Add A Filter For Pivoted "Percent of Row" Calculation

[Oluchi]

I am trying to create a filter so that my dashboard users have the ability to filter out servers with a low sample percentage. My data is sample percentage over time, pivoted by server name.

Initially, I calculated sample percentage by using the 'percent of row' table calculation on my 'count distinct' measure. I ran into trouble since you can't add a filter for table calculations. I tried to create a custom filter, but 'count distinct' is a measure and thus I can't.
So, I created a measure within lookml that calculates the percentage sample for me:

measure: percent_of_dvc_count {
sql: ${count_distinct} / SUM(${count_distinct}) OVER (PARTITION BY ${time});;
type: number
value_format_name: percent_0
}

This works, but when I try to filter on this within my explore I get the error:
Analytic function not allowed in HAVING clause at [104:67]
for this line in question in the SQL query that Looker has created:

HAVING ((( (COUNT(DISTINCT bq_ookla_overview_view.id )) / SUM((COUNT(DISTINCT bq_ookla_overview_view.id ))) OVER (PARTITION BY (FORMAT_TIMESTAMP('%F %T', bq_ookla_overview_view.ts_rslt , 'America/New_York'))) )) > 30))

I again can't create a custom filter on my measure since it's a measure. So I tried to define a filter directly within lookml as follows:

filter: percent_over_five {
type: yesno
sql: (${count_distinct} / SUM(${count_distinct}) OVER (PARTITION BY ${time})) > 0.05 ;;
}

But I then receive this error:
invalidQuery: Aggregate function COUNT not allowed in WHERE clause at [89:296]

Is there any way to achieve this filter? I need the window function or my percentage isn't accurate. Even when I move SUM(${count_distinct}) OVER (PARTITION BY ${time})) to a seperate intermediate measure, I still receive the 'having' error. 

[GavinW]

I think the way to resolve this is to make a dimension of the measure you are trying to apply the filter to. You can calculate the percentages in a derived table, join that back to your explore, and then the users can filter on the percentage exactly as they would any other dimension.