General Questions
§ Tell us about yourself/ your background.
§ What are the three major characteristics that
you bring to the job market?
§ What motivates you to do a good job?
§ What two or three things are most important to
you at work?
§ What qualities do you think are essential to be
successful in this kind of work?
§ What courses did you attend? What job
certifications do you hold?
§ What subjects/courses did you excel in? Why?
§ What subjects/courses gave you trouble? Why?
§ How does your previous work experience prepare
you for this position?
§ How do you define 'success'?
§ What has been your most significant
accomplishment to date?
§ Describe a challenge you encountered and how you
dealt with it.
§ Describe a failure and how you dealt with it.
§ Describe the 'ideal' job... the 'ideal'
supervisor.
§ What leadership roles have you held?
§ What prejudices do you hold?
§ What do you like to do in your spare time?
§ What are your career goals (a) 3 years from now;
(b) 10 years from now?
§ How does this position match your career goals?
§ What have you done in the past year to improve
yourself?
§ In what areas do you feel you need further
education and training to be successful?
§ What do you know about our company?
§ Why do you want to work for this company. Why
should we hire you?
§ Where do you see yourself fitting in to this
organization ...initially? ...in 5 years?
§ Why are you looking for a new job?
§ How do you feel about re-locating?
§ Are you willing to travel?
§ What are your salary requirements?
§ When would you be available to start if you were
selected?
Here are few interview questions with answers found on the internet. As I don't have time to format these questions to wiki I am just posting them hoping someone to format them.
1. Explain the
difference between a hot backup and a cold backup and the benefits associated
with each.
A hot backup is
basically taking a backup of the database while it is still up and running and
it must be in archive log mode. A cold backup is taking a backup of the
database while it is shut down and does not require being in archive log mode.
The benefit of taking a hot backup is that the database is still available for
use while the backup is occurring and you can recover the database to any point
in time. The benefit of taking a cold backup is that it is typically easier to
administer the backup and recovery process. In addition, since you are taking
cold backups the database does not require being in archive log mode and thus
there will be a slight performance gain as the database is not cutting archive
logs to disk.
2. You have just had
to restore from backup and do not have any control files. How would you go
about bringing up this database?
I would create a text
based backup control file, stipulating where on disk all the data files were
and then issue the recover command with the using backup control file clause.
3. How do you switch
from an init.ora file to a spfile?
Issue the create spfile
from pfile command.
4. Explain the
difference between a data block, an extent and a segment.
A data block is the
smallest unit of logical storage for a database object. As objects grow they
take chunks of additional storage that are composed of contiguous data blocks.
These groupings of contiguous data blocks are called extents. All the extents
that an object takes when grouped together are considered the segment of the
database object.
5. Give two examples
of how you might determine the structure of the table DEPT.
Use the describe command
or use the dbms_metadata.get_ddl package.
6. Where would you
look for errors from the database engine?
In the alert log.
7. Compare and
contrast TRUNCATE and DELETE for a table.
Both the truncate and
delete command have the desired outcome of getting rid of all the rows in a
table. The difference between the two is that the truncate command is a DDL operation
and just moves the high water mark and produces few rollback data. The delete
command, on the other hand, is a DML operation, which will produce rollback
data and thus take longer to complete.
8. Give the reasoning
behind using an index.
Faster access to data
blocks in a table.
9. Give the two types
of tables involved in producing a star schema and the type of data they hold.
Fact tables and
dimension tables. A fact table contains measurements while dimension tables
will contain data that will help describe the fact tables.
10. What type of
index should you use on a fact table?
11. Give some
examples of the types of database contraints you may find in Oracle and
indicate their purpose.
A Primary or Unique Key
can be used to enforce uniqueness on one or more columns.
A Referential Integrity
Contraint can be used to enforce a Foreign Key relationship between two tables.
A Not Null constraint -
to ensure a value is entered in a column
A Value Constraint - to
check a column value against a specific set of values.
12. A table is
classified as a parent table and you want to drop and re-create it. How would
you do this without affecting the children tables?
Disable the foreign key
constraint to the parent, drop the table, re-create the table, enable the
foreign key constraint.
13. Explain the
difference between ARCHIVELOG mode and NOARCHIVELOG mode and the benefits and
disadvantages to each.
ARCHIVELOG mode is a
mode that you can put the database in for creating a backup of all transactions
that have occurred in the database so that you can recover to any point in
time. NOARCHIVELOG mode is basically the absence of ARCHIVELOG mode and has the
disadvantage of not being able to recover to any point in time. NOARCHIVELOG
mode does have the advantage of not having to write transactions to an archive
log and thus increases the performance of the database slightly.
14. What command
would you use to create a backup control file?
Alter database backup
control file to trace.
15. Give the stages
of instance startup to a usable state where normal users may access it.
STARTUP NOMOUNT -
Instance startup
STARTUP MOUNT - The
database is mounted
STARTUP OPEN - The
database is opened
16. What column
differentiates the V$ views to the GV$ views and how?
The INST_ID column which
indicates the instance in a RAC environment the information came from.
17. How would you go
about generating an EXPLAIN plan?
Create a plan table with
utlxplan.sql.
Use the explain plan set
statement_id = 'tst1' into plan_table for a SQL statement
Look at the explain plan
with utlxplp.sql or utlxpls.sql
18. How would you go
about increasing the buffer cache hit ratio?
Use the buffer cache
advisory over a given workload and then query the v$db_cache_advice table. If a
change was necessary then I would use the alter system set db_cache_size
command.
You get this error when you get a snapshot too old
within rollback. It can usually be solved by increasing the undo retention or
increasing the size of rollbacks. You should also look at the logic involved in
the application getting the error message.
20. Explain the
difference between $ORACLE_HOME and $ORACLE_BASE.
ORACLE_BASE is the root directory for oracle. ORACLE_HOME located
beneath ORACLE_BASE is where the oracle products reside.
1. How would you
determine the time zone under which a database was operating?
SELECT dbtimezone FROM DUAL;
2. Explain the use of
setting GLOBAL_NAMES equal to TRUE.
It ensure the use of consistent naming conventions for databases
and links in a networked environment.
3. What command would
you use to encrypt a PL/SQL application?
WRAP
4. Explain the difference
between a FUNCTION, PROCEDURE and PACKAGE.
They are all named PL/SQL blocks.
Function must return a value. Can be called inside a query.
Procedure may or may not return value.
Package is the collection of functions, procedures, variables
which can be logically grouped together.
5. Explain the use of
table functions.
6. Name three advisory
statistics you can collect.
