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-
ASM
- Creating ASM Instance and diskgroups manually without DBCA
- 20 ASM Realtime | Interview Questions
- How to make a cold backup for database running on ASM ( using RMAN )
- Moving a Single Datafile from File System to ASM System (METHOD 1)
- Moving a Single Datafile from File System to ASM System (METHOD 2)
- Things to consider while adding new disk/ Rebalancing existing Disk Group
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Dataguard
- Dataguard Modes
- Dataguard Modes - II
- Oracle DataGuard Setup
- invalid archived log deletion policy
- recover from the Loss of a Datafile on a Standby Database ?
- MRP terminated with ORA-00600: internal error code, arguments
- Recover archive gaps in standby database - using 2 methodss
- Gap Resolution in Dataguard
- Convert Physical Standby to Snapshot Standby and Vice Versa
- Re-create Redo-logs on Standby/ Primary
- Pre-check for DataGuard switchover Process
- ORA-19815: WARNING: db_recovery_file_dest_size
- How do you purge old archivelogs which are applied on Standby DB
- Pre-check For SWITCHOVER using DG Broker
- https://oracle-dba-help.blogspot.com/2016/03/data-guard-modes.html
- ORA-01274 : RENAME THE UNKNOW FILE IN THE STANDBY DATABASE
- Database Creation in Easy 6 Steps
- Oracle Networking
- Tablespace management
- Housekeep : Quick Tips for DBA
- Health check for DB
- ORA-12537 While Connecting To Database Via Listener
- How to identify the applied patche-set of your Oracle Home
- Accessing a schema without knowing the password
- ORA-12505: TNS:listener does not currently know of SID given in connect descriptor
- Session Related Scripts
- How to check ORA Error on DB Server – Beginner Tip
- Working with Redo Logs
- Decommission of Oracle Database
- Roles in Oracle - Managing Users
- Oracle Release Number Format
- Troubleshooting Handy-Guide
- Understanding the Upgradation Process
- Query to find the session creating more redo
- Audit in Oracle
- Troubleshooting Internal Errors and Error-Look-up Tool on MOS
- Troubleshooting Issues with Undo Tablespace
- User Management
- User Management - II
- Data Pump Gets Better
- MEMORY_TARGET Parameter
- Installing PostgreSQL Server on CentOS, RHEL 6 / 7 Systems
- Creating a database in Postgres
- Initialize multiple Postgres instance on the same RHEL server
- How to stop starting of clusters while starting up services
- Setup a streaming replication
- Switchover- master server and warm standby (with streaming replication)
- All About Physical Replication and Log shipping
- PostgreSQL Upgrade and troubleshooting
- Timeline Switch issue
- Query to identify the lag in replication
- Drop table : ERROR: must be owner of relation table_name
- PgBadger
- PgCenter
- PgTune
- Internals of Toast Table
- Influencing Query Execution Plan
- Create Extension ERROR
- Find Uptime in PostgreSQL
- Set DB Timezone
- Clear RAM Cache, Buffer
- Read-Only User in Postgres
- Everything you need to know about Streaming Replication
- Ora2Pg Migrate Oracle to Postgres
- Total Page Cost
- PostgreSQL 13 - Everything you need to know
- Startup Failure - .conf file
- All About Postgres Upgrade
- Basic Guide
- Session Related Scripts
- AWR :: Beginners Guide
- All About ASH - Active Session History
- Wait Events : checkpoint busy waits or archiver busy waits
- Find sessions performing sort operations : TEMP Tablespace occupants
- Generate ADDM task and generate its report for Tuning
- Database Performance Tuning Scripts -Keep Handy
- Buffer Busy Wait
- Simulating the Deadlock
- Latches
- Steps to Schedule any RMAN Jobs In Windows Server
- ORA-01194: file 1 needs more recovery to be consistent
- Loss of Current Online Redo-Log
- RMAN "baby Steps"
- Recovery of ControlFiles
- Loss of Datafile
- Recovery from complete loss of all online redo log files
- Block Change Tracking
- RMAN Questions
- Instance Recovery
- Redundancy and Recovery window in RMAN
- Cold Backup
- Database Cloning
- Contact
- Drop Database using RMAN
- PITR to older Incarnation
Wednesday 7 September 2016
Monday 5 September 2016
How to Crack DBA Interviews
FREE Sign-Up with Gmail and Receive Pdf's and Updates via Mail -Click Here
People
always think that Preparing for Oracle Certification and being an Oracle
Certified can get you a Job. But the real thing is you will knowledge by
Hands-on Experience.
First thing, understand
the real issues one would encounter while ACTUALLY doing the work. For example,
upgrading from Oracle 10g to 11g. Pre-checks for Patching OR pre-requisites for
a Switchover in Data-guard, like these.
People don’t
care much how many certifications you have. They want to know that you’ve had
enough hands on.
