[pgpool-general: 1522] After failover to a newly promoted master, pgpools sends COMMIT to slave causing error
Ron Phipps
ron at endpoint.com
Fri Mar 22 09:20:59 JST 2013
We have the following setup:
1 master
1 slave
Pgpool is not in replication or load balance mode
Test C# application connecting via npgsql or ODBC to both pgpool and
directly to each database
There is a pgpool on each node.
On a newly created cluster with node 0 being the master the test
application works, the query is only sent to the master and we get the
result as expected.
We then shutdown the master on node 0. Repmgr picks up and the slave is
promoted to be the master on node 1. We then bring back up node 0 as a
slave and restart pgpool.
Now when we run the test application the queries run, however we receive
an exception in our code and the error in the logs shows that the COMMIT
in the transaction is being sent to both the new master and the slave,
and the slave returns an error because the BEGIN for a transaction was
never sent to the slave.
The error in the pgpool log is:
Mar 21 23:15:23 centos62 pgpool[1380]: DB node id: 1 backend pid: 3455
statement: BEGIN; SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
Mar 21 23:15:23 centos62 pgpool[1380]: DB node id: 1 backend pid: 3455
statement: select * from GetEventLogTableNames()
Mar 21 23:15:24 centos62 pgpool[1380]: DB node id: 1 backend pid: 3455
statement: fetch all from "<unnamed portal 1>";;
Mar 21 23:15:24 centos62 pgpool[1380]: DB node id: 1 backend pid: 3455
statement: COMMIT
Mar 21 23:15:24 centos62 pgpool[1380]: DB node id: 0 backend pid: 25526
statement: COMMIT
Mar 21 23:15:24 centos62 pgpool[1380]: pool_send_and_wait: Error or
notice message from backend: : DB node id: 0 backend pid: 25526
statement: COMMIT message: there is no transaction in progress
Mar 21 23:15:24 centos62 pgpool[1380]: read_kind_from_backend: 1 th kind
C does not match with master or majority connection kind N
Mar 21 23:15:24 centos62 pgpool[1380]: kind mismatch among backends.
Possible last query was: "COMMIT" kind details are: 0[N: there is no
transaction in progress] 1[C]
Mar 21 23:15:24 centos62 pgpool[1380]: do_child: exits with status 1 due
to error
Now if we bring down node 1, node 0 becomes the new master. We bring
node 1 back up as a slave and do not restart pgpool. We receive the
same error and the commit is sent to both the master and the slave. If
we restart pgpool then things work again.
The key here is it seems that we cannot run this query when node 1 is
the master. I've been working on this issue for the better part of 20
hours now and searched for relevant topics. I found this one in the
archives:
http://www.sraoss.jp/pipermail/pgpool-hackers/2012-July/000095.html
This is the same thing we are seeing where the issue only shows itself
when the master is node 1.
Some additional information, if we have node 1 become the new master and
leave node 0 down, the code works properly because there are no other
backends to send the commits too.
If we test using psql connected to pgpool then in all situations the
following code "works":
OnlineData2=# begin;
BEGIN
OnlineData2=# select * from geteventlogtablenames();
geteventlogtablenames
-----------------------
<unnamed portal 1>
(1 row)
OnlineData2=# commit;
COMMIT
The only problem is that when we watch the pgpool logs we see the following:
Mar 21 23:50:55 centos62 pgpool[6313]: DB node id: 0 backend pid: 6587
statement: begin;
Mar 21 23:50:55 centos62 pgpool[6313]: DB node id: 1 backend pid: 16174
statement: begin;
Mar 21 23:51:04 centos62 pgpool[6313]: DB node id: 1 backend pid: 16174
statement: select * from geteventlogtablenames();
Mar 21 23:51:07 centos62 pgpool[6313]: DB node id: 1 backend pid: 16174
statement: commit;
Mar 21 23:51:07 centos62 pgpool[6313]: DB node id: 0 backend pid: 6587
statement: commit;
Notice how the begin and commit get sent to all nodes, and the select is
only sent to the current master. Why are begin and commit sent to the
other nodes? This seems like part of the problem when we use our app,
the begin and select are sent to the master, but the commit is sent to
all nodes.
