Class: NewRelic::PostgresPlugin::Agent

Inherits:
NewRelic::Plugin::Agent::Base
  • Object
show all
Defined in:
lib/newrelic_postgres_plugin/agent.rb

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Agent 



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 20

def initialize(*args)
  @previous_metrics = {}
  @previous_result_for_query ||= {}
  super
end

Instance Method Details

#connect ⇒ Object

Get a connection to postgres



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 42

def connect
  PG::Connection.new(:host => host, :port => port, :user => user, :password => password, :sslmode => sslmode, :dbname => dbname)
end

#nine_two? ⇒ Boolean

Returns true if we’re talking to Postgres version >= 9.2



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 49

def nine_two?
  @connection.server_version >= 90200
end

#poll_cycle ⇒ Object

This is called on every polling cycle



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 56

def poll_cycle
  @connection = self.connect

  report_metrics

rescue => e
  $stderr.puts "#{e}: #{e.backtrace.join("\n  ")}"
ensure
  @connection.finish if @connection
end

#port ⇒ Object

You do not have to specify the postgres port in the yaml if you don’t want to.



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 35

def port
  @port || 5432
end

#report_metrics ⇒ Object 



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 67

def report_metrics
  @connection.exec(backend_query) do |result|
    report_metric "Backends/Active", 'connections', result[0]['backends_active']
    report_metric "Backends/Idle",   'connections', result[0]['backends_idle']
  end
  @connection.exec(database_query) do |result|
    result.each do |row|
      report_metric         "Database/Backends",                 '', row['numbackends'].to_i
      report_derived_metric "Database/Transactions/Committed",   'transactions', row['xact_commit'].to_i
      report_derived_metric "Database/Transactions/Rolled Back", 'transactions', row['xact_rollback'].to_i

      report_derived_metric "Database/Rows/Selected", 'rows', row['tup_returned'].to_i + row['tup_fetched'].to_i
      report_derived_metric "Database/Rows/Inserted", 'rows', row['tup_inserted'].to_i
      report_derived_metric "Database/Rows/Updated",  'rows', row['tup_updated'].to_i
      report_derived_metric "Database/Rows/Deleted",  'rows', row['tup_deleted'].to_i

    end
  end
  @connection.exec(index_count_query) do |result|
    report_metric "Database/Indexes/Count", 'indexes', result[0]['indexes'].to_i
  end
  @connection.exec(index_size_query) do |result|
    report_metric "Database/Indexes/Size", 'bytes', result[0]['size'].to_i
  end
  @connection.exec(bgwriter_query) do |result|
    report_derived_metric "Background Writer/Checkpoints/Scheduled", 'checkpoints', result[0]['checkpoints_timed'].to_i
    report_derived_metric "Background Writer/Checkpoints/Requested", 'checkpoints', result[0]['checkpoints_requests'].to_i
  end
  report_metric "Alerts/Index Miss Ratio", '%', calculate_miss_ratio(%Q{SELECT SUM(idx_blks_hit) AS hits, SUM(idx_blks_read) AS reads FROM pg_statio_user_indexes})
  report_metric "Alerts/Cache Miss Ratio", '%', calculate_miss_ratio(%Q{SELECT SUM(heap_blks_hit) AS hits, SUM(heap_blks_read) AS reads FROM pg_statio_user_tables})

  # This is dependent on the pg_stat_statements being loaded, and assumes that pg_stat_statements.max has been set sufficiently high that most queries will be recorded. If your application typically generates more than 1000 distinct query plans per sampling interval, you're going to have a bad time.
  if extension_loaded? "pg_stat_statements"
    @connection.exec("SELECT SUM(calls) FROM pg_stat_statements") do |result|
      report_derived_metric "Database/Statements", '', result[0]["sum"].to_i
    end
  else
    puts "pg_stat_statements is not loaded; no Database/Statements metric will be reported."
  end
end

#setup_metrics ⇒ Object

Required, but not used



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# File 'lib/newrelic_postgres_plugin/agent.rb', line 29

def setup_metrics
end