Explain the use of
table functions.
8. Table functions are designed to return a set of rows through PL/SQL logic
but are intended to beused as a normal table or view in a SQL statement. They
are also used to pipeline information inan ETL process.26. Name three
advisory statistics you can collect.Buffer Cache Advice, Segment Level
Statistics, & Timed Statistics27. Where in the Oracle directory tree structure
are audit traces placed?In unix $ORACLE_HOME/rdbms/audit, in Windows
the event viewer28. Explain materialized views and how they are
used.Materialized views are objects that are reduced sets of information that
have been summarized,grouped, or aggregated from base tables. They are
typically used in data warehouse or decisionsupport systems.29. When a user
process fails, what background process cleans up after it?PMON30. What
background process refreshes materialized views?The Job Queue
Processes.31. How would you determine what sessions are connected and
what resources they arewaiting for?Use of V$SESSION and
V$SESSION_WAIT32. Describe what redo logs are.Redo logs are logical and
physical structures that are designed to hold all the changes made to
adatabase and are intended to aid in the recovery of a database.33. How would
you force a log switch?ALTER SYSTEM SWITCH LOGFILE;34. Give two
methods you could use to determine what DDL changes have been made.You
could use Logminer or Streams35. What does coalescing a tablespace do?
9. Coalescing is only valid for dictionary-managed tablespaces and de-
fragments space bycombining neighboring free extents into large single
extents.36. What is the difference between a TEMPORARY tablespace and a
PERMANENTtablespace?A temporary tablespace is used for temporary
objects such as sort structures while permanenttablespaces are used to store
those objects meant to be used as the true objects of the database.37. Name a
tablespace automatically created when you create a database.The SYSTEM
tablespace.38. When creating a user, what permissions must you grant to
allow them to connect to thedatabase?Grant the CONNECT to the user.39.
How do you add a data file to a tablespace?ALTER TABLESPACE
<tablespace_name> ADD DATAFILE <datafile_name> SIZE <size>40. How
do you resize a data file?ALTER DATABASE DATAFILE <datafile_name>
RESIZE <new_size>;41. What view would you use to look at the size of a data
file?DBA_DATA_FILES42. What view would you use to determine free space
in a tablespace?DBA_FREE_SPACE43. How would you determine who has
added a row to a table?Turn on fine grain auditing for the table.44. How can
you rebuild an index?ALTER INDEX <index_name> REBUILD;45. Explain
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7. 12/23/12 Dba 3+ exp qus
what partitioning is and what its benefit is.Partitioning is a method of taking
large tables and indexes and splitting them into smaller, moremanageable
pieces.
10. 46. You have just compiled a PL/SQL package but got errors, how would
you view theerrors?SHOW ERRORS47. How can you gather statistics on a
table?The ANALYZE command.48. How can you enable a trace for a session?
Use the DBMS_SESSION.SET_SQL_TRACE orUse ALTER SESSION SET
SQL_TRACE = TRUE;49. What is the difference between the SQL*Loader and
IMPORT utilities?These two Oracle utilities are used for loading data into the
database. The difference is that theimport utility relies on the data being
produced by another Oracle utility EXPORT while theSQL*Loader utility
allows data to be loaded that has been produced by other utilities
fromdifferent data sources just so long as it conforms to ASCII formatted or
delimited files.50. Name two files used for network connection to a
database.TNSNAMES.ORA and SQLNET.ORATechnical - UNIXEvery DBA
should know something about the operating system that the database will be
runningon. The questions here are related to UNIX but you should equally be
able to answer questionsrelated to common Windows environments.1. How
do you list the files in an UNIX directory while also showing hidden files?ls -
ltra2. How do you execute a UNIX command in the background?Use the "&"3.
What UNIX command will control the default file permissions when files are
created?Umask4. Explain the read, write, and execute permissions on a UNIX
directory.
