* https://wiki.postgresql.org/wiki/Slow_Query_Questions
  * https://wiki.postgresql.org/wiki/Logging_Difficult_Queries
  * Analysers:
    * https://github.com/WoLpH/pg_query_analyser
    * pgbadger (debian pkg) -> couldn't make work
    * pgfouine (debian pkg) -> couldn't make work
    * http://explain.depesz.com/