Attached is our 2 pgpool configs for node 0 and node 1.
We are committed to finding a fix to this issue and can provide any
applications or access to help track down the problem. I will work on a
non windows application to show the issue if that is needed.
The relevant code for the app is:
OdbcConnection cn;
OdbcCommand cmd;
OdbcDataReader dr;
OdbcTransaction tr = null;
cn = new OdbcConnection("dsn=" + dsn);
cmd = new OdbcCommand("{call GetEventLogTableNames
()}", cn);
cn.Open();
tr = cn.BeginTransaction();
cmd.Transaction = tr;
dr = cmd.ExecuteReader();
while (dr.Read())
{
MessageBox.Show(dr.GetString(0));
}
tr.Commit();
cn.Close();
Thanks,
-Ron
-------------- next part --------------
# ----------------------------
# pgPool-II configuration file
# ----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# Whitespace may be used. Comments are introduced with "#" anywhere on a line.
# The complete list of parameter names and allowed values can be found in the
# pgPool-II documentation.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal. If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, or use "pgpool reload". Some
# parameters, which are marked below, require a server shutdown and restart to
# take effect.
#
#------------------------------------------------------------------------------
# CONNECTIONS
#------------------------------------------------------------------------------
# - pgpool Connection Settings -
listen_addresses = '*'
# Host name or IP address to listen on:
# '*' for all, '' for no TCP/IP connections
# (change requires restart)
port = 5432
# Port number
# (change requires restart)
socket_dir = '/tmp'
# Unix domain socket path
# The Debian package defaults to
# /var/run/postgresql
# (change requires restart)
# - pgpool Communication Manager Connection Settings -
pcp_port = 9898
# Port number for pcp
# (change requires restart)
pcp_socket_dir = '/tmp'
# Unix domain socket path for pcp
# The Debian package defaults to
# /var/run/postgresql
# (change requires restart)
# - Backend Connection Settings -
backend_hostname0 = 'a.b.c.0'
# Host name or IP address to connect to for backend 0
backend_port0 = 5433
# Port number for backend 0
backend_weight0 = 1
# Weight for backend 0 (only in load balancing mode)
backend_data_directory0 = '/var/lib/pgsql/9.1/data'
# Data directory for backend 0
backend_flag0 = 'ALLOW_TO_FAILOVER'
# Controls various backend behavior
# ALLOW_TO_FAILOVER or DISALLOW_TO_FAILOVER
backend_hostname1 = 'a.b.c.1'
backend_port1 = 5433
backend_weight1 = 1
backend_data_directory1 = '/var/lib/pgsql/9.1/data'
backend_flag1 = 'ALLOW_TO_FAILOVER'
# - Authentication -
enable_pool_hba = on
# Use pool_hba.conf for client authentication
authentication_timeout = 60
# Delay in seconds to complete client authentication
# 0 means no timeout.
# - SSL Connections -
ssl = on
# Enable SSL support
# (change requires restart)
ssl_key = '/etc/pgpool-II-91/server.key'
# Path to the SSL private key file
# (change requires restart)
ssl_cert = '/etc/pgpool-II-91/server.crt'
# Path to the SSL public certificate file
# (change requires restart)
#ssl_ca_cert = ''
# Path to a single PEM format file
# containing CA root certificate(s)
# (change requires restart)
#ssl_ca_cert_dir = ''
# Directory containing CA root certificate(s)
# (change requires restart)
#------------------------------------------------------------------------------
# POOLS
#------------------------------------------------------------------------------
# - Pool size -
num_init_children = 32
# Number of pools
# (change requires restart)
max_pool = 4
# Number of connections per pool
# (change requires restart)
# - Life time -
child_life_time = 300
# Pool exits after being idle for this many seconds
child_max_connections = 0
# Pool exits after receiving that many connections
# 0 means no exit
connection_life_time = 0
# Connection to backend closes after being idle for this many seconds
# 0 means no close
client_idle_limit = 0
# Client is disconnected after being idle for that many seconds
# (even inside an explicit transactions!)
# 0 means no disconnection
#------------------------------------------------------------------------------
# LOGS
#------------------------------------------------------------------------------
# - Where to log -
log_destination = 'syslog'
