A big thanks to all those who braved attending my session on the final day of Oracle Open World 2014. I hope you enjoyed it and found it valuable.
You can download the slide deck as well as the scripts I mentioned here.
As always, I would love to hear from you.
Another early start on Wednesday. I headed down to meet the Dbvisit gang for breakfast. FYI: I’m not paid to keep mentioning them and I don’t work for them. They are just a great group of people who I really like, so when I get a chance to meet up with them I do.
Tuesday started early with 5 hours in the hotel lobby. The plan was to catch up on my blogging using the free wifi. I hadn’t blogged for a couple of days, which prompted an email from my mom to see if I was OK.
It took about 5 hours to complete two blog posts, because every 30 seconds someone new walked by and I was “forced” to speak to them.
That done, I headed down to Moscone South to check out the Dbvisit stand. I mentioned a few weeks ago that I had never tried a Twinkie, so Chris Lawless went to work correcting that state of affairs by bringing a box of Twinkies to their stand. You can see me trying my first Twinkie here!
In a comment on my previous post on shrinking tablespaces Jason Bucata and Karsten Spang both reported problems with small objects that didn’t move to the start of the tablespace. This behaviour is inevitable with dictionary managed tablespaces (regardless of the size of the object), but I don’t think it’s likely to happen with locally managed tablespaces if they’ve been defined with uniform extent sizes. Jason’s comment made me realise, though, that I’d overlooked a feature of system allocated tablespaces that made it much harder to move objects towards the start of file. I’ve created a little demo to illustrate the point.
Monday started with the San Francisco bay swim. I was actually pretty scared about doing this. I like to swim, but I’m a child of the “Jaws” generation, so open water is not my thing! Added to that, the water is cold. The coldest my training pool ever gets is 25 degrees C, which feels quite cold. The water in the bay is unseasonably warm at 19 degrees C. For anyone that doesn’t know, that means it is damn cold!
Sunday started with the walk across the Golden Gate Bridge. It was meant to be a run, but a few of us lazy folk met up early and walked it instead. I did run about 5 paces, so I don’t feel quite so guilty about having a “I ran the bridge” type T-shirt.
Especially on this Monday it seems all about new database data intern ration technologies and…
It’s been about 8 months since I posted a little note about a “notable change in behaviour” of the optimizer when dealing with subqueries in the where clause that could be used to return a constant, e.g.:
select * from t1 where id between (select 10001 from dual) and (select 90000 from dual) ;
There’s been a note at the start of the script ever since saying: Check if this is also true for any table with ‘select fixed_value from table where primary = constant’ I finally had a few minutes this morning (San Francisco time) to check – and it does, in both 184.108.40.206 and 220.127.116.11. With the t1 table from the previous article run the following:
Thank you all those who came to attend my session "Demystifying Cache Buffer Chains Latches" at Oracle Open World 2014. Much appreciated. I hope you got something out your time investment.
I have also written a paper to accompany this session. The paper explains the concepts I presented in greater detail. You can download a zip file containing the slide deck, the paper and the scripts here. Please note: this is a zip file.
And, yes, here is the blog entry that talka about why you need 7X memory to completely fit your database in buffer cache http://arup.blogspot.com/2011/04/can-i-fit-80mb-database-completely-in.html
As always, I would love to hear about your thoughts on the presentation.
One down at #oow14; five more to go :)