If you use a simple formula, and block size is not unusually large, you can place the formula on a member of either a sparse or a dense dimension without significantly affecting calculation performance. The bigger the block size, the more impact simple formulas have on calculation performance. For a discussion of the relationship between block size and calculation performance, see Block Size and Block Density.
A simple formula is, for example, a ratio or a percentage and meets the following requirements:
Does not reference values from a different dimension (sparse or dense). For example, a simple formula cannot reference Product -> Jan.
Does not use range functions. For example, a simple formula cannot use @AVGRANGE, @MAXRANGE, @MINRANGE, or @SUMRANGE.
Does not use relationship or financial functions. For example, a simple formula cannot use @ANCESTVAL, @NEXT, @PARENTVAL, @SHIFT, @ACCUM, or @GROWTH. For a complete list of relationship and financial functions, see the Oracle Essbase Technical Reference.
For information on how formulas affect calculation performance, see Bottom-Up and Top-Down Calculation.