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DB2 V9.1 Backup tablespace and restore to different tablespace with lower page size.

I have a db2 aix tablespace in which the tables requiired no more then 4k page size. Is it possible to create new tablespace(4k) / backup the 16k and then restore to the new tablespace?? Is there a implied constraint in the process.


Thanks.
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excitable
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excitable
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Kent OlsenData Warehouse Architect / DBACommented:
Hi excitable,

I'm not sure where the '16k' figure came.  Is that the page size in the original table?

As long as the container (tablespace) doesn't change, you can always back up a DB2 database on a server and restore it (as is) to a similar server.  (You can't restore a windows backup to Z/OS, etc.)

If the underlying container is going to change (e.g. you're going to change the page size) you need to be a bit more creatiive.  DB2 will have to build the tables, not just restore them.

I'm curious about the decrease in page size.  If the database does a LOT of random I/O, the smaller page size could get you better performance.  But in my experience, the larger page size is almost always a winner.


Good Luck,
Kent
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excitableAuthor Commented:
Sorry for being unclear. I have a 16k page size tablespace that I want converted to a 4k page size. I am getting a huge amount of logical i/o and bufferpool thrashing. None of the tables maxlength exceed 4k. Can I do what I want with a tablespace restore or do I have to do a database redirected restore? I guess another way to say this is there an 'into' clause for tablespace restores??
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Kent OlsenData Warehouse Architect / DBACommented:
Restoring a tablespace 'into' another tablespace won't address the page size issue.

The biggest 'problem' (and it's not really a problem) is that if you're going to change page size, you're going to change the physical location of data.  Rows wind up in different pages and will be keyed differently within those pages.

I'm not aware of any IBM utility that will restore the data to a different page structure and rebuild all of the related entities (indexes, etc.).

I believe that you'll have to create a new table with a 4K page size and load the data into it.  Of course, you'll have to make sure that all of the indexes, triggers, RI, etc. are defined for the new table, too.


Kent
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excitableAuthor Commented:
Thank you for the help.
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