Adds numbackends to metric-postgres-statsdb

Author: phumpal

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed at [Keep A Changelog](http://keepachangelog.com/)
 
 ## [Unreleased]
+### Added
+- metric-postgres-statsdb.rb: Adds new metric `numbackends`.
 
 ## [1.1.2] - 2017-06-02
 ### Fixed

bin/metric-postgres-statsdb.rb

@@ -83,13 +83,14 @@ def run
                          port: config[:port],
                          connect_timeout: config[:timeout])
     request = [
-      'select xact_commit, xact_rollback,',
+      'select numbackends, xact_commit, xact_rollback,',
       'blks_read, blks_hit,',
       'tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted',
       "from pg_stat_database where datname='#{config[:database]}'"
     ]
     con.exec(request.join(' ')) do |result|
       result.each do |row|
+        output "#{config[:scheme]}.statsdb.#{config[:database]}.numbackends", row['numbackends'], timestamp
         output "#{config[:scheme]}.statsdb.#{config[:database]}.xact_commit", row['xact_commit'], timestamp
         output "#{config[:scheme]}.statsdb.#{config[:database]}.xact_rollback", row['xact_rollback'], timestamp
         output "#{config[:scheme]}.statsdb.#{config[:database]}.blks_read", row['blks_read'], timestamp