I am able to easily create a summary field, using the LIST option to have a field that is always instantly populated with a return-separated list of the values from a designated field.
I thought I could filter the portal to refer to that found set by using PatternCount, but when I do that, the portal takes forever to refresh.
Here's what I am working with.
Example: the summary field "foundset" contains the following values for a field called ID:
In the portal filter, I have specified if ( PatternCount ( foundset ; ID ) > 0 ; True ; False )