Why do we need to
maintain our data in database?
As we all
know database has a availability of a storage system, the most
obvious of these being persistence.
we can identify the
following reasons for wanting a Database Management Systems short
for DBMS:
We need to share data
of all kinds between users (except for very small systems), between tools
working on them, and usually between different computers. All should be able to
work with the same set of data.
We need persistent storage
and storage must be reliable.
Several users and/or
several tools must be able to safely access the same data concurrently.
A DBMS may provide more
efficient access to large amounts of data, through indexing and other
optimizations.
A DBMS and its data model
provides an abstraction; we do not need to care about the physical storage
format.
A DBMS may also
be used for communication between different users or applications.
What are the responsibilities
of a Database Administrator?
Installing and upgrading
the Oracle Server and application tools.
Allocating system storage
and planning future storage requirements for the database system.
Managing primary database
structures (tablespaces) .
Managing primary objects
(table, views, indexes)
Enrolling users and
maintaining system security.
Ensuring compliance with
Oralce license agreement Controlling and monitoring user access to the database.
Monitoring and optimizing
the performance of the database.
Planning for backup and
recovery of database information.
Maintain archived data on
tape Backing up and restoring the database.
Contacting Oracle
Corporation for technical support.
What are the Daily
Activities of a Oracle DBA ?
1. Check the Database
availability
2. Check the Listener
availability
3. Check the alert log file
for errors
4. Monitoring space
availability in table spaces
5. Monitoring mount point
6. Validate Database backup
or Archive backup
7. Find objects which is going
to reach max extents
8. Database Health check
9. CPU, Processor, Memory
usage
What is the most
challenging aspect of your job?
This question will give you clues about the mindset of the DBA. When asked what is challenging about the DBA job, the DBA’s answer will reveal a great deal about his or her personality and ability to work well with other people. The DBA who talks about the technical challenges of the job and difficulties administering and maintaining the database may not be ideally suited for a position where contact for the development staff is critical. On the other hand, the DBA who speaks openly of the challenges associated with getting the developers fast answers and accurate information might be a better consideration.
This question will give you clues about the mindset of the DBA. When asked what is challenging about the DBA job, the DBA’s answer will reveal a great deal about his or her personality and ability to work well with other people. The DBA who talks about the technical challenges of the job and difficulties administering and maintaining the database may not be ideally suited for a position where contact for the development staff is critical. On the other hand, the DBA who speaks openly of the challenges associated with getting the developers fast answers and accurate information might be a better consideration.
How do you perceive
the relationship between the DBA and the development staff?
DBAs by virtue of their high pay and product-specific knowledge, tend to think of developers as underlings, in some cases, DBAs view developers with outright contempt, believing their queries to be naive. On the other hand, DBAs with the proper attitude will respond to this question by talking about the developers as clients to whom they provide data services essential to the application. In some shops, the DBAs may be responsible for code, reviewing SQL queries, or DML statements written by developers; so, a good relationship is vital.
DBAs by virtue of their high pay and product-specific knowledge, tend to think of developers as underlings, in some cases, DBAs view developers with outright contempt, believing their queries to be naive. On the other hand, DBAs with the proper attitude will respond to this question by talking about the developers as clients to whom they provide data services essential to the application. In some shops, the DBAs may be responsible for code, reviewing SQL queries, or DML statements written by developers; so, a good relationship is vital.
What is a database instance?
A database instance
(Server) is a set of memory structure and background processes that
access a set of database files. The process can be shared by all users. The
memory structure that are used to store most queried data from database. This
helps up to improve database performance by decreasing the amount of I/O
performed against data file.
What are mandatory
background processes in Oracle Database?
Smon, pmon, ckpt, dbwr, lgwr
What is OLTP database?
OLTP means Online
Transaction Processing. OLAP means Online Analytical Processing. OLTP deals
with processing of data from transactional systems. For example, an application
that loads the reservation data of a hotel is an OLTP system. An OLTP system is
designed mainly keeping in the mind the performance of the end application. It
comprises of the application, database & the reporting system that directly
works on this database. The database in an OLTP system would be designed in a
manner as to facilitate the improvement in the application efficiency thereby
reducing the processing time of the application.
What is
OLAP database?
