Yeah, at a glance it seems they had a performance problem, possibly from their use of reject and filter which you correctly guess operate over the results inste

Yeah, at a glance it seems they had a performance problem, possibly from their use of reject and filter which you correctly guess operate over the results instead of becoming part of the query. I'm guessing he was not familiar with the codebase and maybe not even ruby/rails in general and just wrote the whole sql query by hand, not bothering to figure out the correct way of parametrization , using string interpolation instead.