[pgpool-general: 392] kind mismatch among backends with load balance off

Aleksej Trofimov aleksej.trofimov at ruptela.lt
Thu Apr 26 19:17:50 JST 2012

     I have faced with a problem running pgpool-II version 3.1 and two 
postgresql servers 9.1.2 running streaming replication with hot standby.
     Pgpool configuration:
     backend_weight0 = 1
     backend_weight1 = 0
     load_balance_mode = off
     replication_mode = off
     master_slave_mode = on
     master_slave_sub_mode = 'stream'

     Postgres specific configuration:
     max_standby_archive_delay = 1200s
     max_standby_streaming_delay = 1200s
     (this parameters were configured because of long running queries)

     Our backend 1 server works only for HA and night backup process. We 
are making backup of standby server every night using 2 steps rsync, 
first step with running db, second step disconnects database from pgpool 
(with pcp_detach), stops database, runs second rsync, starts db and 
attaches it (after 1440s timeout) to pgpool. What is specific in this 
configuration is, that second stage rsync needs about 4 hours to 
complete, this why after database startup difference between master and 
standby is about 2 GB (using our network speed we had calculated that we 
need about 1440s of timeout after db startup until connecting it to 
      After all processes are done, database is connected to pool. But 
on pgpool we are getting errors like:

  2012-04-26 12:10:40 ERROR: pid 29814: read_kind_from_backend: 1 th 
kind D does not match with master or majority connection kind C
2012-04-26 12:10:40 ERROR: pid 29814: kind mismatch among backends. 
Possible last query was: "SET LOCAL TIMEZONE TO 
                 FROM data WHERE datetime between 2012-04-25 00:00:00' 
AT TIME ZONE 'GMT' and '2012-04-26 23:59:59' AT TIME ZONE 'GMT'" kind 
details are: 0[C] 1[D];

The strangest think is, that after some time (2 or maybe 3 hours) 
exactly the same query is running good without any problems.. Also how 
could be "kind mismatch error" when load balance is off?

What could be the problem? Maybe postgres configuration issue? Or 
something else? What additiona information could I provide to solve this 

Best regards

Aleksej Trofimov

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