7. Where in the Oracle
directory tree structure are audit traces placed?
8. Explain materialized
views and how they are used.
9. When a user process
fails, what background process cleans up after it?
PMON
10. What background
process refreshes materialized views?
Job Queue Process (CJQ)
11. How would you
determine what sessions are connected and what resources they are waiting for?
v$session,v$session_wait
12. Describe what redo
logs are.
13. How would you force
a log switch?
alter system switch logfile;
14. Give two methods you
could use to determine what DDL changes have been made.
15. What does coalescing
a tablespace do?
Coalesce simply takes contigous free extents and makes them into a
single bigger free extent.
16. What is the
difference between a TEMPORARY tablespace and a PERMANENT tablespace?
TEMP tablespace gets cleared once the transaction is done where as
PERMANENT tablespace retails the data.
17. Name a tablespace
automatically created when you create a database.
SYSTEM
18. When creating a
user, what permissions must you grant to allow them to connect to the database?
Grant create session to username;
19. How do you add a
data file to a tablespace?
alter tablespace USERS add datafile '/ora01/oradata/users02.dbf'
size 50M;
20. How do you resize a
data file?
alter database datafile '/ora01/oradata/users02.dbf' resize 100M;
21. What view would you
use to look at the size of a data file?
dba_data_files
22. What view would you
use to determine free space in a tablespace?
dba_free_space
23. How would you
determine who has added a row to a table?
By implementing an INSERT trigger for logging details during each
INSERT operation on the table
24. How can you rebuild
an index?
ALTER INDEX index_name REBUILD;
25. Explain what
partitioning is and what its benefit is.
A table partition is also a table segment, and by using
partitioning technique we can enhance performance of table access.
26. You have just
compiled a PL/SQL package but got errors, how would you view the errors?
show errors
27. How can you gather
statistics on a table?
exec dbms_stats.gather_table_stats
Also, remember to analyze all associated indexes on that table
using dbms_stats.gather_index_stats
28. How can you enable a
trace for a session?
alter session set sql_trace='TRUE';
29. What is the
difference between the SQL*Loader and IMPORT utilities?
SQL*LOADER loads external data which is in OS files to oracle
database tables while IMPORT utility imports data only which is exported by
EXPORT utility of oracle database.
30. Name two files used
for network connection to a database.
TNSNAMES.ORA and SQLNET.ORA
1. Describe the
difference between a procedure, function and anonymous pl/sql block. Candidate should mention use of DECLARE
statement, a function must return a value while a procedure doesn't have to.
2. What is a mutating
table error and how can you get around it? This happens with triggers. It occurs because the trigger is
trying to update a row it is currently using. The usual fix involves either use
of views or temporary tables so the database is selecting from one while
updating the other.
3. Describe the use
of %ROWTYPE and %TYPE in PL/SQL Expected answer: %ROWTYPE allows you to
associate a variable with an entire table row. The %TYPE associates a
variable with a single column type.
4. What packages (if
any) has Oracle provided for use by developers? Expected answer: Oracle provides the DBMS_
series of packages. There are many which developers should be aware of such as
DBMS_SQL, DBMS_PIPE, DBMS_TRANSACTION, DBMS_LOCK, DBMS_ALERT, DBMS_OUTPUT,
DBMS_JOB, DBMS_UTILITY, DBMS_DDL, UTL_FILE. If they can mention a few of these
and describe how they used them, even better. If they include the SQL routines
provided by Oracle, great, but not really what was asked.
5. Describe the use of
PL/SQL tables Expected answer:
PL/SQL tables are scalar arrays that can be referenced by a binary integer.
They can be used to hold values for use in later queries or calculations. In
Oracle 8 they will be able to be of the %ROWTYPE designation, or RECORD.
6. When is a declare
statement needed ? The
DECLARE statement is used in PL/SQL anonymous blocks such as with stand alone,
non-stored PL/SQL procedures. It must come first in a PL/SQL stand alone file
if it is used.
7. In what order should
a open/fetch/loop set of commands in a PL/SQL block be implemented if you use
the %NOTFOUND cursor variable in the exit when statement? Why? Expected answer: OPEN then FETCH then LOOP
followed by the exit when. If not specified in this order will result in the
final return being done twice because of the way the %NOTFOUND is handled
by PL/SQL.
8. What are SQLCODE and
SQLERRM and why are they important for PL/SQL developers? Expected answer: SQLCODE returns the value
of the error number for the last error encountered. The SQLERRM returns the
actual error message for the last error encountered. They can be used in
exception handling to report, or, store in an error log table, the error that
occurred in the code. These are especially useful for the WHEN OTHERS
exception.
9. How can you find
within a PL/SQL block, if a cursor is open? Expected answer: Use the %ISOPEN cursor status
variable.
10. How can you generate
debugging output from PL/SQL? Expected answer: Use the DBMS_OUTPUT package. Another
possible method is to just use the SHOW ERROR command, but this only shows
errors. The DBMS_OUTPUT package can be used to show intermediate results from
loops and the status of variables as the procedure is executed. The new package
UTL_FILE can also be used.
11. What are the types of triggers? Expected Answer: There are 12 types of
triggers in PL/SQL that consist of combinations of the BEFORE, AFTER, ROW,
TABLE, INSERT, UPDATE, DELETE and ALL key words: BEFORE ALL ROW INSERT AFTER
ALL ROW INSERT BEFORE INSERT AFTER INSERT etc.
1. A tablespace has a
table with 30 extents in it. Is this bad? Why or why not.
Multiple extents in and
of themselves aren?t bad. However if you also have chained rows this can hurt
performance.
2. How do you set up
tablespaces during an Oracle installation?
You should always
attempt to use the Oracle Flexible Architecture standard or another
partitioning scheme to ensure proper separation of SYSTEM, ROLLBACK, REDO LOG,
DATA, TEMPORARY and INDEX segments.
3. You see multiple
fragments in the SYSTEM tablespace, what should you check first?
Ensure that users don?t
have the SYSTEM tablespace as their TEMPORARY or DEFAULT tablespace assignment
by checking the DBA_USERS view.
4. What are some
indications that you need to increase the SHARED_POOL_SIZE parameter?
Poor data dictionary or
library cache hit ratios, getting error ORA-04031. Another indication is
steadily decreasing performance with all other tuning parameters the same.
5. What is the general
guideline for sizing db_block_size and db_multi_block_read for an application
that does many full table scans?
Oracle almost always
reads in 64k chunks. The two should have a product equal to 64 or a multiple of
64.
