#!/bin/bash
#
# Plugin to monitor PostgreSQL Database Ratios (blocks read X blocks hit)
#
# Author:
#    Guilherme Augusto da Rocha Silva <gars.dba@gmail.com>
#
# Created:
#    5th of november 2007
#
# Usage:
#    Place in /etc/munin/plugins/ (or link it there using ln -s)
#
# Parameters:
#    config   (required)
#
# General info:
#    Require permission for database access and read (no writes are processed).
#    Recommended user is PostgreSQL database owner (default: postgres).
#
# Log info:
# 2007/11/30 - Review on comments
#

dbserver='localhost'
dbuser='postgres'

if [ "$1" = "config" ]; then
   echo 'graph_args --base 1000 --lower-limit 0 --upper-limit 100'
   echo 'graph_category db'
   echo 'graph_info Shows each database read/hit (%) on the PostgreSQL Server.'
   echo 'graph_scale no'
   echo 'graph_title PostgreSQL Database Hit/Read Ratios'
   echo 'graph_vlabel % of blocks read and hits'

   psql -h ${dbserver} -U ${dbuser} -tc "SELECT datname FROM pg_stat_database WHERE datname != 'template0' ORDER BY 1;" | while read name
   do
      test -z "${name}" && continue
      echo ${name}'.label '${name}
      echo ${name}'.type GAUGE'
      echo ${name}'.min 0'
      echo ${name}'.max 100'
      if [ "${name}" == "template0" ]; then
         echo ${name}'.info PostgreSQL template database.'
      elif [ "${name}" == "template1" ]; then
         echo ${name}'.info PostgreSQL and/or user template database.'
      elif [ "${name}" == "postgres" ]; then
         echo ${name}'.info User postgres database.'
      else
         echo ${name}'.info User defined database.'
         echo ${name}'.critical 50:min'
         echo ${name}'.warning 75:min'
      fi
   done
   exit 0
fi
psql -h ${dbserver} -U ${dbuser} -tc "SELECT datname||'.value '||(CASE WHEN (blks_hit > 0) THEN ROUND((blks_hit::NUMERIC / (blks_hit + blks_read)::NUMERIC) * 100, 2) ELSE 0 END)::TEXT FROM pg_stat_database WHERE datname != 'template0' ORDER BY datname;"