11. Read allows you to see and list the directory contents.Write allows you to
create, edit and delete files and subdirectories in the directory.Execute gives
you the previous read/write permissions plus allows you to change into
thedirectory and execute programs or shells from the directory.5. the difference
between a soft link and a hard link?A symbolic (soft) linked file and the
targeted file can be located on the same or different filesystem while for a hard
link they must be located on the same file system.6. Give the command to
display space usage on the UNIX file system.df -lk7. Explain iostat, vmstat and
netstat.Iostat reports on terminal, disk and tape I/O activity.Vmstat reports on
virtual memory statistics for processes, disk, tape and CPU activity.Netstat
reports on the contents of network data structures.8. How would you change
all occurrences of a value using VI?Use :%s/<old>/<new>/g9. Give two UNIX
kernel parameters that effect an Oracle installSHMMAX & SHMMNI10.
Briefly, how do you install Oracle software on UNIX.Basically, set up disks,
kernel parameters, and run orainst.I hope that these interview questions were
not too hard. Remember these are "core" DBAquestions and not necessarily
related to the Oracle options that you may encounter in someinterviews. Take
a close look at the requirements for any job and try to extract questions
thatinterviewers may ask from manuals and real life experiences. For instance,
if they are looking fora DBA to run their databases in RAC environments, you
should try to determine what hardwareand software they are using BEFORE
you get to the interview. This would allow you to brush upon particular
environments and not be caught off-guard. Good luck!
12. Oracle Technical Interview Questions Answered - Part2james koopmann |
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8. 12/23/12 Dba 3+ exp qus
Nov 3, 2005 | Comments (40)inShare1I promised the second part of this a
couple of weeks ago. Well here it is.Again this is an article I put together a
while back but still get quite a bit of email in its regard. Sothought it might be
of interest to the readers at ITtoolbox.The Oracle Technical Interview can be
quite daunting. You never quite know what to study for and howto prepare. I
am fully aware of this, as I have received many emails since my original article
on interviewquestions was released. While these questions are only
guidelines as to what should and more thanlikely will be asked, I hope that
you find some comfort in the review of them. As always, do not justmemorize
the answers, as there are jewels to be found in the quest of figuring out the
answer from thequestion. As always, remember that as you go through the
article, it is not enough to know the answerto a particular question; you must
try to put yourself in an interview situation and experience answeringthe
question for yourself. Therefore, after you have gone through the questions
and answers read thequestion again and then answer it with your own words.
As always, good luck, and cheers.Technical - OracleLast time, we answered
questions 1 thru 20 of the technical part of the interview. Here are the next 30in
this section. Depending on the mood of the interview and your ability to
elaborate on the answer, tryto give some insight that you know more than just
the simple answer to some of these questions. Also,be sensitive to the
interviewer getting tired of you talking too much. Well here they are.21. How
would you determine the time zone under which a database was operating?
select DBTIMEZONE from dual;22. Explain the use of setting
GLOBAL_NAMES equal to TRUE.Setting GLOBAL_NAMES dictates how
you might connect to a database. This variable is either TRUE orFALSE and if
it is set to TRUE it enforces database links to have the same name as the
remote databaseto which they are linking.23. What command would you use
to encrypt a PL/SQL application?
13. WRAP24. Explain the difference between a FUNCTION, PROCEDURE and
PACKAGE.A function and procedure are the same in that they are intended to
be a collection of PL/SQL code thatcarries a single task. While a procedure
does not have to return any values to the calling application, afunction will
return a single value. A package on the other hand is a collection of functions
andprocedures that are grouped together based on their commonality to a
business function or application.25. Explain the use of table functions.Table
functions are designed to return a set of rows through PL/SQL logic but are
intended to be used asa normal table or view in a SQL statement. They are also
used to pipeline information in an ETL process.26. Name three advisory
statistics you can collect.Buffer Cache Advice, Segment Level Statistics, &
Timed Statistics27. Where in the Oracle directory tree structure are audit traces
placed?In unix $ORACLE_HOME/rdbms/audit, in Windows the event
viewer28. Explain materialized views and how they are used.Materialized views
are objects that are reduced sets of information that have been
summarized,grouped, or aggregated from base tables. They are typically used
in data warehouse or decision supportsystems.29. When a user process fails,
what background process cleans up after it?PMON30. What background
process refreshes materialized views?The Job Queue Processes.31. How
would you determine what sessions are connected and what resources they
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9. 12/23/12 Dba 3+ exp qus
are waiting for?Use of V$SESSION and V$SESSION_WAIT32. Describe what
redo logs are.
