In this section:
In nearly every real life situation, the database size needed for PMF is determined by the size of the core MEASURES table in the PMF Data Mart. In PMF, the MEASURES table stores the basic facts about your Measures. The actual formula for determining the size of the MEASURES table is:
SIZE in bytes = (average number of bytes per row) * (count of rows)
To determine the size of a row in the Measures table requires some deep knowledge about your particular RDBMS. The most simplistic method is to add up the number of bytes used by each column in the table and any indexes, and then add a few more bytes for overhead.
As of PMF 5.2.2, if you allow 4 bytes per Integer field and 8 bytes per floating point field, the MEASURES table is slightly over 200 bytes per row. Additionally:
The number of rows in the PMF MEASURES table in the Data Mart is determined by your business requirements. For some requirements, a few thousand rows of data is sufficient; other business requirements may require millions of rows.
If you are unsure of your business requirements at the time you are performing an estimate, the recommended approach would be to:
Suppose you are measuring your metrics at the monthly level. You have a total of 100 Measures, you want to store three years of data, and you are loading a sample cross section of 20 Measures. After your initial loads, you can run this query on your PMF Data Mart from a SQL tool or from WebFOCUS:
TABLE FILE PMF_CUBE_VW WRITE CNT.MEASURE_ID BY TIME_LEVEL01_VALUE BY TIME_LEVEL02_VALUE BY TIME_LEVEL03_VALUE END
Your results would look something like this:
MEASURE_ID Year Quarter Month COUNT ---- ------- ----- ---------- 2010 1 03 101817 2 04 111662
This indicates that you are loading an average of 105K rows per month. Since your sample cross section was 20% of the total Measure population, multiply that result by 5 to get the total average number of rows per month.
You would then multiply that by 36 since you are planning to store three years worth of data. This yields 105K * 5 * 36 = 18900K rows of data - or 18 million rows.
You need to make sure that enough disc storage space is allocated on your WebFOCUS server to allow PMF data loads. Typically, you need to make sure there are about 32GB of free storage space to avoid having any problems. If you want to calculate the amount of storage space needed more precisely, use the following formula:
[MAX Number of rows for Measure] x [MAX Number of linked Dimensions] x [MAX levels] x 30 x 4 bytes
For example, if the largest Measure load is 2 million rows, linked to 16 Dimensions that each have 16 levels:
[2M] x  x  x 30 x 4 bytes = 62GB bytes of temp space needed
Note: After each load, the WebFOCUS server clears this temporary space so you do not need to multiply by the number of measures.