6. What is the fastest
query method for a table
Fetch by rowid
7. Explain the use of
TKPROF? What initialization parameter should be turned on to get full TKPROF
output?
The tkprof tool is a
tuning tool used to determine cpu and execution times for SQL statements. You
use it by first setting timed_statistics to true in the initialization file and
then turning on tracing for either the entire database via the sql_trace
parameter or for the session using the ALTER SESSION command. Once the trace
file is generated you run the tkprof tool against the trace file and then look
at the output from the tkprof tool. This can also be used to generate explain
plan output.
8. When looking at
v$sysstat you see that sorts (disk) is high. Is this bad or good? If bad -How
do you correct it?
If you get excessive
disk sorts this is bad. This indicates you need to tune the sort area
parameters in the initialization files. The major sort are parameter is the
SORT_AREA_SIZe parameter.
9. When should you
increase copy latches? What parameters control copy latches
When you get excessive
contention for the copy latches as shown by the "redo copy" latch hit
ratio. You can increase copy latches via the initialization parameter
LOG_SIMULTANEOUS_COPIES to twice the number of CPUs on your system.
10. Where can you get a
list of all initialization parameters for your instance? How about an
indication if they are default settings or have been changed
You can look in the
init.ora file for an indication of manually set parameters. For all parameters,
their value and whether or not the current value is the default value, look in
the v$parameter view.
11. Describe hit ratio
as it pertains to the database buffers. What is the difference between
instantaneous and cumulative hit ratio and which should be used for tuning
The hit ratio is a
measure of how many times the database was able to read a value from the
buffers verses how many times it had to re-read a data value from the disks. A
value greater than 80-90% is good, less could indicate problems. If you simply
take the ratio of existing parameters this will be a cumulative value since the
database started. If you do a comparison between pairs of readings based on
some arbitrary time span, this is the instantaneous ratio for that time span.
Generally speaking an instantaneous reading gives more valuable data since it
will tell you what your instance is doing for the time it was generated over.
12. Discuss row
chaining, how does it happen? How can you reduce it? How do you correct it
Row chaining occurs when a VARCHAR2 value is updated and the
length of the new value is longer than the old value and won?t fit in the
remaining block space. This results in the row chaining to another block. It
can be reduced by setting the storage parameters on the table to appropriate
values. It can be corrected by export and import of the effected table.
1. Give one method for
transferring a table from one schema to another:
There are several
possible methods, export-import, CREATE TABLE... AS SELECT, or COPY.
2. What is the purpose
of the IMPORT option IGNORE? What is it?s default setting
The IMPORT IGNORE option
tells import to ignore "already exists" errors. If it is not
specified the tables that already exist will be skipped. If it is specified,
the error is ignored and the tables data will be inserted. The default value is
N.
3. You have a rollback
segment in a version 7.2 database that has expanded beyond optimal, how can it
be restored to optimal
Use the ALTER TABLESPACE
..... SHRINK command.
4. If the DEFAULT and
TEMPORARY tablespace clauses are left out of a CREATE USER command what
happens? Is this bad or good? Why
The user is assigned the
SYSTEM tablespace as a default and temporary tablespace. This is bad because it
causes user objects and temporary segments to be placed into the SYSTEM
tablespace resulting in fragmentation and improper table placement (only data
dictionary objects and the system rollback segment should be in SYSTEM).
5. What are some of the
Oracle provided packages that DBAs should be aware of
Oracle provides a number
of packages in the form of the DBMS_ packages owned by the SYS user. The
packages used by DBAs may include: DBMS_SHARED_POOL, DBMS_UTILITY, DBMS_SQL,
DBMS_DDL, DBMS_SESSION, DBMS_OUTPUT and DBMS_SNAPSHOT. They may also try to
answer with the UTL*.SQL or CAT*.SQL series of SQL procedures. These can be
viewed as extra credit but aren?t part of the answer.
6. What happens if the
constraint name is left out of a constraint clause
The Oracle system will
use the default name of SYS_Cxxxx where xxxx is a system generated number. This
is bad since it makes tracking which table the constraint belongs to or what
the constraint does harder.
7. What happens if a
tablespace clause is left off of a primary key constraint clause
This results in the index
that is automatically generated being placed in then users default tablespace.
Since this will usually be the same tablespace as the table is being created
in, this can cause serious performance problems.
8. What is the proper
method for disabling and re-enabling a primary key constraint
You use the ALTER TABLE
command for both. However, for the enable clause you must specify the USING
INDEX and TABLESPACE clause for primary keys.
9. What happens if a
primary key constraint is disabled and then enabled without fully specifying
the index clause
The index is created in
the user?s default tablespace and all sizing information is lost. Oracle
doesn?t store this information as a part of the constraint definition, but only
as part of the index definition, when the constraint was disabled the index was
dropped and the information is gone.
10. (On UNIX) When
should more than one DB writer process be used? How many should be used
If the UNIX system being
used is capable of asynchronous IO then only one is required, if the system is
not capable of asynchronous IO then up to twice the number of disks used by
Oracle number of DB writers should be specified by use of the db_writers
initialization parameter.
11. You are using hot
backup without being in archivelog mode, can you recover in the event of a
failure? Why or why not
You can?t use hot backup
without being in archivelog mode. So no, you couldn?t recover.
12. What causes the
"snapshot too old" error? How can this be prevented or mitigated
This is caused by large or
long running transactions that have either wrapped onto their own rollback
space or have had another transaction write on part of their rollback space.
This can be prevented or mitigated by breaking the transaction into a set of
smaller transactions or increasing the size of the rollback segments and their
extents.
