[Pgpool-general] thousands of queries from pgpool to one of the backends (queries I don't do)

[Tomasz Chmielewski]

I have pgpool configured to write to two backends and read from one backend:


# 1st backend
backend_hostname0 = '192.168.15.101'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = '/var/lib/postgresql/8.3/main'


# 2nd backend - we only write to it (it has weight 0); unless the local one crashed
backend_hostname1 = '192.168.15.201'
backend_port1 = 5432
backend_weight1 = 0
backend_data_directory1 = '/var/lib/postgresql/8.3/main'



Both PostgreSQL servers use the same configuration (identical postgresql.conf files).


However, as I test it and analyze the logs, I see backend0 gets around 30 queries per hour (which is more or less the number of queries I do).

On the other hand, backend1 gets literally _tens of thousands_ of queries from pgpool, and it's not anything I ask the server. They look like below:

[383-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.055 ms  statement: SHOW client_encoding
[384-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.050 ms  statement: SHOW default_transaction_isolation
[385-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.043 ms  statement: BEGIN; SET TRANSACTION ISOLATION LEVEL READ COMMITTED
[386-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.034 ms  statement: SET TIME ZONE E'Asia/Singapore'
[387-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.035 ms  statement: ROLLBACK
[388-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.023 ms  statement: BEGIN
[389-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.032 ms  statement:  RESET ALL
[390-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.026 ms  statement: COMMIT
[391-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.024 ms  statement: BEGIN
[392-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.036 ms  statement:  SET SESSION AUTHORIZATION DEFAULT
[393-1] 2010-03-01 03:06:56 SGT LOG:  duration: 0.028 ms  statement: COMMIT


And they are repeated every second or so.

Does anyone have an idea why pgpool queries one of the backends so often?
The queries I made by pgpool, as they stop when I stop pgpool.

I use pgpool-2.3.2.2, but I had this also with pgpool 2.3.1.


-- 
Tomasz Chmielewski
http://wpkg.org