SQL/Active Record querying

sql_vs_ar

Benchmark.bm do |x|
  x.report("sql"){ 5000.times { Person.where(id:2).pluck("created_at").first } }
  x.report("sql"){ 5000.times { Person.find(2).created_at } }
end

 [#<Benchmark::Tms:0x000001065b1240
  @cstime=0.0,
  @cutime=0.0,
  @label="sql",
  @real=1.558864,
  @stime=0.11000000000000032,
  @total=1.120000000000001,
  @utime=1.0100000000000007>,
 #<Benchmark::Tms:0x007fb6f5aa6d98
  @cstime=0.0,
  @cutime=0.0,
  @label="sql",
  @real=2.011806,
  @stime=0.10999999999999943,
  @total=1.6899999999999995,
  @utime=1.58>]