TM1 Design Pro-Style: Rules vs. TI
If you’re a TM1 user, you know rules are how you work business logic into your model. You probably calculate things like salaries and sales, and you may even have more complex calculations in your model such as exchange rates and allocations.
Since TM1 calculates rules on the fly, your data adjusts continuously as you enter new information into TM1. This is a powerful advantage TM1 brings to your planning and analysis needs—no need to run scripts, or wait overnight to see your results!
One of the questions that comes up often:
When should I use rules, and when should I use Turbo Integrator, TM1’s ETL tool?
First, let’s review the basic capabilities of Rules and TI. The following table summarizes some of the key functionality of each.
Here are some things to keep in mind when deciding whether to utilize rules or TI:
Do you want to pull the trigger?
Scenario 1: You’re updating FTE’s in your headcount model, and you want to analyze the impact of various hiring plans on the bottom line. You are making a presentation for the management team that afternoon.
Solution: This should be rules. Rules calculate on the fly, allowing you to view the impact of your changes immediately within the model.
Scenario 2: Your planning cycle is sequential: first, the revenue team finishes their numbers, and then, the expense forecast is calculated based on the revenue forecast. You want to be sure the revenue numbers you’re working with are not changing, so that your cost assumptions are in line with the current version of revenue targets.
Solution: This could be either rules or TI: if you prefer the model to calculate live, you can flip the revenue numbers to read-only once they are finalized to ensure the numbers don’t change. Or, you may prefer to “pull the trigger” and load the final revenue numbers into the expense model to be utilized as drivers. Use Turbo Integrator if you want full control over calculation changes.
How dynamic is the data?
Scenario 1: You are loading actuals from your ERP system, but you want to load them into both local currency and USD (a common scenario, since many ERP systems don’t support Fx at the ledger level.)
Solution: Use TI. Since these numbers are actuals, the Fx calculation only has to be done one time. So, no need to calculate on the fly. TI can do the conversion while loading the data, and load into both local currency and USD.
Scenario 2: You have cost allocations in your forecast to calculate a contribution margin by product.
Solution: Since your forecast numbers will change frequently, use rules to allow you instant access to the results.
Is traceability important to you?
If you want users to be able to trace how a number was calculated, then rules are the way to go. Tracing the calculation path for rules is a built-in feature, that is not available for TI-generated data.
What type of calculation is it?
Rules are amazing at performing millions of calculations on the fly, with only a line or two of code. The simplicity of a rule like Sales = Price * Units is very powerful in TM1, as, with just this one line of code, it will calculate across all products, months, regions, etc. If you have a calculation that is iterative, depends on variables that might change, needs a counter, or other such programming logic, though, you may be better off with TI, which has the normal programming options open to it.
Note on performance
There are performance considerations for Rules and TI, as well. It’s important to factor these in before making your final determination. TM1’s capacity for data is enormous, but you may have limits in the short-term based on the CPU and RAM on your server. So, if you’re not sure about the performance impact for a more complex, or large-scale calculations, make a proof-of-concept rule (don’t forget the feeders!) to gauge performance impact.