OLAP systems were mainly
developed using data in a warehouse. Having said that a need was felt to
isolate older data, it was necessary to store them in a format that would be
useful in easing out the reporting bottlenecks. A need was felt to isolate the
data & redesign the application data to such a format & structure that
this data repository would be the prime source of business decisions. Coming
back to OLAP systems, these systems were mainly developed on the isolated data.
What is the basic
element of Base configuration of an oracle Database?
It consists of one or more data files. One or more control files.
Two or more redo
log groups. The Database contains multiple users/schemas one or more
rollback segments, one or more tablespaces Data dictionary tables User objects
(table, indexes, views etc.,) The server that access the database consists of
SGA (Database buffer cache, Shared pool , Redo log buffer)
SMON (System monitor)
PMON (Process MONitor)
LGWR (LoG Write)
DBWR (Data Base Write)
ARCH (ARCHiver)
CKPT (Check Point)
RECO
Dispatcher
User Process with associated PGA.
PMON (Process MONitor)
LGWR (LoG Write)
DBWR (Data Base Write)
ARCH (ARCHiver)
CKPT (Check Point)
RECO
Dispatcher
User Process with associated PGA.
What is the function
of Optimizer?
The goal of the optimizer
is to choose the most efficient way to execute a SQL statement.(Chooses best
excution plan based on time and cost.
What is Execution
Plan?
The combination of the
steps the optimizer chooses to execute a statement is called an execution plan.
What are the different
approaches used by Optimizer in choosing an execution plan?
Rule-based and Cost-based.
Rule-based and Cost-based.
What are the
different Components of SGA?
1. The fixed SGA (Fixed
SGA)
2. Default block buffer (Db cache)
3. Different Standard Block buffers
4. Redo log buffer (Redo log buffer)
5. Java pool (Java pool)
6. Large pool (Large pool)
7. Shared pool (Shared pool)
8. Stream pool (Stream pool)
9. Result cache
2. Default block buffer (Db cache)
3. Different Standard Block buffers
4. Redo log buffer (Redo log buffer)
5. Java pool (Java pool)
6. Large pool (Large pool)
7. Shared pool (Shared pool)
8. Stream pool (Stream pool)
9. Result cache
What is
dictionary cache?
The dictionary
cache stores “metadata” (data about your tables and indexes) and it’s also
known as the row cache. It is used to cache data dictionary related information
in RAM for quick access. The dictionary cache is like the buffer cache, except
it’s for Oracle data dictionary information instead of user
information.
What is
Database Buffers?
Database buffers are cache in the SGA used to hold the data blocks that
are read from the data segments in the database such as
tables, indexes and clusters DB_BLOCK_BUFFERS parameter in INIT.ORA decides the
size
What is the
functionality of SYSTEM table space?
System
tablespace is a main part of oracle database. All the database information
is in it. it is created when database is created. It is managed by
oracle server . Dba cannot change its contents. it contains the data
dictionary objects .
What is
the function of checkpoint (CKPT)?
Checkpoint is
a background process which ensures dbwr process has written data to datafiles
and upadates control file and datafile header to establish data consistency.
The CKPT is also useful to get the point in time from where to begin the
recovery in case of failure.
When does LGWR
write to the database?
Log Writer
(LGWR) writes redo log entries. it is generated in the redo log buffer of the
SGA to on-line Redo Log
File.LGWR writes redo log entries into an on-line redo log file when
transactions commit and the log buffer files are full.
What is Shared
SQL Area ?
A shared SQL
area contains the parse tree and execution plan for a given SQL
statement. Oracle saves memory by using one shared SQL area for SQL
statements run multiple times, which often happens when many users run the same
application. Oracle allocates memory from the shared pool when a new SQL
statement is parsed, to store in the shared SQL area. The size of this memory
depends on the complexity of the statement. If the entire shared pool has
already been allocated, Oracle can deallocate items from the pool using a
modified LRU (least recently used) algorithm until there is enough free space
for the new statement's shared SQL area.
What
Does DBWR do?
Database
writer writes modified blocks from the database buffer cache to the data files.
What is server processes?
A server process is one
that handles user requests. When you type in a SQL statement, the server
process handles the parsing and running of that SQL statement,
Name the process which
carries the request to the memory components and also fetches from disk to
buffer?
Server Process
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nice bro
ReplyVery nice piece of information thank you for sharing. Know more about Oracle DBA Training In Bangalore
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