When to use Do Not Store

[BeckyMN]

Hi again,

As long as I'm admitting my serious lack of knowledge about certain aspects of FileMaker I'll ask another question that I really should already know the answer to but haven't found the time to really understand.

Whenever I define a calculation field there is option under the storage options tab that allows me to choose "Do not store calculation results -- recalculate when needed". I really don't understand when to check that box and when to leave it alone. On everything I have done so far it doesn't seem to matter whether I check the box or not. FileMaker displays the correct results.

Can somebody tell me under what conditions I should check the box and when should I just let it be?

Thanks again,

Becky

[LaRetta]

Hi Becky,

If a calculation involves fields which all reside within the same RECORD (FieldA, FieldB...), it doesn't need assistance in updating itself. Whenever one field (within the calculation) changes, the change becomes a trigger and forces the calc to re-evaluate. But if a calc refererences fields from another table, Get() functions, aggregate functions, globals or other unstored calcs, then FM doesn't know these changes have happened and it needs help. Calculations can't see other records within the same table; nor can it see other tables' records.

So to assist FM, making a calculation unstored, allows the calc to be hypervigilent. Each time an unstored calc is displayed, FM re-evaluates it.

LaRetta

[Lee Smith]

Search your Online Help for [color:blue]Unstored

And then, select

[color:blue]

Defining field indexing options

Lee

Edited December 16, 2005 by Guest

[comment]

This can be sometimes a complex issue. Until you understand it better, I would suggest this practical rule:

Leave the calculation at its default state, i.e. stored. Filemaker will automatically change it to unstored when it relies on related or global fields.

The one exception is when you use one of the Get() functions, e.g. Get(CurrentDate). Then you have to tell Filemaker to make the calculation unstored, so it will update when the date changes.

[BeckyMN]

Hello again,

I would like to say a belated thank you to all of you who provided an answer to my question! This truly helps me a lot. I'm sorry I couldn't say thank you sooner but the Christmas holiday really took over my life for a while.

Sincerely,

Becky