13. How can you tell if a database object is invalid By checking
the status column of the DBA_, ALL_ or USER_OBJECTS views, depending upon
whether you own or only have permission on the view or are using a DBA account.
|
1. How can variables
be passed to a SQL routine
|
|
By use of the &
symbol. For passing in variables the numbers 1-8 can be used (&1,
&2,...,&8) to pass the values after the command into the SQLPLUS
session. To be prompted for a specific variable, place the ampersanded
variable in the code itself: "select * from dba_tables where
owner=&owner_name;" . Use of double ampersands tells SQLPLUS to
resubstitute the value for each subsequent use of the variable, a single
ampersand will cause a reprompt for the value unless an ACCEPT statement is
used to get the value from the user.
|
|
2. You want to include
a carriage return/linefeed in your output from a SQL script, how can you do
this
|
|
The best method is to
use the CHR() function (CHR(10) is a return/linefeed) and the concatenation
function "||". Another method, although it is hard to document and
isn?t always portable is to use the return/linefeed as a part of a quoted
string.
|
|
3. How can you call a
PL/SQL procedure from SQL
|
|
By use of the EXECUTE
(short form EXEC) command.
|
|
4. How do you execute
a host operating system command from within SQL
|
|
By use of the
exclamation ball "!" (in UNIX and some other OS) or the HOST (HO)
command.
|
|
5. You want to use SQL
to build SQL, what is this called and give an example
|
|
This is called dynamic
SQL. An example would be: set lines 90 pages 0 termout off feedback off
verify off spool drop_all.sql select ?drop user ?||username||?
cascade;? from dba_users where username not in ("SYS?,?SYSTEM?); spool
off Essentially you are looking to see that they know to include a command
(in this case DROP USER...CASCADE;) and that you need to concatenate using
the ?||? the values selected from the database.
|
|
6. What SQLPlus
command is used to format output from a select
|
|
This is best done with
the COLUMN command.
|
|
7. You want to group
the following set of select returns, what can you group on
|
|
Max(sum_of_cost),
min(sum_of_cost), count(item_no), item_no The only column that can be grouped
on is the "item_no" column, the rest have aggregate functions
associated with them.
|
|
8. What special Oracle
feature allows you to specify how the cost based system treats a SQL
statement
|
|
The COST based system
allows the use of HINTs to control the optimizer path selection. If they can
give some example hints such as FIRST ROWS, ALL ROWS, USING INDEX, STAR, even
better.
|
|
9. You want to
determine the location of identical rows in a table before attempting to
place a unique index on the table, how can this be done
|
|
Oracle tables always
have one guaranteed unique column, the rowid column. If you use a min/max
function against your rowid and then select against the proposed primary key
you can squeeze out the rowids of the duplicate rows pretty quick. For
example: select rowid from emp e where e.rowid > (select min(x.rowid) from
emp x where x.emp_no = e.emp_no); In the situation where multiple columns
make up the proposed key, they must all be used in the where clause.
|
|
10. What is a
Cartesian product
|
|
A Cartesian product is
the result of an unrestricted join of two or more tables. The result set of a
three table Cartesian product will have x * y * z number of rows where x, y,
z correspond to the number of rows in each table involved in the join.
|
|
11. You are joining a
local and a remote table, the network manager complains about the traffic
involved, how can you reduce the network traffic Push the processing of the
remote data to the remote instance by using a view to pre-select the
information for the join. This will result in only the data required for the
join being sent across.
|
|
11. What is the
default ordering of an ORDER BY clause in a SELECT statement
|
|
Ascending
|
|
12. What is tkprof and
how is it used
|
|
The tkprof tool is a
tuning tool used to determine cpu and execution times for SQL statements. You
use it by first setting timed_statistics to true in the initialization file
and then turning on tracing for either the entire database via the sql_trace
parameter or for the session using the ALTER SESSION command. Once the trace
file is generated you run the tkprof tool against the trace file and then
look at the output from the tkprof tool. This can also be used to generate
explain plan output.
|
|
13. What is explain
plan and how is it used
|
|
The EXPLAIN PLAN
command is a tool to tune SQL statements. To use it you must have an
explain_table generated in the user you are running the explain plan for.
This is created using the utlxplan.sql script. Once the explain plan table
exists you run the explain plan command giving as its argument the SQL
statement to be explained. The explain_plan table is then queried to see the
execution plan of the statement. Explain plans can also be run using tkprof.
|
|
14. How do you set the
number of lines on a page of output? The width
|
|
The SET command in
SQLPLUS is used to control the number of lines generated per page and the
width of those lines, for example SET PAGESIZE 60 LINESIZE 80 will generate
reports that are 60 lines long with a line width of 80 characters. The
PAGESIZE and LINESIZE options can be shortened to PAGES and LINES.
|
|
15. How do you prevent
output from coming to the screen
|
|
The SET option TERMOUT
controls output to the screen. Setting TERMOUT OFF turns off screen output.
This option can be shortened to TERM.
|
|
16. How do you prevent
Oracle from giving you informational messages during and after a SQL
statement execution
|
|
The SET options
FEEDBACK and VERIFY can be set to OFF.
|
|
17. How do you
generate file output from SQL
|
|
By use of the SPOOL
comm
|
|
Oracle Interview
Questions
|
|
1. What is a
CO-RELATED SUBQUERY
|
|
A CO-RELATED SUBQUERY
is one that has a correlation name as table or view designator in the FROM
clause of the outer query and the same correlation name as a qualifier of a
search condition in the WHERE clause of the subquery. eg
|
|
SELECT field1 from table1 X
|
|
WHERE field2>(select
avg(field2) from table1 Y
|
|
where
|
|
field1=X.field1);
|
|
(The subquery in a
correlated subquery is revaluated for every row of the table or view named in
the outer query.)
|
|
2. What are various
joins used while writing SUBQUERIES
|
|
Self join-Its a join
foreign key of a table references the same table.
|
|
Outer Join--Its a join
condition used where One can query all the rows of one of the tables in the
join condition even though they don't satisfy the join condition.
|
|
Equi-join--Its a join
condition that retrieves rows from one or more tables in which one or more
columns in one table are equal to one or more columns in the second table.
|
|
3. What are various
constraints used in SQL
|
|
NULL NOT NULL CHECK
DEFAULT
|
|
4. What are different
Oracle database objects
|
|
TABLES VIEWS INDEXES
SYNONYMS SEQUENCES TABLESPACES etc
|
|
5. What is difference
between Rename and Alias
|
|
Rename is a permanent
name given to a table or column whereas Alias is a temporary name given to a
table or column which do not exist once the SQL statement is executed.
|
|
6. What is a view
|
|
A view is stored
procedure based on one or more tables, its a virtual table.
|
|
7. What are various
privileges that a user can grant to another user
|
|
SELECT CONNECT
RESOURCE
|
|
8. What is difference
between UNIQUE and PRIMARY KEY constraints
|
|
A table can have only
one PRIMARY KEY whereas there can be any number of UNIQUE keys. The columns
that compose PK are automatically define NOT NULL, whereas a column that
compose a UNIQUE is not automatically defined to be mandatory must also
specify the column is NOT NULL.
|
|
9. Can a primary key
contain more than one columns
|
|
Yes
|
|
10. How you will avoid
duplicating records in a query
|
|
By using DISTINCT
|
|
11. What is difference
between SQL and SQL*PLUS
|
|
SQL*PLUS is a command
line tool where as SQL and PL/SQL language interface and reporting tool. Its
a command line tool that allows user to type SQL commands to be executed
directly against an Oracle database. SQL is a language used to query the
relational database(DML,DCL,DDL). SQL*PLUS commands are used to format query
result, Set options, Edit SQL commands and PL/SQL.
