Re: Convert SAP Oracle Database to IBM DB2 Database??

On Feb 6, 5:46 pm, Noons <wizofo..._at_yahoo.com.au> wrote:
> On Feb 7, 4:29 am, Jeroen van den Broek
>
> <nlt..._at_baasbovenbaas.demon.nl> wrote:
> > Never done it myself, but you may find this whitepaper of interest:ftp://ftp.software.ibm.com/software/data/pubs/papers/DB2-SAP-compress...
>
> you know what is amazing in this paper?
> How it shows improvements in CPU in the application server
> when the db server gets compressed rows!
> Must be an amzing "feature", this compression that
> can change the performance in a different system...

I haven't bothered to read the paper, but if you think about it, changing the performance of a system can affect the performance of another system. Thought experiment: app server spends lots of cycles processing data coming through the network, starving the cycles needed to process local processes. Slow down the data coming through the network by making the db server slower processing decompression from db, more cycles available to process local work.

Of course, if there is sufficient power in an app server, feeding it more data from the db server will show up as better performance too. That ought to be obvious.

[Glances at paper] I only see one system in the paper, am I missing something? Also looks like they didn't really push the envelope to a point where compression bottlenecks really would show up ("...investigation should go deeper in future." - well, duh), though maybe I didn't look closely enough - if they had started with cpu usage close to the edge, things certainly would have gone south fast. As shown, I would guess for full-table-scan type batch jobs the decrease in scan time is much greater than any increase in cpu time - which seems to be the point.

Since most systems I've seen are eventually pushed to their limits, I think this sort of trade-off can bring the day of necessary hardware upgrade closer. But maybe the DB2 world is different.

jg

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