Prefer more idiomatic approach; avoid use of recuse

Author: phumpal

bin/check-postgres-replication.rb

@@ -117,13 +117,13 @@ def run
                              sslmode: ssl_mode,
                              connect_timeout: config[:timeout])
 
-    begin
-      # PostgreSQL 10
-      master = conn_master.exec('SELECT pg_current_wal_lsn()').getvalue(0, 0)
-    rescue
-      # PostgreSQL <= 9.6
-      master = conn_master.exec('SELECT pg_current_xlog_location()').getvalue(0, 0)
-    end
+    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
+        conn_master.exec('SELECT pg_current_xlog_location()').getvalue(0, 0)
+      end
     m_segbytes = conn_master.exec('SHOW wal_segment_size').getvalue(0, 0).sub(/\D+/, '').to_i << 20
     conn_master.close
 
@@ -136,13 +136,12 @@ def run
                             sslmode: ssl_mode,
                             connect_timeout: config[:timeout])
 
-    begin
-      # PostgreSQL 10
-      slave = conn_slave.exec('SELECT pg_last_wal_replay_lsn()').getvalue(0, 0)
-    rescue
-      # PostgreSQL <= 9.6
-      slave = conn_slave.exec('SELECT pg_last_xlog_receive_location()').getvalue(0, 0)
-    end
+    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
+        conn_slave.exec('SELECT pg_last_xlog_receive_location()').getvalue(0, 0)
+      end
     conn_slave.close
 
     # Computing lag