|
|
12. Which datatype is
used for storing graphics and images
|
|
LONG RAW data type is
used for storing BLOB's (binary large objects).
|
|
13. How will you
delete duplicating rows from a base table
|
|
DELETE FROM table_name
A WHERE rowid>(SELECT min(rowid) from table_name B where B.table_no=A.table_no);
|
|
CREATE TABLE new_table AS SELECT DISTINCT *
FROM old_table;
|
|
DROP old_table RENAME
new_table TO old_table DELETE FROM table_name A WHERE rowid NOT IN (SELECT
MAX(ROWID) FROM table_name GROUP BY column_name)
|
|
14. What is difference
between SUBSTR and INSTR
|
|
SUBSTR returns a
specified portion of a string eg SUBSTR('BCDEF',4) output BCDE INSTR provides
character position in which a pattern is found in a string.
|
|
eg
INSTR('ABC-DC-F','-',2) output 7 (2nd occurence of '-')
|
|
15. There is a string
'120000 12 0 .125' ,how you will find the position of the decimal place
|
|
INSTR('120000 12 0 .125','.',1) output 13
|
|
16. There is a '%'
sign in one field of a column. What will be the query to find it.
|
|
'\' Should be used
before '%'.
|
|
17. When you use WHERE
clause and when you use HAVING clause
|
|
HAVING clause is used
when you want to specify a condition for a group function and it is written
after GROUP BY clause The WHERE clause is used when you want to specify a
condition for columns, single row functions except group functions and it is
written before GROUP BY clause if it is used.
|
|
18. Which is more
faster - IN or EXISTS
|
|
EXISTS is more faster
than IN because EXISTS returns a Boolean value whereas IN returns a value.
|
|
Appropriate answer
will be....
|
|
Result of the subquery
is small Then "IN" is typicaly more appropriate. and Result of the
subquery is big/large/long Then "EXIST" is more appropriate.
|
|
19. What is a OUTER
JOIN
|
|
Outer Join--Its a join
condition used where you can query all the rows of one of the tables in the
join condition even though they dont satisfy the join condition.
|
|
20. How you will avoid
your query from using indexes
|
|
SELECT * FROM emp
Where emp_no+' '=12345;
|
|
i.e you have to
concatenate the column name with space within codes in the where condition.
|
|
SELECT /*+ FULL(a) */
ename, emp_no from emp where emp_no=1234;
|
|
i.e using HINTS
|
|
Oracle Interview
Questions
|
|
1. What is a pseudo
column. Give some examples
|
|
It is a column that is
not an actual column in the table.
|
|
eg USER, UID, SYSDATE,
ROWNUM, ROWID, NULL, AND LEVEL.
|
|
Suppose customer table
is there having different columns like customer no, payments.What will be the
query to select top three max payments.
|
|
2. What is the purpose
of a cluster.
|
|
Oracle does not allow
a user to specifically locate tables, since that is a part of the function of
the RDBMS. However, for the purpose of increasing performance, oracle allows
a developer to create a CLUSTER. A CLUSTER provides a means for storing data
from different tables together for faster retrieval than if the table
placement were left to the RDBMS.
|
|
3. What is a cursor.
|
|
Oracle uses work area
to execute SQL statements and store processing information PL/SQL construct
called a cursor lets you name a work area and access its stored information A
cursor is a mechanism used to fetch more than one row in a Pl/SQl block.
|
|
4. Difference between
an implicit & an explicit cursor.
|
|
PL/SQL declares a
cursor implicitly for all SQL data manipulation statements, including quries
that return only one row. However,queries that return more than one row you
must declare an explicit cursor or use a cursor FOR loop.
|
|
Explicit cursor is a
cursor in which the cursor name is explicitly assigned to a SELECT statement
via the CURSOR...IS statement. An implicit cursor is used for all SQL
statements Declare, Open, Fetch, Close. An explicit cursors are used to
process multirow SELECT statements An implicit cursor is used to process
INSERT, UPDATE, DELETE and single row SELECT. .INTO statements.
|
|
5. What are cursor
attributes
|
|
%ROWCOUNT %NOTFOUND
%FOUND %ISOPEN
|
|
6. What is a cursor for
loop.
|
|
Cursor For Loop is a
loop where oracle implicitly declares a loop variable, the loop index that of
the same record type as the cursor's record.
|
|
7. Difference between
NO DATA FOUND and %NOTFOUND
|
|
NO DATA FOUND is an
exception raised only for the SELECT....INTO statements when the where clause
of the querydoes not match any rows. When the where clause of the explicit
cursor does not match any rows the %NOTFOUND attribute is set to TRUE
instead.
|
|
8. What a SELECT FOR
UPDATE cursor represent.
|
|
SELECT......FROM......FOR......UPDATE[OF
column-reference][NOWAIT] The processing done in a fetch loop modifies the
rows that have been retrieved by the cursor. A convenient way of modifying
the rows is done by a method with two parts: the FOR UPDATE clause in the
cursor declaration, WHERE CURRENT OF CLAUSE in an UPDATE or declaration
statement.
|
|
9. What 'WHERE CURRENT
OF ' clause does in a cursor.
|
|
LOOP
|
|
SELECT num_credits
INTO v_numcredits FROM classes
|
|
WHERE dept=123 and course=101;
|
|
UPDATE students
|
|
SET
current_credits=current_credits+v_numcredits
|
|
WHERE CURRENT OF
X;
|
|
END LOOP
|
|
COMMIT;
|
|
END;
|
|
10. What is use of a
cursor variable? How it is defined.
|
|
A cursor variable is
associated with different statements at run time, which can hold different
values at run time. Static cursors can only be associated with one run time
query. A cursor variable is reference type(like a pointer in C). Declaring a
cursor variable: TYPE type_name IS REF CURSOR RETURN return_type type_name is
the name of the reference type,return_type is a record type indicating the
types of the select list that will eventually be returned by the cursor
variable.
|
|
11. What should be the
return type for a cursor variable.Can we use a scalar data type as return
type.
|
|
The return type for a
cursor must be a record type.It can be declared explicitly as a user-defined
or %ROWTYPE can be used. eg TYPE t_studentsref IS REF CURSOR RETURN
students%ROWTYPE
|
|
12. How you open and
close a cursor variable.Why it is required.
