Measure dimensions go last?

[ebt5]

I'm new to TM1 and am re-ordering dimensions in our cubes to minimize memory usage. I read that the measure dimension should go last, especially if it is a string dimension, but I can get huge memory reduction in a couple of cases by moving it. What is the advantage of having it last, and why especially when it is a string dimension.

Thanks in advance for any enlightenment.

[David Usherwood]

TM1 doesn't have the concept of a string dimension as such. Dimensions can contain numeric and string elements. _If_ the dimension is the last one in the cube, then you can store text against the string elements - and if the last dimension has string elements, you can't resequence it. (To my considerable surprise I found that Joe Puzstai had - inadvertently I'm sure - not spotted this when he set out the TM1 Best Practice guidelines.)

So if your 'measure' dim doesn't have strings, move it by all means. If it does, it won't move.

BTW, TM1 doesn't really have the concept of a measure dimension for itself. You can mark a dimension as a measure dimension and I believe other tools will use it though I've never spotted how. TM1 doesn't care, subject to the issue above.

HTH

[Martin Ryan]

Hi,

TM1 uses the last dimension to determine whether a cell is a string or N level element, therefore if you want to have string values in your cube this dimension MUST go last.

If you don't want to have string elements then it's mainly just a best practice thing, which I think is still down to the strings thing - if you want to have strings one day, then in order to be future proofed you must have the measures last.

If you are 100% certain that you'll never ever want to have strings in your cube, then there is no technical reason why you can't have the measures dimension anywhere in the dimension order.

HTH,
Martin

[ebt5]

Extremely helpful. Thanks for explaining the reasons behind the best practice. I have a couple places where the data is fundamentally numerical and it is helpful to know I can cautiously move that dimension to shrink memory requirements.

Thanks a million!