# Where to log
# Valid values are combinations of stderr,
# and syslog. Default to stderr.
# - What to log -
print_timestamp = on
# Print timestamp on each line
# (change requires restart)
log_connections = off
# Log connections
log_hostname = off
# Hostname will be shown in ps status
# and in logs if connections are logged
log_statement = off
# Log all statements
log_per_node_statement = on
# Log all statements
# with node and backend informations
log_standby_delay = 'if_over_threshold'
# Log standby delay
# Valid values are combinations of always,
# if_over_threshold, none
# - Syslog specific -
syslog_facility = 'LOCAL0'
# Syslog local facility. Default to LOCAL0
syslog_ident = 'pgpool'
# Syslog program identification string
# Default to 'pgpool'
# - Debug -
debug_level = 5
# Debug message verbosity level
# 0 means no message, 1 or more mean verbose
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
pid_file_name = '/var/run/pgpool-II-91/pgpool.pid'
# PID file name
# (change requires restart)
logdir = '/tmp'
# Directory of pgPool status file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTION POOLING
#------------------------------------------------------------------------------
connection_cache = on
# Activate connection pools
# (change requires restart)
# Semicolon separated list of queries
# to be issued at the end of a session
# The default is for 8.3 and later
reset_query_list = 'ABORT; DISCARD ALL'
# The following one is for 8.2 and before
#reset_query_list = 'ABORT; RESET ALL; SET SESSION AUTHORIZATION DEFAULT'
#------------------------------------------------------------------------------
# REPLICATION MODE
#------------------------------------------------------------------------------
replication_mode = off
# Activate replication mode
# (change requires restart)
replicate_select = off
# Replicate SELECT statements
# when in replication or parallel mode
# replicate_select is higher priority than
# load_balance_mode.
insert_lock = off
# Automatically locks a dummy row or a table
# with INSERT statements to keep SERIAL data
# consistency
# Without SERIAL, no lock will be issued
lobj_lock_table = ''
# When rewriting lo_creat command in
# replication mode, specify table name to
# lock
# - Degenerate handling -
replication_stop_on_mismatch = off
# On disagreement with the packet kind
# sent from backend, degenerate the node
# which is most likely "minority"
# If off, just force to exit this session
failover_if_affected_tuples_mismatch = off
# On disagreement with the number of affected
# tuples in UPDATE/DELETE queries, then
# degenerate the node which is most likely
# "minority".
# If off, just abort the transaction to
# keep the consistency
#------------------------------------------------------------------------------
# LOAD BALANCING MODE
#------------------------------------------------------------------------------
load_balance_mode = off
# Activate load balancing mode
# (change requires restart)
ignore_leading_white_space = on
# Ignore leading white spaces of each query
white_function_list = ''
# Comma separated list of function names
# that don't write to database
# Regexp are accepted
black_function_list = 'currval,lastval,nextval,setval,%'
# Comma separated list of function names
# that write to database
# Regexp are accepted
#------------------------------------------------------------------------------
# MASTER/SLAVE MODE
#------------------------------------------------------------------------------
master_slave_mode = on
# Activate master/slave mode
# (change requires restart)
master_slave_sub_mode = 'stream'
# Master/slave sub mode
# Valid values are combinations slony or
# stream. Default is slony.
# (change requires restart)
# - Streaming -
sr_check_period = 10
# Streaming replication check period
# Disabled (0) by default
sr_check_user = 'replica'
# Streaming replication check user
# This is neccessary even if you disable streaming
# replication delay check by sr_check_period = 0
sr_check_password = 'xxxx'
# Password for streaming replication check user
delay_threshold = 10000000
# Threshold before not dispatching query to standby node
# Unit is in bytes
# Disabled (0) by default
# - Special commands -
follow_master_command = ''
# Executes this command after master failover
# Special values:
# %d = node id
# %h = host name
# %p = port number
# %D = database cluster path
# %m = new master node id
# %H = hostname of the new master node
# %M = old master node id
# %P = old primary node id
# %% = '%' character
#------------------------------------------------------------------------------
# PARALLEL MODE AND QUERY CACHE
#------------------------------------------------------------------------------
parallel_mode = off
# Activates parallel query mode
# (change requires restart)
enable_query_cache = off
# Activates query cache
# (change requires restart)
pgpool2_hostname = ''
# Set pgpool2 hostname
# (change requires restart)
# - System DB info -
system_db_hostname = 'localhost'
# (change requires restart)
system_db_port = 5432
# (change requires restart)
system_db_dbname = 'pgpool'
# (change requires restart)
system_db_schema = 'pgpool_catalog'
# (change requires restart)
system_db_user = 'pgpool'
# (change requires restart)
system_db_password = ''
# (change requires restart)
#------------------------------------------------------------------------------
# HEALTH CHECK
#------------------------------------------------------------------------------
health_check_period = 0
# Health check period
# Disabled (0) by default
health_check_timeout = 20
# Health check timeout
# 0 means no timeout
health_check_user = 'nobody'
# Health check user
health_check_password = ''
