/[munin-modules]/postgres_block_read_
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Annotation of /postgres_block_read_

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Revision 1 - (hide annotations)
Tue Jun 12 11:02:00 2007 UTC (15 years, 5 months ago) by dpavlin
File size: 5432 byte(s)
import munin PostgreSQL modules from Bjorn Ruberg

1 dpavlin 1 #!/usr/bin/perl
2    
3     # Plugin to monitor Postgresql memory usage; gives number of blocks
4     # read from disk and from memory, showing how much of the database is
5     # served from Postgresql's memory buffer.
6     #
7     # PLEASE NOTE: This plugin may not present the whole truth - the truth
8     # may actually be even better than this plugin will show you! That is
9     # because Postgresql statistics only considers memory block reads from
10     # its own allocated memory. When Postgresql reads from disk, it may
11     # actually still be read from memory, but from the _kernel_'s
12     # memory. Summarily, your database server may run even better than
13     # this plugin will indicate. See
14     # http://www.postgresql.org/docs/7.4/interactive/monitoring-stats.html
15     # for a (short) description.
16     #
17     # Copyright Bjørn Ruberg <bjorn@linpro.no> 2006
18     #
19     # Licenced under GPL v2.
20     #
21     # Usage:
22     #
23     # Symlink into /etc/munin/plugins/ and add the monitored
24     # database to the filename. e.g.:
25     #
26     # ln -s /usr/share/munin/plugins/postgres_block_read_ \
27     # /etc/munin/plugins/postgres_block_read_SomeDatabase
28     # This should, however, be given through autoconf and suggest.
29     #
30     # If required, give username, password and/or Postgresql server
31     # host through environment variables.
32     #
33     # You must also activate Postgresql statistics. See
34     # http://www.postgresql.org/docs/7.4/interactive/monitoring-stats.html
35     # for how to enable this. Specifically, the following lines must
36     # exist in your postgresql.conf:
37     #
38     # stats_start_collector = true
39     # stats_block_level = true
40     #
41     #
42     # Parameters:
43     #
44     # config (required)
45     #
46     # Config variables:
47     #
48     # dbhost - Which database server to use. Defaults to
49     # 'localhost'.
50     # dbuser - A Postgresql user account with read permission to
51     # the given database. Defaults to
52     # 'postgres'. Anyway, Munin must be told which user
53     # this plugin should be run as.
54     # dbpass - The corresponding password, if
55     # applicable. Default to undef. Remember that
56     # pg_hba.conf must be configured accordingly.
57     #
58     # Magic markers
59     #%# family=auto
60     #%# capabilities=autoconf suggest
61    
62     use strict;
63     use DBI;
64     use Data::Dumper;
65     use vars qw ( $debug $suggest $configure $dbh );
66    
67     # Need these variables at an early stage to enable
68     # autoconf and suggest
69     my $dbhost = $ENV{'dbhost'} || ''; # Connect to localhost by default
70     my $dbname = $ENV{'dbname'} || 'template1';
71     my $dbuser = $ENV{'dbuser'} || 'postgres';
72     my $dbpass = $ENV{'dbpass'} || '';
73    
74     if (exists $ARGV[0]) {
75     if ($ARGV[0] eq 'autoconf') {
76     # Check for DBD::Pg
77     if (! eval "require DBD::Pg;") {
78     print "no (DBD::Pg not found)";
79     exit 1;
80     }
81     # Then we try to detect Postgres presence by connecting to
82     # 'template1'.
83     my $dsn = "dbi:Pg:dbname=template1";
84     $dsn .= ";host=$dbhost" if $dbhost;
85     my $tempdbh = DBI->connect ($dsn, $dbuser, $dbpass);
86     if ($tempdbh) {
87     print "yes\n";
88     exit 0;
89     } else {
90     print "no (Can't connect to given host, please check environment settings)\n";
91     exit 1;
92     }
93     } elsif ($ARGV[0] eq 'debug') {
94     # Set debug flag
95     $debug = 1;
96     } elsif ($ARGV[0] eq 'config') {
97     # Set config flag
98     $configure = 1;
99     } elsif ($ARGV[0] eq 'suggest') {
100     # doesn't always work
101     my @datasources = DBI->data_sources ('Pg');
102     foreach my $dsn (grep !/\=template\d$/, @datasources) {
103     (my $db = $dsn) =~ s/^.*=//;
104     print "$db\n";
105     }
106     exit 0;
107     }
108     }
109    
110     # Must do this here, after checking for autoconf/suggest/etc, because the
111     # plugin must be able to run before it is linked to the databases.
112     my (undef, undef, undef, $dbname) = split (/_/, $0, 4);
113     die "No dbname configured (did you make the proper symlink?)" unless $dbname;
114    
115     my @datasources = DBI->data_sources ('Pg')
116     or die ("Can't read any possible data sources: $?");
117    
118     my $dsn = "DBI:Pg:dbname=$dbname";
119     $dsn .= ";host=$dbhost" if $dbhost;
120     print "#$dsn\n" if $debug;
121     my $dbh = DBI->connect ($dsn, $dbuser, $dbpass, {RaiseError =>1});
122     unless($dbh) {
123     die("Database $dbname\@$dbhost (". $DBI::errstr .")\n");
124     }
125    
126     if ($configure) {
127     print <<EOF;
128     graph_title Postgres data reads from $dbname
129     graph_args --base 1000
130     graph_vlabel Blocks read per \${graph_period}
131     graph_category Postgresql
132     graph_info Shows number of blocks read from disk and from memory
133     from_disk.label Read from disk
134     from_disk.info Read from disk
135     from_disk.type DERIVE
136     from_disk.min 0
137     from_disk.draw AREA
138     from_memory.label Cached in memory
139     from_memory.info Cached in memory
140     from_memory.type DERIVE
141     from_memory.min 0
142     from_memory.draw STACK
143     EOF
144     } else {
145     my $sql = "SELECT (SUM (heap_blks_read) + SUM (idx_blks_read) + ";
146     $sql .= "SUM (toast_blks_read) + SUM (tidx_blks_read)) AS disk, ";
147     $sql .= "(SUM (heap_blks_hit) +SUM (idx_blks_hit) + ";
148     $sql .= "SUM (toast_blks_hit) + SUM (tidx_blks_hit)) AS mem ";
149     $sql .= "from pg_statio_user_tables ";
150     print "# $sql\n" if $debug;
151     my $sth = $dbh->prepare ($sql);
152     $sth->execute();
153     if ($sth->rows > 0) {
154     printf ("# Rows: %d\n", $sth->rows) if $debug;
155     my ($disk, $mem) = $sth->fetchrow_array();
156     print "from_disk.value $disk\n";
157     print "from_memory.value $mem\n";
158     }
159     }

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