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Interview questions for DBA
1.How
many memory layers are in the shared pool?
2.How do you find out from the RMAN catalog if a
particular archive log has been backed-up?
3.How can you tell how much space is left on a given
file system and how much space each of the file system’s
subdirectories take-up?
4.Define the SGA and how you would configure SGA for a
mid-sized OLTP environment? What is involved in tuning
the SGA?
5.What is
the cache hit ratio, what impact does it have on
performance of an Oracle database and what is involved
in tuning it?
Other than making use of the statspack utility, what
would you check when you are monitoring or running a
health check on an Oracle 8i or 9i database?
6.How do you tell what your machine name is and what is
its IP address?
7.How would you go about verifying the network name that
the local_listener is currently using?
8.You have 4 instances running on the same UNIX box. How
can you determine which shared memory and semaphores are
associated with which instance?
9.What view(s) do you use to associate a user’s SQLPLUS
session with his o/s process?
10.What is the recommended interval at which to run
statspack snapshots, and why?
11.What spfile/init.ora file parameter exists to force
the CBO to make the execution path of a given statement
use an index, even if the index scan may appear to be
calculated as more costly?
12.Assuming today is Monday, how would you use the
DBMS_JOB package to schedule the execution of a given
procedure owned by SCOTT to start Wednesday at 9AM and
to run subsequently every other day at 2AM.
13.How would you edit your CRONTAB to schedule the
running of /test/test.sh to run every other day at 2PM?
14.What do the 9i dbms_standard.sql_txt() and
dbms_standard.sql_text() procedures do?
15.In which dictionary table or view would you look to
determine at which time a snapshot or MVIEW last
successfully refreshed?
16.How would you best determine why your MVIEW couldn’t
FAST REFRESH?
17.How does propagation differ between Advanced
Replication and Snapshot Replication (read-only)?
18.Which dictionary view(s) would you first look at to
understand or get a high-level idea of a given Advanced
Replication environment?
19.How would you begin to troubleshoot an ORA-3113
error?
20.Which dictionary tables and/or views would you look
at to diagnose a locking issue?
21.An automatic job running via DBMS_JOB has failed.
Knowing only that “it’s failed’, how do you approach
troubleshooting this issue?
22.How would you extract DDL of a table without using a
GUI tool?
23.You’re getting high “busy buffer waits’ - how can you
find what’s causing it?
24.What query tells you how much space a tablespace
named “test’ is taking up, and how much space is
remaining?
25.Database is hung. Old and new user connections alike
hang on impact. What do you do? Your SYS SQLPLUS session
IS able to connect.
26.Database crashes. Corruption is found scattered among
the file system neither of your doing nor of Oracle’s.
What database recovery options are available? Database
is in archive log mode.
27.Illustrate how to determine the amount of physical
CPUs a Unix Box possesses (LINUX and/or Solaris).
28.How do you increase the OS limitation for open files
(LINUX and/or Solaris)?
29.Provide an example of a shell script which logs into
SQLPLUS as SYS, determines the current date, changes the
date format to include minutes & seconds, issues a drop
table command, displays the date again, and finally
exits.
30.Explain how you would restore a database using RMAN
to Point in Time?
31.How does Oracle guarantee data integrity of data
changes?
32.Which environment variables are absolutely critical
in order to run the OUI?
33.What SQL query from v$session can you run to show how
many sessions are logged in as a particular user
account?
34.Why does Oracle not permit the use of PCTUSED with
indexes?
35.What would you use to improve performance on an
insert statement that places millions of rows into that
table?
36.What would you do with an “in-doubt” distributed
transaction?
37.What are the commands you’d issue to show the explain
plan for “select * from dual’?
38.In what script is “snap$” created? In what script is
the “scott/tiger” schema created?
39.If you’re unsure in which script a sys or
system-owned object is created, but you know it’s in a
script from a specific directory, what UNIX command from
that directory structure can you run to find your
answer?
40.How would you configure your networking files to
connect to a database by the name of DSS which resides
in domain icallinc.com?
41.You create a private database link and upon
connection, fails with: ORA-2085: connects to . What is
the problem? How would you go about resolving this
error?
42.I have my backup RMAN script called “backup_rman.sh”.
I am on the target database. My catalog
username/password is rman/rman. My catalog db is called
rman. How would you run this shell script from the O/S
such that it would run as a background process?
43.Explain the concept of the DUAL table.
44.What are the ways tablespaces can be managed and how
do they differ?
45.From the database level, how can you tell under which
time zone a database is operating?
46.What’s the benefit of “dbms_stats” over “analyze”?
47.Typically, where is the conventional directory
structure chosen for Oracle binaries to reside?
48.You have found corruption in a tablespace that
contains static tables that are part of a database that
is in NOARCHIVE log mode. 49.How would you restore the
tablespace without losing new data in the other
tablespaces?
50.How do you recover a datafile that has not been
physically been backed up since its creation and has
been deleted. Provide syntax example.
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