# This parameter is not yet implemented.
# Password for health check user
#------------------------------------------------------------------------------
# FAILOVER AND FAILBACK
#------------------------------------------------------------------------------
failover_command = ''
# Executes this command at failover
# Special values:
# %d = node id
# %h = host name
# %p = port number
# %D = database cluster path
# %m = new master node id
# %H = hostname of the new master node
# %M = old master node id
# %P = old primary node id
# %% = '%' character
failback_command = ''
# Executes this command at failback.
# Special values:
# %d = node id
# %h = host name
# %p = port number
# %D = database cluster path
# %m = new master node id
# %H = hostname of the new master node
# %M = old master node id
# %P = old primary node id
# %% = '%' character
fail_over_on_backend_error = on
# Initiates failover when writing to the
# backend communication socket fails
# This is the same behaviour of pgpool-II
# 2.2.x and previous releases
# If set to off, pgpool will report an
# error and disconnect the session.
#------------------------------------------------------------------------------
# ONLINE RECOVERY
#------------------------------------------------------------------------------
recovery_user = 'nobody'
# Online recovery user
recovery_password = ''
# Online recovery password
recovery_1st_stage_command = ''
# Executes a command in first stage
recovery_2nd_stage_command = ''
# Executes a command in second stage
recovery_timeout = 90
# Timeout in seconds to wait for the
# recovering node's postmaster to start up
# 0 means no wait
client_idle_limit_in_recovery = 0
# Client is disconnected after being idle
# for that many seconds in the second stage
# of online recovery
# 0 means no disconnection
# -1 means immediate disconnection
#------------------------------------------------------------------------------
# OTHERS
#------------------------------------------------------------------------------
relcache_expire = 0
# Life time of relation cache in seconds.
# 0 means no cache expiration(the default).
# The relation cache is used for cache the
# query result against PostgreSQL system
# catalog to obtain various information
# including table structures or if it's a
# temporary table or not. The cache is
# maintained in a pgpool child local memory
# and being kept as long as it survives.
# If someone modify the table by using
# ALTER TABLE or some such, the relcache is
# not consistent anymore.
# For this purpose, cache_expiration
# controls the life time of the cache.
-------------- next part --------------
# ----------------------------
# pgPool-II configuration file
# ----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# Whitespace may be used. Comments are introduced with "#" anywhere on a line.
