plugin-pg__database_hitratio: pg__database_hitratio

#!/usr/bin/perl -w
# Plugin for monitor postgres database reads.
#
# Licenced under GPL v2.
#
# Usage:
#
#       Symlink into /etc/munin/plugins/ and add the monitored
#       database to the filename. e.g.:
#
#       ln -s /usr/share/munin/plugins/pg_database__blks \
#         /etc/munin/plugins/pg_database_<databasename>_blks
#       This should, however, be given through autoconf and suggest.
#
#       If required, give username, password and/or Postgresql server
#       host through environment variables.
#
#       You must also activate Postgresql statistics. See
#       http://www.postgresql.org/docs/7.4/interactive/monitoring-stats.html
#       for how to enable this. Specifically, the following lines must
#       exist in your postgresql.conf:
#
#           stats_start_collector = true
#           stats_block_level = true
#
#
# Parameters:
#
#       config   (required)
#
# Config variables:
#
#       dbhost     - Which database server to use. Defaults to
#                    'localhost'.
#       dbname     - Which database to use. Defaults to template1
#       dbuser     - A Postgresql user account with read permission to
#                    the given database. Defaults to
#                    'postgres'. Anyway, Munin must be told which user
#                    this plugin should be run as.
#       dbpass     - The corresponding password, if
#                    applicable. Default to undef. Remember that
#                    pg_hba.conf must be configured accordingly.
#
# Magic markers
#%# family=auto
#%# capabilities=autoconf

use strict;
use DBI;

my $dbhost = $ENV{'dbhost'} || '127.0.0.1';
my $dbname = $ENV{'dbname'} || 'template1';
my $dbuser = $ENV{'dbuser'} || 'postgres';
my $dbport = $ENV{'dbport'} || '5432';
my $dbpass = $ENV{'dbpass'} || '';

# Check for DBD::Pg
if (! eval "require DBD::Pg;") {
     exit 1;
}

my $dsn = "DBI:Pg:dbname=$dbname;host=$dbhost;port=$dbport";
#print "$dsn\n";
my $dbh = DBI->connect ($dsn, $dbuser,
                        $dbpass,
                        {RaiseError =>1}) || die "";



if (exists $ARGV[0]) {
    if ($ARGV[0] eq 'autoconf') {
        # Check for DBD::Pg
        if (! eval "require DBD::Pg;") {
             print "no (DBD::Pg not found)";
             exit 1;
        }
        if ($dbh) {
            print "yes\n";
            exit 0;
        } else {
            print "no Unable to access Database $dbname on host $dbhost as user $dbuser.\nError returned was: ". $DBI::errstr;
            exit 1;
        }
    }

    if ($ARGV[0] eq "config") {
        print "graph_title PostgreSQL database read hitratio from $dbname\n";
        print "graph_args --upper-limit 110 -l 0\n";
        print "graph_vlabel %\n";
        print "graph_category Postgresql\n";
        print "graph_info This graph shows the percentage of blocks read from the cache\n";
        print "read_hitratio.label Cache hitratio\n";
        print "read_hitratio.type GAUGE\n";
        print "read_hitratio.draw LINE2\n";
        exit 0;
    }
}


my $sql_curr = "select blks_read,blks_hit from pg_stat_database where datname='$dbname';";
my $sth_curr = $dbh->prepare($sql_curr);
$sth_curr->execute();
my ($blks_read,$blks_hit) = $sth_curr->fetchrow();
my $read_hitratio =  ($blks_hit/($blks_read+$blks_hit))*100;
print "read_hitratio.value $read_hitratio\n";