testing infrastructure: parameterize output file suffix
testing infrastructure: checking print output
PrintRecord -> PrintCSV
generate actual csv

- added yldHd to avoid cluttering with if -- too complex? at least,
  shows that all this yielding is pure staging

- caveat: csv invalid b/c of compilation: ok noise
precompile query, so that csv output does not have compilation: ok noise, also might be useful later for benchmarks