Adds version function

Author: phumpal

bin/check-postgres-replication.rb

@@ -104,6 +104,11 @@ def compute_lag(master, slave, m_segbytes)
     ((m_segment.hex - s_segment.hex) * m_segbytes) + (m_offset.hex - s_offset.hex)
   end
 
+  def check_vsn(conn)
+    pg_vsn = conn.exec("SELECT current_setting('server_version')").getvalue(0, 0)
+    return if Gem::Version.new(pg_vsn) < Gem::Version.new('10.0') && Gem::Version.new(pg_vsn) >= Gem::Version.new('9.0')
+  end
+
   def run
     ssl_mode = config[:ssl] ? 'require' : 'prefer'
 
@@ -117,12 +122,10 @@ def run
                              sslmode: ssl_mode,
                              connect_timeout: config[:timeout])
 
-    pg_vsn = conn_master.exec("SELECT current_setting('server_version')").getvalue(0, 0)
-
-    master = if Gem::Version.new(pg_vsn) > Gem::Version.new('9.6')
-               conn_master.exec('SELECT pg_current_wal_lsn()').getvalue(0, 0)
-             else
+    master = if check_vsn(conn_master)
                conn_master.exec('SELECT pg_current_xlog_location()').getvalue(0, 0)
+             else
+               conn_master.exec('SELECT pg_current_wal_lsn()').getvalue(0, 0)
              end
     m_segbytes = conn_master.exec('SHOW wal_segment_size').getvalue(0, 0).sub(/\D+/, '').to_i << 20
     conn_master.close
@@ -136,10 +139,10 @@ def run
                             sslmode: ssl_mode,
                             connect_timeout: config[:timeout])
 
-    slave = if Gem::Version.new(pg_vsn) > Gem::Version.new('9.6')
-              conn_slave.exec('SELECT pg_last_wal_replay_lsn()').getvalue(0, 0)
-            else
+    slave = if check_vsn(conn_slave)
               conn_slave.exec('SELECT pg_last_xlog_receive_location()').getvalue(0, 0)
+            else
+              conn_slave.exec('SELECT pg_last_wal_replay_lsn()').getvalue(0, 0)
             end
     conn_slave.close