Hello,
I often use CTE's or views to create faux parameters as a way to improve reusability of code. For example, if I had a bunch of CTE's or subqueries (or different queries/views altogether) that all used a common value in a where clause, I would simply create a view/CTE containing the values and select the values from a subquery wherever needed. This typically has no meaningful impact on performance; however, it seems to degrade execution speed quite a bit in Athena and I'm not sure why this would be the case. What is the difference between: 'select * from table where foo = 'bar' versus 'with param as (select 'bar' as p) select * from table where foo = (select p from param)'? When querying a substantial amount of data, the second pattern makes the query speed untenable. These tables are partitioned to the hour also.