|
|
OPEN cursor variable
FOR SELECT...Statement CLOSE cursor variable In order to associate a cursor
variable with a particular SELECT statement OPEN syntax is used.In order to
free the resources used for the query CLOSE statement is used.
|
|
13. How you were
passing cursor variables in PL/SQL 2.2.
|
|
In PL/SQL 2.2 cursor
variables cannot be declared in a package.This is because the storage for a
cursor variable has to be allocated using Pro*C or OCI with version 2.2,the
only means of passing a cursor variable to a PL/SQL block is via bind
variable or a procedure parameter.
|
|
14. Can cursor variables
be stored in PL/SQL tables.If yes how.If not why.
|
|
No, a cursor variable
points a row which cannot be stored in a two-dimensional PL/SQL table.
|
|
15. Difference between
procedure and function.
|
|
Functions are named
PL/SQL blocks that return a value and can be called with arguments procedure
a named block that can be called with parameter. A procedure all is a PL/SQL
statement by itself, while a Function call is called as part of an
expression.
|
|
16. What are different
modes of parameters used in functions and procedures.
|
|
IN OUT INOUT
|
|
17. What is difference
between a formal and an actual parameter
|
|
The variables declared
in the procedure and which are passed, as arguments are called actual, the
parameters in the procedure declaration. Actual parameters contain the values
that are passed to a procedure and receive results. Formal parameters are the
placeholders for the values of actual parameters
|
|
18. Can the default
values be assigned to actual parameters.
|
|
Yes
|
|
19. Can a function
take OUT parameters.If not why.
|
|
Yes. A function return
a value, but can also have one or more OUT parameters. it is best practice,
however to use a procedure rather than a function if you have multiple values
to return.
|
|
20. What is syntax for
dropping a procedure and a function .Are these operations possible.
|
|
Drop Procedure procedure_name
|
|
Drop Function function_name
|
|
21. What are ORACLE
PRECOMPILERS.
|
|
Using ORACLE
PRECOMPILERS ,SQL statements and PL/SQL blocks can be contained inside 3GL
programs written in C,C++,COBOL,PASCAL, FORTRAN,PL/1 AND ADA. The
Precompilers are known as Pro*C,Pro*Cobol,... This form of PL/SQL is known as
embedded pl/sql,the language in which pl/sql is embedded is known as the host
language. The prcompiler translates the embedded SQL and pl/sql ststements
into calls to the precompiler runtime library.The output must be compiled and
linked with this library to creater an executable.
|
|
22. What is OCI. What
are its uses.
|
|
Oracle Call Interface
is a method of accesing database from a 3GL program. Uses--No precompiler is
required,PL/SQL blocks are executed like other DML statements.
|
|
The OCI library provides
|
|
-functions to parse SQL
statemets
|
|
-bind input variables
|
|
-bind output variables
|
|
-execute statements
|
|
-fetch the results
|
|
23. Difference between
database triggers and form triggers.
|
|
a) Data base
trigger(DBT) fires when a DML operation is performed on a data base
table.Form trigger(FT) Fires when user presses a key or navigates between
fields on the screen b) Can be row level or statement level No distinction
between row level and statement level. c) Can manipulate data stored in
Oracle tables via SQL Can manipulate data in Oracle tables as well as
variables in forms. d) Can be fired from any session executing the triggering
DML statements. Can be fired only from the form that define the trigger. e)
Can cause other database triggers to fire.Can cause other database triggers
to fire,but not other form triggers.
|
|
24. What is an
UTL_FILE.What are different procedures and functions associated
|
|
with it. UTL_FILE is a
package that adds the ability to read and write to operating system files
Procedures associated with it are FCLOSE, FCLOSE_ALL and 5 procedures to
output data to a file PUT, PUT_LINE, NEW_LINE, PUTF, FFLUSH.PUT,
FFLUSH.PUT_LINE,FFLUSH.NEW_LINE. Functions associated with it are FOPEN,
ISOPEN.
|
|
25. Can you use a
commit statement within a database trigger.
|
|
No
|
|
26. What is the
maximum buffer size that can be specified using the DBMS_OUTPUT.ENABLE
function?
|
|
1,000,000
|
|
Oracle Interview
Questions
|
|
1. When looking at the
estat events report you see that you are getting busy buffer waits. Is this
bad? How can you find what is causing it
|
|
Buffer busy waits
could indicate contention in redo, rollback or data blocks. You need to check
the v$waitstat view to see what areas are causing the problem. The value of
the "count" column tells where the problem is, the
"class" column tells you with what. UNDO is rollback segments, DATA
is data base buffers.
|
|
2. If you see
contention for library caches how can you fix it
|
|
Increase the size of
the shared pool.
|
|
3. If you see
statistics that deal with "undo" what are they really talking about
|
|
Rollback segments and
associated structures.
|
|
4. If a tablespace has
a default pctincrease of zero what will this cause (in relationship to the
smon process)
|
|
The SMON process won?t
automatically coalesce its free space fragments.
|
|
5. If a tablespace
shows excessive fragmentation what are some methods to defragment the
tablespace? (7.1,7.2 and 7.3 only)
|
|
In Oracle 7.0 to 7.2
The use of the 'alter session set events 'immediate trace name coalesce level
ts#';? command is the easiest way to defragment contiguous free space
fragmentation. The ts# parameter corresponds to the ts# value found in the
ts$ SYS table. In version 7.3 the ?alter tablespace coalesce;? is best.
If the free space isn?t contiguous then export, drop and import of the
tablespace contents may be the only way to reclaim non-contiguous free space.
|
|
6. How can you tell if
a tablespace has excessive fragmentation
|
|
If a select against
the dba_free_space table shows that the count of a tablespaces extents is
greater than the count of its data files, then it is fragmented.
|
|
7. You see the
following on a status report: redo log space requests 23 redo log space wait
time 0 Is this something to worry about? What if redo log space wait time is
high? How can you fix this Since the wait time is zero, no. If the wait time
was high it might indicate a need for more or larger redo logs.
|
|
8. What can cause a
high value for recursive calls? How can this be fixed
|
|
A high value for
recursive calls is cause by improper cursor usage, excessive dynamic space
management actions, and or excessive statement re-parses. You need to
determine the cause and correct it By either relinking applications to hold
cursors, use proper space management techniques (proper storage and sizing)
or ensure repeat queries are placed in packages for proper reuse.
|
|
9. If you see a pin
hit ratio of less than 0.8 in the estat library cache report is this a
problem? If so, how do you fix it
|
|
This indicate that the
shared pool may be too small. Increase the shared pool size.
|
|
10. If you see the
value for reloads is high in the estat library cache report is this a matter
for concern
|
|
Yes, you should strive
for zero reloads if possible. If you see excessive reloads then increase the
size of the shared pool.
|
|
11. You look at the
dba_rollback_segs view and see that there is a large number of shrinks and
they are of relatively small size, is this a problem? How can it be fixed if
it is a problem
|
|
A large number of
small shrinks indicates a need to increase the size of the rollback segment
extents. Ideally you should have no shrinks or a small number of large
shrinks. To fix this just increase the size of the extents and adjust optimal
accordingly.
|
|
12. You look at the
dba_rollback_segs view and see that you have a large number of wraps is this
a problem
|
|
A large number of
wraps indicates that your extent size for your rollback segments are probably
too small. Increase the size of your extents to reduce the number of wraps.
