Let's do this quick and painless!
From SPS 7 (rev. 70.00) SAP HANA doesn't automatically create concatenated attributes for multi-column-joins anymore.
BANG!
There you go.
Just asked for it ( Looking for more info on CONCAT_ATTRIBUTE, Free Space by Unload Columns or Alter Table for hidden concat_attribute columns... ) - just briefly after learning that these concat attributes were there in the first place - and now you got it.
Let's see how much better the HANA world will be now.
Of course everything comes with a price for it.
Multi-column-joins that are executed without these concat attributes will take more time compared to the cases where a concat attribute can be used.
In order to have concat attributes in place when you want them, you can simply create indexes on the tables covering the exact set of columns.
For multi-column joins defined in any of the information model views the activation of the view will still create the creation of the concat attribute and that makes sense.
All in all the big problem with these concat attributes was that they had been created automatically and didn't require any privilege for that.
Even in production systems one could fire a SQL statement with a join that would in turn lead to the automatic creation of two relatively large data structures.
On top of that these concat attributes where difficult to find and remove.
With the current setup this cannot happen any longer.
Nice.
Once I have more time again, I will provide an update/follow up to Playing with SAP HANA that provides more details and explanations.
But that's all for now folks.
Now you know!
Have a great holiday season, cheers!
Lars
