|based on revision 61 of SAP HANA and SAP HANA Studio|
Recently I looked into the execution of a simple information model and discussed it with some fellow CSA guys.
While I was delighted to see how well PlanViz reports all the internal stuff, my colleagues complained that they couldn’t see the information I was talking about. They had to resort to unsupported, undocumented and generally, evil tools and techniques to find the same information (yep, HDB xxxxxx 🙂 ).
So what was going on?
The SQL under examination was a simple SELECT like this:
GROUP BY “FIELDA”
The referenced calculation view is a scripted calc. view that does nothing but a simple projection from a base table.
So far so good.
This is what my colleagues saw:
Easy to see: the time is spent in the ceAggregationPop!
But, wait a minute… where do we access the base table?
There’s something missing here.
However, when I executed the same query and displayed the visual plan I didn’t miss any information.
It was all right there:
So, for my enhanced expert mode-enabled SAP HANA Studio, PlanViz obviously had a lot more to tell.
All good, except:
I don’t have a SAP HANA Studio that is any different from the one everybody else has.
Also, when checking the generated XML text (simply open the .plv file in your favourite text editor) the additional information was always there.
We had been on the brim to open a support message when I went through the whole thing again and found that it must be a feature/ behaviour on display level. Something in the PlanViz UI must decide to show or hide the information.
As I didn’t find any option to select the display style in the PlanViz perspective I reviewed the Settings menu and got lucky:
Starting with SAP HANA Studio revision 60 there is a new settings category for PlanViz.
In the Parsing settings screen, it’s possible to switch on or off the display of sub-execution-plan-pops (POP = plan operator).
Unfortunately, the option is labelled just “Remove the children of CeSqlPop Node“, but apparently it works also on CeAggregation nodes.
By un-selecting this hide option (who doesn’t like double negatives to add information?) and re-executing the PlanViz for the statement the additional information are now displayed nice and well for my colleagues, too.
There you go! Now you know! 🙂