14. Redo logs are logical and physical structures that are designed to hold all
the changes made to adatabase and are intended to aid in the recovery of a
database.33. How would you force a log switch?ALTER SYSTEM SWITCH
LOGFILE;34. Give two methods you could use to determine what DDL
changes have been made.You could use Logminer or Streams35. What does
coalescing a tablespace do?Coalescing is only valid for dictionary-managed
tablespaces and de-fragments space by combiningneighboring free extents
into large single extents.36. What is the difference between a TEMPORARY
tablespace and a PERMANENT tablespace?A temporary tablespace is used
for temporary objects such as sort structures while permanenttablespaces are
used to store those objects meant to be used as the true objects of the
database.37. Name a tablespace automatically created when you create a
database.The SYSTEM tablespace.38. When creating a user, what permissions
must you grant to allow them to connect to the database?Grant the CONNECT
to the user.39. How do you add a data file to a tablespace?ALTER
TABLESPACE ADD DATAFILE SIZE40. How do you resize a data file?
ALTER DATABASE DATAFILE RESIZE ;41. What view would you use to
look at the size of a data file?DBA_DATA_FILES42. What view would you
use to determine free space in a tablespace?
15. DBA_FREE_SPACE43. How would you determine who has added a row to
a table?Turn on fine grain auditing for the table.44. How can you rebuild an
index?ALTER INDEX REBUILD;45. Explain what partitioning is and what its
benefit is.Partitioning is a method of taking large tables and indexes and
splitting them into smaller, moremanageable pieces.46. You have just compiled
a PL/SQL package but got errors, how would you view the errors?SHOW
ERRORS47. How can you gather statistics on a table?The ANALYZE
command.48. How can you enable a trace for a session?Use the
DBMS_SESSION.SET_SQL_TRACE orUse ALTER SESSION SET
SQL_TRACE = TRUE;49. What is the difference between the SQL*Loader and
IMPORT utilities?These two Oracle utilities are used for loading data into the
database. The difference is that the importutility relies on the data being
produced by another Oracle utility EXPORT while the SQL*Loader
utilityallows data to be loaded that has been produced by other utilities from
different data sources just solong as it conforms to ASCII formatted or
delimited files.50. Name two files used for network connection to a
database.TNSNAMES.ORA and SQLNET.ORATechnical - UNIX
16. Every DBA should know something about the operating system that the
database will be running on. Thequestions here are related to UNIX but you
should equally be able to answer questions related tocommon Windows
environments.1. How do you list the files in an UNIX directory while also
showing hidden files?ls -ltra2. How do you execute a UNIX command in the
background?Use the "&"3. What UNIX command will control the default file
permissions when files are created?Umask4. Explain the read, write, and
execute permissions on a UNIX directory.Read allows you to see and list the
directory contents.Write allows you to create, edit and delete files and
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10. 12/23/12
subdirectories in the directory.Execute gives you the previous read/write
permissions plus allows you to change into the directory andexecute programs
or shells from the directory.5. the difference between a soft link and a hard
link?A symbolic (soft) linked file and the targeted file can be located on the
same or different file systemwhile for a hard link they must be located on the
same file system.6. Give the command to display space usage on the UNIX file
system.df -lk7. Explain iostat, vmstat and netstat.Iostat reports on terminal,
disk and tape I/O activity.Vmstat reports on virtual memory statistics for
processes, disk, tape and CPU activity.Netstat reports on the contents of
network data structures.
17. 8. How would you change all occurrences of a value using VI?Use
:%s///g9. Give two UNIX kernel parameters that effect an Oracle
installSHMMAX & SHMMNI10. Briefly, how do you install Oracle software
on UNIX.Basically, set up disks, kernel parameters, and run orainst.I hope that
these interview questions were not too hard. Remember these are "core" DBA
questions andnot necessarily related to the Oracle options that you may
encounter in some interviews. Take a closelook at the requirements for any job
and try to extract questions that interviewers may ask frommanuals and real
life experiences. For instance, if they are looking for a DBA to run their
databases inRAC environments, you should try to determine what hardware
and software they are using BEFORE youget to the interview. This would
allow you to brush up on particular environments and not be caught off-
guard. Good luck!
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