Second thing is 80% of
the DBA interviews are performance tuning questions. So at least, be well
prepared of each and every issues a DBA can face in his entire job.
So instead
of spending many days & a lot of money on Oracle certifications, set up
your own Virtual Box and start practicing on the following topics.
You must focus on the few Oracle topics that are really important
for the job.
Important Topic for Oracle Interviews
Obviously
you should know about Oracle Architecture.
That forms the basis for everything else..
·
Dataguard
·
RMAN Backups
·
Oracle Golden Gate
·
Real Application Clusters (RAC)
·
Performance Tuning / SQL Tuning
That's all
folks, just leave a simple comment below about single, the most challenging
thing you face in learning or for becoming an Oracle DBA.
If you
really like this post and thought this is useful so please “Follow us” and be a
part of our blog and help us grow.
See Also :
How to Become a Good DBA
How to prepare for DBA Interview
General Tips for a DBA Interview - Final Preperation
11g New Features
This is the most frequently asked interview Question in DBA Interviews that What are the 11g New Features ?
Below are the 11g New Features :
·
Automatic Memory Tuning
-Automatic PGA tuning was introduced
in Oracle 9i.
-Automatic SGA tuning was introduced
in Oracle 10g.
-In 11g, all memory can be tuned
automatically by setting one parameter. You literally tell Oracle how much
memory it has and it determines how much to use for PGA, SGA and OS Processes.
Maximum and minimum thresholds can be set.
·
Database Capture/replay database workloads
Allows the total database workload to be
captured, transferred to a test database created from a backup or standby
database then replayed to test the affects of an upgrade or system change.
·
Index can be rebuild ‘online’
Online index build with NO pause to DML.
·
RMAN By-Pass
UNDO
Rman backup
can bypass undo. Undo tablespaces are getting huge, but contain lots of useless
information. So, RMAN can bypass those types of tablespace. Beneficial for
exporting a tablespace from backup.:-
Source: Laurent
·
Tables can be made read only table :-
E.g ;
SQL> alter
table <table_name> read only
SQL> alter table <table_name> read write
·
Case sensitive password
Init.ora
parameter
sec_case_sensitive_logon
= (TRUE FALSE)
To Find
users who have case sensitive or case insensitive passwords, Use below queries
SQL>
SELECT USERNAME,PASSWORD_VERSIONS FROM DBA_USERS
Implementation
in Password file
$ orapwd
file=orclpwd password=manager ignorecase=y
·
Passwords are expected to also become case sensitive
In addition to limiting the number
of failed login attempts to 10 (the default configuration in 10gR2), Oracle 11g
beta’s planned default settings provide a feature to expire passwords every 180
days, and limit to seven the number of times a user can login with an expired
password before disabling access.
·
ADR ( Automatic Diagnostic Repository)
Oracle 11g introduce new
tool/utility called ADRCI known as ADR command line tool. This tool allow user
to interact with ADR , check alert log, check health monitor(HM) status. It is
just a file based repository of diagnostic data. ADR gives lot flexibility to
maintain / handle diagnostic data.
When critical errors(i.e Problem)
are detected, they automatically create an “incident” ( one occurrence of
problem is Incident i.e relation between problem and incident is one to many).
Information(trace ,dump ) related to
the incident is automatically captured in file based repository known as ADR (
Automatic Diagnostic repository), all the incident related files are tagged
with Incident Number and certain health checks are run automatically. This
information can be packaged to be sent to Oracle support
$ adrci
adrci> show alert ( it will open alert in vi editor )
adrci> show alert -tail ( Similar to Unix tail command )
adrci> show alert -tail 200 ( Similar to Unix Command tail
-200 )
adrci> show alert -tail -f ( Similar to Unix command tail -f
)
RMAN New Features (11g)
·
Active Database Duplication
We can create a duplicate or standby
database over the network without taking backup or using old backup.
·
Configuring backup compression (Compression Algorithm)
In 11g can use CONFIGURE command to choose between
the BZIP2 and ZLIB compression algorithms for RMAN backups.
·
Block Change Tracking (BCT)
Faster incremental backups on Physical Standby DB’s :
In 11g we can enable block change
tracking on a physical standby database (ALTER DATABASE ENABLE/DISABLE BLOCK
CHANGE TRACKING).This new 11g feature
enables faster Incremental backups on a physical standby database than in
previous releases. Because RMAN identify
the changed blocks since the last incremental backup.
·
Parallel backup and restore for Huge size files
RMAN Backups of large sized data
files now use multiple parallel server processes to efficiently
distribute the workload for each file.
This features improves the
performance of backups.
Data Guard Enhancements , "Active Data Guard"
1)
Data Protection
* Advanced Compression
* Lost-write protection
* Fast-Start Failover
2)
Increase ROI
* Active Data Guard
* Snapshot Standby
3)
High Availability
* Faster Redo Apply
* Faster failover & switchover
* Automatic Failover using ASYNC
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