See Also : DBA Interview for 2+
Q. What is
the difference between process and thread.
Creation of
new process requires new resources and Address space whereas the thread can be
created
in the same
address space of the process which not only saves space and resources but are
also easy to
create and
delete, and many threads can exists in a process.
Q. What is
main purpose of CHECKPOINT?
A Checkpoint
is a database event, which synchronizes the data blocks in memory with the
datafiles on disk.
A checkpoint
has 2 purposes:
-1. to
establish data consistency
-2. Enable
faster database recovery.
Q. What is
PGA ?
PGA -
Program Global Area
or the
Process Global Area is a memory region that contains
data and
control information for a single
server
process or a single background process.
The PGA is
allocated when a process is created and de-allocated when the process is
terminated.
PGA is an
area that is used by only one process.
Q. Different
type of Database Failures
Statement
failure failed SQL is automatically rolled back and an error is returned to
user.
User Process
failure abnormal disconnect PMON detects and rollsback and releases locks.
User Error
(drop table, data) DBA is required to recover data (import or incomplete
recovery)
Media
Failure Loss or corruption of files DBA needs to apply appropriate recovery.
Instance
Failure Abnormal shutdown Instance simply needs restarted, SMON auto
recovers by:
-Rolling forward changes in the redo log not
recorded in the data files before Open of database.
-Rollbacks can occur after the database is
open, when block data is requested.
Q. 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
Q.What is
the use of the RESUMABLE parameter in EXPORT?
The
RESUMABLE parameter allows the export to
1. Suspend
if a space allocation issue occurs
2. Wait
until the space allocation issue is solved
3. Then
resume and therefore not to abort, provided a timeout is set appropriately.
Q. Name
three advisory statistics you can collect.
Buffer Cache
Advice, Segment Level Statistics, & Timed Statistics.
Q. 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 support systems.
Tell me the
two methods you could use to determine what DDL changes have been made.
Logminer or
Streams
Q. Locally
Managed TEMP Tablespace is 100% FULL and there is no space available to
add datafile
to increase TEMP tablespace. What can you do that might free up TEMP space?
A.) You can
try one of the following to free up TEMP space
1. Issue ALTER
TABLESPACE PCTINCREASE 1 followed by
ALTER
TABLESPACE PCTINCREASE 0 command;
2. Close
some of the idle sessions connected to the database
Interviewer
may ask you - - ‘’Do you have something to Ask...?’’
Following
are the Questions a DBA can Ask to the Interviewer
1. What
processes do you follow while implementing changes in production?
2. Beside the
DBAs and system administrators, who has access to the "Oracle"
operating
system account?
3. How often is
the oracle operating system account password changed?
4. Are the DBAs
co-located with the teams they support? How is capacity planning performed?
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