Oracle Data Guard Interview Questions
Oracle Data Guard Frequently Asked Questions (FAQ).
Question
What is meant by real time apply in DataGuard environment?
If the transactions from Primary to secondary are applied by using the redo logs, then it is called real time apply.
Question
How to verify the real time apply enabled or not on standby?
SQL>select RECOVERY_MODE from v$archive_dest_status;
o/p ==> Managed Real Time Apply
For normal set up : o/p ==> Managed
Question
How to verify redo apply in standby database?
Answer:
| SQL>Select process,Status ,thread#,sequence#, block#, blocks from v$managed_standby; |
Question
How to stop redo apply in standby database?
Answer:
| SQL>alter database recover managed standby database cancel; |
Question
How to maintain 1 hour gap between primary database and standby/secondary database?
Answer
| SQL> Alter database recover managed standby database delay 60 disconnect from session; |
Question
what is the reason for not able to run the below command ?
Command: alter pluggable database <dbname> save state;
Answer:
Database is in read only mode;
Question
What is the output of the command “select open_mode from v$database;” ?
Answer:
READ ONLY WITH APPLY
Question
What command do you use to know the protection mode of the data Guard by using DG broker?
Answer
show configuration
Question
show database <dbname> wont work in the above scenario?
Answer:
yes, it will not work.
Question
What is the pre-requisite to establish a logical replication (logical standby) ?
Answer:
Unique key should be there in the table @primary database.
Question
Which command do you run on primary to create metadata for log miner to apply SQLs on logical standby?
Answer:
execute dbms_logstdby
Question
Which function is used to cancel DML apply on a certain table in Logical standby?
Answer
DBMS_LOGSTDBY.SKIP
Question
What command is used to stop the replication in logical standby DB?
Answer
alter database stop logical standby apply;
Question
What is the command to prepare the logical standby Database ?
Answer
alter database prepare to switchover to logical standby?
Question
Where do you run the above command ? is it on primary or Standby?
Answer
on Primary.
Question
What is the command to switchover so the logical standby becomes the new primary?
Answer
SQL>alter database commit to switchover to primary;
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