STANDBY DATABASE

[adda.road@yahoo.com]

Hi ALL,

Can we perform DMLs on STANDby DATABASE?

what is difference between CLONE DATABASE and standby database?

If possible please anybody post the links for FAQ on Oracle RAC and STANDBY databases (DATA Gaurd).

I am preparing for Interview.

Thanks every one in advance.

Thanks,
Rampa.

[Tim...]

Hi.

You cannot perform regular DML on a standby because it is in managed recover, rather than in read-write mode.

A clone is an exact copy of a database, but once the clone is complete it is in no way linked to the original database, so they can both be altered with no affect on each other.

No idea about FAQs. You can check out articles on my sight on these subjects.

Cheers

Tim...

[adda.road@yahoo.com]

Hi Tim,

Thank You so much for reply.

Could you please explain more about managed recover mode?

Are dmls are not permited even on logical standby database?

Thanks,
Rampa.

[Tim...]

Hi.

Managed recovery is just the state of the standby in a physical standby. Essentially, it is permanently in recovery mode, like you would do manually when recovering a database from a backup using the archived logs. When an archived redo log arrives it is recovered straight away because the database is permanently in a state of recovery, hence managed recovery. This is why the database is not open and not available for use. In 11g active data guard was introduced that allows the standby to be open read-only while still in managed recovery. This costs extra because the standby can now be used for reporting and still be kept up to date.

DML is permitted on logical standby. It is different because the database is open for read-write and can be used. It can even diverge from the primary server. I'm not a fan of logical standby. There are also licensing issues around it because you have a fully functional database as the standby, rather than one in managed recovery.

Cheers

Tim...

[adda.road@yahoo.com]

Hi Tim ,

How much time standby databases are behind the primary database?

why sometimes the standby databases are getting delayed to apply redos?

how to overcome such situations?

Thanks in advance.


Rampa.

[Tim...]

Hi.

There are a number of reasons why a standby database can lag behind a primary including:

- The standby server is a lower spec machine that can not keep up with the load on the primary server.
- The standby apply services run as a single process. As such, it can't compete with the multi-process processing on the primary server.
- The lag can be purposefully configured.

The solution to the lag problem depends on what the cause is. Impossible for me to comment. Some solutions may impact the performance on the primary database.

Cheers

Tim...

[adda.road@yahoo.com]

Hi tim,

Thanks a lot for reply.

rampa

[Tim...]

[adda.road@yahoo.com]

Hi Tim,

Which parameter differentiate whether it is Primary Database or Physical Standby Database or Logical Standby Database?

Which parameter we should change for standby databases to differntiate from primary database?


Thanks in advance.

Rampa.

[Tim...]

Hi.

This question shows a fundamental mis-understanding of what standby database is and the differences between logical and physical standby.

You need to do some reading and try to understand this functionality before firing out shotgun questions.

Cheers

Tim...