diatribe vs pat on the back

diatribe

noun
  • A speech or writing which bitterly denounces something. 

  • An abusive, bitter, verbal attack or criticism: denunciation. 

  • A prolonged discourse. 

pat on the back

verb
  • To praise or congratulate. 

noun
  • Praise, congratulations. 

How often have the words diatribe and pat on the back occurred in a corpus of books? (source: Google Ngram Viewer )