You can look at the average transaction size in the same view to get the
information on transaction size.
|
|
Oracle Interview
Questions
|
|
1. You have just
started a new instance with a large SGA on a busy existing server.
Performance is terrible, what should you check for
|
|
The first thing to check
with a large SGA is that it isn?t being swapped out.
|
|
2. What OS user should
be used for the first part of an Oracle installation (on UNIX)
|
|
You must use root
first.
|
|
3. When should the
default values for Oracle initialization parameters be used as is
|
|
Never
|
|
4. How many control
files should you have? Where should they be located
|
|
At least 2 on separate
disk spindles. Be sure they say on separate disks, not just file systems.
|
|
5. How many redo logs
should you have and how should they be configured for maximum recoverability
|
|
You should have at
least three groups of two redo logs with the two logs each on a separate disk
spindle (mirrored by Oracle). The redo logs should not be on raw devices on
UNIX if it can be avoided.
|
|
6. You have a simple application
with no "hot" tables (i.e. uniform IO and access requirements). How
many disks should you have assuming standard layout for SYSTEM, USER, TEMP
and ROLLBACK tablespaces
|
|
At least 7, see disk
configuration answer above.
|
|
7. Describe third
normal form
|
|
Something like: In
third normal form all attributes in an entity are related to the primary key
and only to the primary key
|
|
8. Is the following
statement true or false:
|
|
"All relational
databases must be in third normal form" False. While 3NF is good for
logical design most databases, if they have more than just a few tables, will
not perform well using full 3NF. Usually some entities will be denormalized
in the logical to physical transfer process.
|
|
9. What is an ERD
|
|
An ERD is an
Entity-Relationship-Diagram. It is used to show the entities and
relationships for a database logical model.
|
|
10. Why are recursive
relationships bad? How do you resolve them
|
|
A recursive
relationship (one where a table relates to itself) is bad when it is a hard
relationship (i.e. neither side is a "may" both are
"must") as this can result in it not being possible to put in a top
or perhaps a bottom of the table (for example in the EMPLOYEE table you
couldn?t put in the PRESIDENT of the company because he has no boss, or the
junior janitor because he has no subordinates). These type of relationships
are usually resolved by adding a small intersection entity.
|
|
11. What does a hard
one-to-one relationship mean (one where the relationship on both ends is
"must")
|
|
Expected answer: This
means the two entities should probably be made into one entity.
|
|
12. How should a
many-to-many relationship be handled
|
|
By adding an
intersection entity table
|
|
13. What is an
artificial (derived) primary key? When should an artificial (or derived)
primary key be used
|
|
A derived key comes
from a sequence. Usually it is used when a concatenated key becomes too
cumbersome to use as a foreign key.
|
|
Oracle Interview
Questions
|
|
1. When should you
consider denormalization
|
|
Whenever performance
analysis indicates it would be beneficial to do so without compromising data
integrity.
|
|
2. How can you
determine if an Oracle instance is up from the operating system level
|
|
There are several base
Oracle processes that will be running on multi-user operating systems, these
will be smon, pmon, dbwr and lgwr. Any answer that has them using their
operating system process showing feature to check for these is acceptable.
For example, on UNIX a ps -ef|grep dbwr will show what instances are up.
|
|
3. Users from the PC
clients are getting messages indicating : ORA-06114: (Cnct err, can't
get err txt. See Servr Msgs & Codes Manual)
|
|
What could the problem
be The instance name is probably incorrect in their connection string.
|
|
4. Users from the PC
clients are getting the following error stack: ERROR: ORA-01034: ORACLE not
available ORA-07318: smsget: open error when opening sgadef.dbf file. HP-UX
Error: 2: No such file or directory
|
|
What is the probable
cause The Oracle instance is shutdown that they are trying to access, restart
the instance.
|
|
5. How can you
determine if the SQLNET process is running for SQLNET V1? How about V2
|
|
For SQLNET V1 check
for the existence of the orasrv process. You can use the command "tcpctl
status" to get a full status of the V1 TCPIP server, other protocols
have similar command formats. For SQLNET V2 check for the presence of the
LISTENER process(s) or you can issue the command "lsnrctl status".
|
|
6. What file will give
you Oracle instance status information? Where is it located
|
|
The alert.ora log. It
is located in the directory specified by the background_dump_dest parameter
in the v$parameter table.
|
|
7. Users aren?t being
allowed on the system. The following message is received: ORA-00257 archiver
is stuck. Connect internal only, until freed What is the problem The archive
destination is probably full, backup the archive logs and remove them and the
archiver will re-start.
|
|
8. Where would you
look to find out if a redo log was corrupted assuming you are using Oracle
mirrored redo logs
|
|
There is no message
that comes to the SQLDBA or SRVMGR programs during startup in this situation,
you must check the alert.log file for this information.
|
|
9. You attempt to add
a datafile and get: ORA-01118: cannot add anymore datafiles: limit of 40
exceeded What is the problem and how can you fix it When the database was
created the db_files parameter in the initialization file was set to 40. You
can shutdown and reset this to a higher value, up to the value of
MAX_DATAFILES as specified at database creation. If the MAX_DATAFILES is set
to low, you will have to rebuild the control file to increase it before
proceeding.
|
|
10. You look at your
fragmentation report and see that smon hasn?t coalesced any of you
tablespaces, even though you know several have large chunks of contiguous
free extents. What is the problem
|
|
Check the
dba_tablespaces view for the value of pct_increase for the tablespaces. If
pct_increase is zero, smon will not coalesce their free space.
