Does overfeeding reduce the query performance?

[mce]

Hi,

I am trying to understand if overfeeding reduces the query performance in a cube that has rules.

Ideally my feeders should be conditional to avoid overfeeding, but to improve the time it takes for re-processing feeders (while loading cube into memory, or saving a rule) and to enable multi-threading for this, I used unconditional feeders which obviously resulted in some overfeeding. Since I do have a lot of memory in 64bit machine, I did not worry about additional memory requirement. But I could not achieve a very good performance for querying the cube, and I am wondering if overfeeding caused this performance degradation.

My hypothesis is that since I am feeding some cells that are not needed to be calculated (as any calculation will turnout to be zero for them), potentially I might have caused more cells than needed to be evaluated for calculation through overfeeding, which obviously reduces the query performance.

Any comments by experts will really be appreciated.

Regards,

[Steve Rowe]

Hi mce,

Overfeeding your calculation space will certainly reduce the performance of your calculations for exactly the reason you state, i.e. the engine is spending time evaluating zero cells.

The level of impact that this is having though is impossible for me to answer as I don't know anything about your model.

Getting the balance between rule saving / server starting and query performance can be a challenge but in my opinion query performance should be treated far more importantly than the other pieces. We should be building systems that are good for users not the people that maintain them.

The only way you can tell if it's worth doing is to actually do it I suppose, but you can make a judgement about how much you are over feeding, if it's only 10% it may not be worth the effort. If it's 30-40% I'd be trying to find the time to refine my feeders and so on.

Cheers,

Steve

[mce]

Hi Steve,

Thanks for your comment. I totally agree with you that user experience should certainly be a higher priority than administrator experience.
I would like to mentionthat Admin experience was not the only reason for the to avoid conditional feeders. Since the cube is being updated very frequently (in minutes) and since I use ReevaluateConditionalFeeders=T in Tm1s.cfg, having conditional feeders will also impact the time it takes to do the frequent cube updates.

Your response confirms my hypothesis and that means I should look at reducing overfeeding to improve user experience.

Regards,