A typical scenario of usage of CLONE table.

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

I know the attributes of clone table and how it works, but I cannot find a typical scenario of usage of CLONE table.
Can you experts provide me one?
when and under what circustances should CLONE tables be used?
How will CLONE tables provide us benefits?

Thanks.

GuyC · Posted: Thu Feb 10, 2011 1:25 pm

1) Online processes fill a table, batch process empties it.
2) Information wharehouse tables are prepared/filled in clones.
during this process IW is still up
when the whole IW is ready, switch is made

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

GuyC · Posted: Fri Feb 11, 2011 1:39 pm

This briefly describes it : it.toolbox.com/blogs/db2zos/the-clones-are-coming-the-clones-are-coming-with-db2-9-15271

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

Thanks, GuyC,
Although the link you provided is just a brief introduction to Clone table, which can be found in IBM redbooks, thanks all the same.

One question:
It is mentioned in the link that:
<blockquote>While you are accessing the base table, the clone can be loaded with new data. When the clone is ready, it has all the data you intend to load loaded, the base table and clone table are switch. The new SQL EXCHANGE statement is used to force the switch. Once the EXCHANGE completes, all references are now to the clone, which is now actually the real table. </blockquote>

I want to ask, if you UPDATED the base table before the SQL EXCHANGE, what will be the result? Will the UPDATED data exist both in the clone table and base table after the execution of SQL EXCHANGE？？？

GuyC · Posted: Mon Feb 14, 2011 2:25 pm

no data that is inserted/loaded is only in clone table.
after exchange the clone is the base and the base becomes the clone. so that data exists in the base and not in the clone.

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

then, how to keep sync between base table and clone table?

GuyC · Posted: Mon Feb 14, 2011 6:53 pm

You don't. That's not what they are for.

dick scherrer · Posted: Tue Feb 15, 2011 12:52 am

Hello,

This sounds like another solution (clone table) in search of a requirement.

What do you need to do? If you explain what requirement you are tyring to accomplish, someone will probably be able to provide some alternatives.

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

I mean, if there is no sync relationship between base table and clone table, "CLONE" just provides convenience no more than existing function called "INCURSOR LOAD", which should not be the fact, I suppose.

dick scherrer · Posted: Tue Feb 15, 2011 7:59 am

Hello,

If you have no actual requirement, your time will be better spent elsewhere. . .

Is there no "real work" to be done

d

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

I just want to prepare for urgent requirement...

GuyC · Posted: Tue Feb 15, 2011 2:20 pm

I guess you didn't have to deal with many locking problems.
or with a set of tables establishing a consistent whole.

Loading a set of tables can be a lengthy process, exchanging clones isn't.

Cloning doesn't supply new functional solutions, only other ways to do the same faster and with better availability.
fe. There are sites which have views on one table that they change to another table and back. Cloning can do the same, but without invalidating packages.

dick scherrer · Posted: Tue Feb 15, 2011 8:29 pm

Hello,

singhju · New User Joined: 01 Dec 2010 Posts: 25 Location: Gurgaon

Hi,

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

I'm thinking of below question:

What if base table changes need to be applied to clone table?

GuyC · Posted: Wed Feb 16, 2011 2:14 pm

again : not what clones is about.

Clones are not copies, they are identical structures !

If you're looking for replication or mirroring solutions, do not look at clones.

dejunzhu · Active User Joined: 08 May 2008 Posts: 390 Location: China

Sorry, my mistake...
Thanks. GuyC

GuyC · Posted: Wed Feb 16, 2011 2:38 pm

np, you're not the only one that makes it. I had to tell this to several people, that's why I come over short.