Entries in Event (3)
Tanel Poders - Snap it!!!
Karl Reitschuster
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Tanel Poder holds a 2 day session in Düsseldorf last week; This was not my first Tuning/Troubleshooting training. But it was extraordinary what Tanel showed us when usual ways would not work
Enterprise Management Reporting for SAP R/3 - in 72 hours - (Frankfurt/Dreieich 25th of June)
Karl Reitschuster
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Updated on Thursday, July 5, 2007 at 10:24PM by
Karl Reitschuster
Dear reader, SAP comes with an own Datawarehouse solution for SAP R/3 called SAP BW. SAP BW due to it's complex source system and the amount of data and structure is very complex to handle. To startup a DWH Solution for a SAP R/3 customer development round trips for getting first reports out of the system lasts for weeks or even for months. And so the costs for customizing a SAP BW are high.
Tough three days with Jonathan Lewis (Bonn 12th-14th of June)
Karl Reitschuster
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Dear reader,
i was able and indeed very happy to visit three sessions Jonathan Lewis did this week in Germany. It was a lot of very interesting stuff with a high input rate;-)
- Cost Based Optimisation, 12. Juni 2007
- Trouble-Shooting and Tuning, 13. Juni 2007
- Writing Optimal SQL, 14. Juni 2007
I do not want to give a summary report about every session but i do want to write three follow ups about one aspect per day i found very interesting and i did not know or did not see it that way before.
And i want to provide a (very) small picture gallery of the event.
Another interesting point was is to meet a lot of folks working with Oracle in a different way and to share experiences.
Karl Reitschuster
Karl Reitschuster
Cost Based Optimisation, 12. Juni 2007 - The Truth about sorting
For every one of the three days i wanted to post a highlight of understanding Jonathan Lewis gave to us about the oracle server :
When Oracle sorts data - hopefully in memory - it does not sort it at all! Data to sort is loaded as it is into the sort area. How then it will be sorted?
For every row loaded into the sorting area oracle creates a branch in a binary tree. This tree structure grows and so also demands place in the sorting area. The binary tree is linked with Pointers.
- This in mind helps you to understand that not all memory allocated for sorting is used by the data but also by it's tree memory structure and some little piece of metadata. So allocated for sorted data could be larger as assumed.
- On 64 bit Machines the pointer for the binary tree are also 64 bit sized - therefore you need even more memory to sort the same amount of data as on 32 bit machines.
The binary tree was replaced in Oracle 10.2 with a more CPU saving hash structure.
Karl Reitschuster
Karl Reitschuster
Trouble-Shooting and Tuning, 13. Juni 2007 - The Truth about Tuning
if you are called for Tuning very often you are called for running production systems having tremendous problems keeping service times. Is this not the broad understanding of Tuning?
Jonathan Lewis pointed out that this kind of emergency job is Trouble-Shooting and not Tuning. Tuning happens in the development process. If you are called for Trouble-Shooting on a live system you missed something very important in the development/design phase.
Karl Reitschuster
Karl Reitschuster
Jonathan Lewis repeated to proclaim : Hints are never ignored by oracle if they are written correctly and if the object exists if one is specified. Hints are rarely documented. It's not clear what strategy or pattern is behind a hint. One example:
SELECT /*+ PARALLEL(CUSTOMER, 8)*/ * FROM CUSTOMER;
Karl Reitschuster
