Tom Kyte's prequel to Guru4Pro

Yesterday over 100 Pro's attended Guru Tom's session on '11 Things about 11g'. But in the hours before that session a small number (about 18) of persons had the honor of listening and discussing with the master himself. As a guide he used an extensive version of his 'Worst Practices' presentation. During - and after - the presentation there was a lot more Q&A than I've experienced in regular sessions - of course due to the small scale of this session.
On a question about the new features and enhancements of 11gR2 Tom told that there will be no export functionality anymore in R2 (import will be available though). For moving data from one instance to another you should use datapump or SQL Developer or APEX. Also he explained a little more about the Online Application Upgrade. This feature will use invisible indexes, cross edition triggers and (a maximum of) two versions of PL/SQL programs and views (tables are not versionable). It sounds like it is not a black box feature, but needs some programming to get things working. By the way, in 11gR1 this functionality is already available and you can turn it on using some hidden initialization parameter (I don't know which). You can see the column edition_name is there in the all_objects view..... 11gR2 is expected to be available in 2009Q1!
For all APEX developers: Tom, as expected from a database man, is truly an APEX supporter - he mentions the power of APEX a lot during his presentations!

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Filtering in the APEX Interactive Grid

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Stop using validations for checking constraints !

If you run your APEX application - like a Form based on the EMP table - and test if you can change the value of Department to something else then the standard values of 10, 20, 30 or 40, you'll get a nice error message like this: But it isn't really nice, is it? So what do a lot of developers do? They create a validation (just) in order to show a nicer, better worded, error message like "This is not a valid department". And what you then just did is writing code twice : Once in the database as a (foreign key) check constraint and once as a sql statement in your validation. And we all know : writing code twice is usually not a good idea - and executing the same query twice is not enhancing your performance! So how can we transform that ugly error message into something nice? By combining two APEX features: the Error Handling Function and the Text Messages! Start with copying the example of an Error Handling Function from the APEX documentation. Create this function

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