The optimum size of the calculator cache depends on the memory that the system has available and on the nature and configuration of the database.
Using the following formula, you can calculate the calculator cache size required for Essbase to choose each of the three options in Table 175, Calculator Cache Options:
Calculator cache = Bitmap size in bytes * Number of bitmaps
where
Bitmap size in bytes = Max ((member combinations on the bitmap dimensions / 8), 4)
and where
Number of bitmaps = Maximum number of dependent parents in the anchoring dimension + 2 constant bitmaps
The minimum bitmap size is 4 bytes. If (member combinations on the bitmap dimensions/8) is less than 4 bytes, Essbase uses a bitmap size of 4 bytes. |
Consider a sample database with five sparse dimensions (S1 to S5), as shown in Table 176:
Use this sample database for the following sample calculations:
For this sample calculation, assume the following facts about a database (from Table 175, Calculator Cache Options):
Bitmap size in bytes = (S1 * S2 * S3 * S4) / 8 = (20 * 20 * 50 * 50) / 8 = 125,000 bytes Number of bitmaps = Maximum number of dependent parents in the anchoring dimension = + = 2 constant bitmaps = 3 + 2 = 5 Calculator cache = Bitmap size * Number of bitmaps = 125,000 * 5 = 625,000 bytes
For Essbase to use multiple bitmaps for this database with one anchoring dimension, the calculator cache must be 625,000 bytes.
For this sample calculation, assume the following facts about a database (from Table 175, Calculator Cache Options):
Bitmap size in bytes = (S1 * S2 * S3 * S4) / 8 = (20 * 20 * 50 * 50) / 8 = 125,000 bytes Number of bitmaps = Single bitmap = 1 Calculator cache = Bitmap size * Number of bitmaps = 125,000 * 1 = 125,000 bytes
For Essbase to use a single bitmap for this database with one anchoring dimension, the calculator cache must be 125,000 bytes.
For this sample calculation, assume the following facts about a database (from Table 175, Calculator Cache Options):
Perform this calculation:
Bitmap size in bytes = (S1 * S2 * S3) / 8 = (20 * 20 * 50) / 8 = 2,500 bytes Number of bitmaps = Single bitmap = 1 Calculator cache = Bitmap size * Number of bitmaps = 2,500 * 1 = 2,500 bytes
For Essbase to use a single bitmap for this database with multiple anchoring dimensions, the calculator cache must be 2,500 bytes.