[SOLVED] Guided Decision Table and Guided Rule has same ruleflow group. Which rule would get executed first?

Guided Decision Table and Guided Rule has same ruleflow group. Which rule would get executed first?

I have a Guided Rule file that sets a configuration for some convergence factors. Later I have a Guided Decision Table which has the same rule flow group. Even when I don't mention any salience in both these files, the Guided Rule gets executed first and sets the configuration value, and the same model is later imported in the Guided Decision table and these default values are set in Guided rule are used in the Guided Decision table.

Is there a specific reason "why guided rules get execute first and guided decision tables gets executed later, even though they have the same rule flow group"

Solution

Unless you're using saliences, execution order is non-deterministic. There are no guarantees that Rule A will always go before Rule B. It might always go in this order (A -> B) right now, but that's not guaranteed, and tomorrow or the next time you do a rules change or a version update, it might go in a different order. It usually has to do with the order that rules are loaded into memory, (which is why un-salience'd rules in a single DRL file tend to be executed top of file to bottom of file, because that's the order they're read.)

If your rules are such that you require them to be executed in a specific order, you should put saliences on them so that Rule X will always execute before Rule Y because of the saliences on them. Alternatively, you could rewrite your rules to not rely on execution order (this is considered good practice anyway.)

The only order guarantee that Drools provides is that rules of a given salience will execute at the same time, though the order of those rules within the salience is not guaranteed. Rules with no salience are all defaulted to salience 0, so this guarantee holds true. All of the rules execute, but no order is guaranteed and cannot necessarily be consistently determined ahead of time (hence "non-deterministic.")

So really, at the end of the day, when your question is "which rule gets executed first?" the answer is -- unless you have saliences, it shouldn't matter. And if it does matter, you need to fix your rules.