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Re: Db2, Oracle, SQL Server

From: Serge Rielau <>
Date: Thu, 10 Feb 2005 09:12:53 -0500
Message-ID: <>

Valentin Minzatu wrote:
> I still cannot recollect which IBM document I've seen where it was stated
> that DB2's HA feature does not replicate DDLs or some of them, but I will
> get back once I find it. Consider this one closed for now.
Whatever it was the doc was faulty.
The only place where one has to be careful is with LOAD. It must be a recoverable load and the copy must be on a shared filesystem/TSM.

> Per my understanding: DB2 partitions the data at the cluster level (must you
> have a cluster, parallel server?), therefore each node has its own data and
> when the query is submitted, one node acts as a dispatcher while the others
> execute it and then the results are merged in memory. Oracle allows for this
> as well, but it does not impose it as a limit. One could easily execute the
> same query in a serial manner (i.e. one single server process retrieves all
> the data querying each partition). The advantage is that if one of the nodes
> go down you do not need to repartition the table or move data around at all.
> It is already available as it is shared by all nodes. - please correct me if
> i am wrong - I would also like to know if DB2 has the ability to exchange
> partitions without taking the table/partition offline.
I don't kno whwat the latter means, and I have in detail talked about the first point. It is irrelevant whether DB2 requires all the nodes up or not as long as a node can fail over similarly quick as it takes e.g. RAC to evict a node (which is not free!) It is unreasonable to require two DBMS to use the same Technology(tm). It is reasonably to except the same end result. What matters is whether a DBMS can scale, perform, has HA, .... and what the TCO of it is.
Any more low level metric means buying into a vendor's marketing labels.

> I couldn't find the Oracle's document you refered to (maybe they hid it
> ??). - i have just removed the rest of this paragraph as they could have
> caused some flames :)

The doc on PSM support? It's in the SQL Ref.. Maybe your browser couldn't handle the wrapped line for teh URL?

> ASM is there since 2004 - when they launched 10g, and one of the biggies
> about it is that one can transport tablespaces from one DB to another
> independent of the O/S (neat, huh?).

Yes. Only a fool claims that everything the competition has is bad by definition. I'm no fool - I think :-)
Know your strengths, know your weaknesses. Know the same about your competitors...


Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab
Received on Thu Feb 10 2005 - 08:12:53 CST

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