|
|
11. Your users get the
following error: ORA-00055 maximum number of DML locks exceeded What is the
problem and how do you fix it The number of DML Locks is set by the
initialization parameter DML_LOCKS. If this value is set to low (which it is
by default) you will get this error. Increase the value of DML_LOCKS. If you
are sure that this is just a temporary problem, you can have them wait and
then try again later and the error should clear.
|
|
12. You get a call
from you backup DBA while you are on vacation. He has corrupted all of the
control files while playing with the ALTER DATABASE BACKUP CONTROLFILE
command. What do you do
|
|
As long as all
datafiles are safe and he was successful with the BACKUP controlfile command
you can do the following: CONNECT INTERNAL STARTUP MOUNT (Take any read-only
tablespaces offline before next step ALTER DATABASE DATAFILE .... OFFLINE;)
RECOVER DATABASE USING BACKUP CONTROLFILE ALTER DATABASE OPEN RESETLOGS;
(bring read-only tablespaces back online) Shutdown and backup the system,
then restart If they have a recent output file from the ALTER DATABASE BACKUP
CONTROL FILE TO TRACE; command, they can use that to recover as well. If no
backup of the control file is available then the following will be required:
CONNECT INTERNAL STARTUP NOMOUNT CREATE CONTROL FILE .....; However, they
will need to know all of the datafiles, logfiles, and settings for
MAXLOGFILES, MAXLOGMEMBERS, MAXLOGHISTORY, MAXDATAFILES for the database to
use the command.
|
|
Oracle Interview
Questions
|
|
1. How would you
determine the time zone under which a database was operating? 2. Explain the
use of setting GLOBAL_NAMES equal to TRUE. 3. What command would you use to
encrypt a PL/SQL application? 4. Explain the difference between a FUNCTION,
PROCEDURE and PACKAGE. 5. Explain the use of table functions. 6. Name three
advisory statistics you can collect. 7. Where in the Oracle directory tree
structure are audit traces placed? 8. Explain materialized views and how they
are used. 9. When a user process fails, what background process cleans up
after it? 10. What background process refreshes materialized views? 11. How
would you determine what sessions are connected and what resources they are
waiting for? 12. Describe what redo logs are. 13. How would you force a log
switch? 14. Give two methods you could use to determine what DDL changes have
been made. 15. What does coalescing a tablespace do? 16. What is the
difference between a TEMPORARY tablespace and a PERMANENT tablespace? 17.
Name a tablespace automatically created when you create a database. 18. When
creating a user, what permissions must you grant to allow them to connect to
the database? 19. How do you add a data file to a tablespace? 20. How do you
resize a data file? 21. What view would you use to look at the size of a data
file? 22. What view would you use to determine free space in a tablespace?
23. How would you determine who has added a row to a table? 24. How can you
rebuild an index? 25. Explain what partitioning is and what its benefit is.
26. You have just compiled a PL/SQL package but got errors, how would you
view the errors? 27. How can you gather statistics on a table? 28. How can
you enable a trace for a session? 29. What is the difference between the
SQL*Loader and IMPORT utilities? 30. Name two files used for network connection
to a database.
|
|
Oracle Interview
Questions
|
|
1. In a system with an
average of 40 concurrent users you get the following from a query on rollback
extents:
|
|
ROLLBACK CUR EXTENTS
|
|
--------------------------
|
|
R01 11
|
|
R02 8
|
|
R03 12
|
|
R04 9
|
|
SYSTEM 4
|
|
You have room for each
to grow by 20 more extents each. Is there a problem? Should you take any
action
|
|
No there is not a
problem. You have 40 extents showing and an average of 40 concurrent users.
Since there is plenty of room to grow no action is needed.
|
|
2. You see multiple
extents in the temporary tablespace. Is this a problem
|
|
As long as they are
all the same size this isn?t a problem. In fact, it can even improve
performance since Oracle won?t have to create a new extent when a user needs
one.
|
|
3. Define OFA.
|
|
OFA stands for Optimal
Flexible Architecture. It is a method of placing directories and files in an
Oracle system so that you get the maximum flexibility for future tuning and
file placement.
|
|
4. How do you set up
your tablespace on installation
|
|
The answer here should
show an understanding of separation of redo and rollback, data and indexes
and isolation os SYSTEM tables from other tables. An example would be to
specify that at least 7 disks should be used for an Oracle installation so
that you can place
|
|
SYSTEM tablespace on
one
|
|
Redo logs on two
(mirrored redo logs)
|
|
TEMPORARY tablespace
on another,
|
|
ROLLBACK tablespace on
another and
|
|
still have two for
DATA and INDEXES.
|
|
They should indicate
how they will handle archive logs and exports as well. As long as they have a
logical plan for combining or further separation more or less disks can be
specified.
|
|
5. What should be done
prior to installing Oracle (for the OS and the disks)
|
|
adjust kernel
parameters or OS tuning parameters in accordance with installation guide. Be
sure enough contiguous disk space is available.
|
|
6. You have installed
Oracle and you are now setting up the actual instance. You have been waiting
an hour for the initialization script to finish, what should you check first
to determine if there is a problem
|
|
Check to make sure
that the archiver isn?t stuck. If archive logging is turned on during install
a large number of logs will be created. This can fill up your archive log
destination causing Oracle to stop to wait for more space.
|
|
7. When configuring
SQLNET on the server what files must be set up
|
|
INITIALIZATION file,
TNSNAMES.ORA file, SQLNET.ORA file
|
|
8. When configuring
SQLNET on the client what files need to be set up
|
|
SQLNET.ORA,
TNSNAMES.ORA
|
|
9. What must be
installed with ODBC on the client in order for it to work with Oracle
|
|
SQLNET and PROTOCOL
(for example: TCPIP adapter) layers of the transport programs.
|
|
General Oracle
Questions
|
|
What Oracle products
have you worked with?
|
|
What version of Oracle
were you running?
|
|
Compare Oracle to any
other database that you know. Why would you prefer to work on one and not on
the other?
|
|
Oracle DBA Questions
|
|
2. Did you use online
or off-line backups? Why?
|
|
used both based on
business needs.
|
|
3. If you have to
advise a backup strategy for a new application, how would you approach it and
what questions will you ask?
|
|
is down time allowed,
and what is this being used for Prod,QA or Dev. how huge this Db gonna be in
few months .. what type of data is being used in this DB etc..
|
|
4. If a customer calls
you about a hanging database session, what will you do to resolve it?
|
|
first thing ...any
errors , if not check for session status.. locks waits , disk io, explain
plan .. etc
|
|
5. How many control
files and redo logs should a database have? atleast
|
|
2 ctl's and 3 logs
|
