Collect more DB tuple stats

Closes #12

Gemfile.lock

 PATH
   remote: .
   specs:
-    gitlab-monitor (0.0.22)
+    gitlab-monitor (0.0.25)
       pg (~> 0.18.4)
       quantile (~> 0.2.0)
       redis-namespace (~> 1.5.2)

README.md

@@ -13,7 +13,7 @@ frequency.
 ### Supported Probes
 
 1. Database
-    * Dead tuples
+    * Per-table tuple stats
     * Slow queries
     * Blocked queries
     * Vacuum queries

config/gitlab-monitor.yml.example

@@ -5,8 +5,8 @@ server:
 probes:
   database:
     multiple: true
-    dead_tuples_count:
-      class_name: Database::DeadTuplesProber
+    tuple_stats:
+      class_name: Database::TuplesProber
       methods:
         - probe_db
       opts:

lib/gitlab_monitor/cli.rb

@@ -76,11 +76,11 @@ module GitLab
         end
       end
 
-      # Database dead tuples runner.
+      # Database tuple stats runner.
       #
       # It will take a database connection string and print results to STDOUT
-      class DatabaseDeadTuples
-        COMMAND_NAME = "db-dead-tuples".freeze
+      class DatabaseTupleStats
+        COMMAND_NAME = "db-tuple-stats".freeze
 
         def initialize(args)
           @options = options(args)
@@ -106,7 +106,7 @@ module GitLab
         def run
           validate!
 
-          ::GitLab::Monitor::Database::DeadTuplesProber.new(connection_string: @db_connection_string)
+          ::GitLab::Monitor::Database::TuplesProber.new(connection_string: @db_connection_string)
                                                    .probe_db
                                                    .write_to(@target)
         end
@@ -451,7 +451,7 @@ module GitLab
       def self.commands
         [
           GIT,
-          DatabaseDeadTuples,
+          DatabaseTupleStats,
           DatabaseBlockedQueries,
           DatabaseSlowQueries,
           DatabaseVacuumQueries,

lib/gitlab_monitor/database.rb

@@ -6,7 +6,7 @@ module GitLab
       autoload :BlockedQueriesProber, "gitlab_monitor/database/blocked_queries"
       autoload :CiBuildsProber,       "gitlab_monitor/database/ci_builds"
       autoload :SlowQueriesProber,    "gitlab_monitor/database/slow_queries"
-      autoload :DeadTuplesProber,     "gitlab_monitor/database/dead_tuples"
+      autoload :TuplesProber,         "gitlab_monitor/database/tuple_stats"
       autoload :VacuumQueriesProber,  "gitlab_monitor/database/vacuum_queries"
       autoload :RowCountProber,       "gitlab_monitor/database/row_count"
     end

lib/gitlab_monitor/database/dead_tuples.rb → lib/gitlab_monitor/database/tuple_stats.rb

 module GitLab
   module Monitor
     module Database
-      # A helper class to collect dead tuples stats from the database
+      # A helper class to collect tuple stats from the database
       #
       # It takes a connection string (e.g. "dbname=test port=5432")
-      class DeadTuplesCollector < Base
+      class TupleStatsCollector < Base
         def run
           table_names = connection.exec("SELECT tablename FROM pg_tables WHERE tableowner = 'gitlab'").values.flatten
           stats       = {}
 
           table_names.each do |table_name|
-            result = connection.exec("SELECT n_dead_tup FROM pg_stat_user_tables WHERE relname = '#{table_name}'")
-            stats[table_name] = result[0]["n_dead_tup"].to_i
+            result = connection.exec(
+              <<-SQL
+                SELECT seq_tup_read, idx_tup_fetch, n_tup_ins, n_tup_upd, n_tup_del, n_tup_hot_upd, n_dead_tup
+                FROM pg_stat_user_tables
+                WHERE relname = '#{table_name}'
+              SQL
+            )
+            next if result.count.zero?
+
+            stats[table_name] = result[0]
           end
 
           stats
         end
       end
 
-      # Probes the DB specified by opts[:connection_string] for dead tubles stats, then converts them to metrics
-      class DeadTuplesProber
+      # Probes the DB specified by opts[:connection_string] for tuple stats, then converts them to metrics
+      class TuplesProber
         def initialize(opts, metrics: PrometheusMetrics.new)
           @metrics   = metrics
-          @collector = DeadTuplesCollector.new(connection_string: opts[:connection_string])
+          @collector = TupleStatsCollector.new(connection_string: opts[:connection_string])
         end
 
         def probe_db
@@ -30,8 +38,10 @@ module GitLab
 
           result = @collector.run
 
-          result.each do |table_name, dead_tuples_count|
-            @metrics.add("pg_dead_tuples", dead_tuples_count, table_name: table_name)
+          result.each do |table_name, tuple_stats|
+            tuple_stats.each do |column_name, value|
+              @metrics.add("pg_stat_table_#{column_name}", value.to_s, table_name: table_name)
+            end
           end
 
           self