# The complete list of parameter names and allowed values can be found in the
# pgPool-II documentation.
#
# This file is read on server startup and when the server receives a SIGHUP
# signal. If you edit the file on a running system, you have to SIGHUP the
# server for the changes to take effect, or use "pgpool reload". Some
# parameters, which are marked below, require a server shutdown and restart to
# take effect.
#
#------------------------------------------------------------------------------
# CONNECTIONS
#------------------------------------------------------------------------------
# - pgpool Connection Settings -
listen_addresses = '*'
# Host name or IP address to listen on:
# '*' for all, '' for no TCP/IP connections
# (change requires restart)
port = 5432
# Port number
# (change requires restart)
socket_dir = '/tmp'
# Unix domain socket path
# The Debian package defaults to
# /var/run/postgresql
# (change requires restart)
# - pgpool Communication Manager Connection Settings -
pcp_port = 9898
# Port number for pcp
# (change requires restart)
pcp_socket_dir = '/tmp'
# Unix domain socket path for pcp
# The Debian package defaults to
# /var/run/postgresql
# (change requires restart)
# - Backend Connection Settings -
backend_hostname0 = 'a.b.c.0'
# Host name or IP address to connect to for backend 0
backend_port0 = 5433
# Port number for backend 0
backend_weight0 = 1
# Weight for backend 0 (only in load balancing mode)
backend_data_directory0 = '/var/lib/pgsql/9.1/data'
# Data directory for backend 0
backend_flag0 = 'ALLOW_TO_FAILOVER'
# Controls various backend behavior
# ALLOW_TO_FAILOVER or DISALLOW_TO_FAILOVER
backend_hostname1 = 'a.b.c.1'
backend_port1 = 5433
backend_weight1 = 1
backend_data_directory1 = '/var/lib/pgsql/9.1/data'
backend_flag1 = 'ALLOW_TO_FAILOVER'
# - Authentication -
enable_pool_hba = on
# Use pool_hba.conf for client authentication
authentication_timeout = 60
# Delay in seconds to complete client authentication
# 0 means no timeout.
# - SSL Connections -
ssl = on
# Enable SSL support
# (change requires restart)
ssl_key = '/etc/pgpool-II-91/server.key'
# Path to the SSL private key file
# (change requires restart)
ssl_cert = '/etc/pgpool-II-91/server.crt'
# Path to the SSL public certificate file
# (change requires restart)
#ssl_ca_cert = ''
# Path to a single PEM format file
# containing CA root certificate(s)
# (change requires restart)
#ssl_ca_cert_dir = ''
# Directory containing CA root certificate(s)
# (change requires restart)
#------------------------------------------------------------------------------
# POOLS
#------------------------------------------------------------------------------
# - Pool size -
num_init_children = 32
# Number of pools
# (change requires restart)
max_pool = 4
# Number of connections per pool
# (change requires restart)
# - Life time -
child_life_time = 300
# Pool exits after being idle for this many seconds
child_max_connections = 0
# Pool exits after receiving that many connections
# 0 means no exit
connection_life_time = 0
# Connection to backend closes after being idle for this many seconds
# 0 means no close
client_idle_limit = 0
# Client is disconnected after being idle for that many seconds
# (even inside an explicit transactions!)
# 0 means no disconnection
#------------------------------------------------------------------------------
# LOGS
#------------------------------------------------------------------------------
# - Where to log -
log_destination = 'syslog'
# Where to log
# Valid values are combinations of stderr,
# and syslog. Default to stderr.
# - What to log -
print_timestamp = on
# Print timestamp on each line
# (change requires restart)
log_connections = off
# Log connections
log_hostname = off
# Hostname will be shown in ps status
# and in logs if connections are logged
log_statement = off
# Log all statements
log_per_node_statement = on
# Log all statements
# with node and backend informations
log_standby_delay = 'if_over_threshold'
# Log standby delay
# Valid values are combinations of always,
# if_over_threshold, none
# - Syslog specific -
syslog_facility = 'LOCAL0'
# Syslog local facility. Default to LOCAL0
syslog_ident = 'pgpool'
# Syslog program identification string
# Default to 'pgpool'
# - Debug -
debug_level = 5
# Debug message verbosity level
# 0 means no message, 1 or more mean verbose
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
pid_file_name = '/var/run/pgpool-II-91/pgpool.pid'
# PID file name
# (change requires restart)
logdir = '/tmp'
# Directory of pgPool status file
# (change requires restart)
#------------------------------------------------------------------------------
# CONNECTION POOLING
#------------------------------------------------------------------------------
connection_cache = on
# Activate connection pools
# (change requires restart)
# Semicolon separated list of queries
# to be issued at the end of a session
# The default is for 8.3 and later
reset_query_list = 'ABORT; DISCARD ALL'
# The following one is for 8.2 and before
#reset_query_list = 'ABORT; RESET ALL; SET SESSION AUTHORIZATION DEFAULT'
#------------------------------------------------------------------------------
# REPLICATION MODE
#------------------------------------------------------------------------------
replication_mode = off
# Activate replication mode
# (change requires restart)
replicate_select = off
# Replicate SELECT statements
# when in replication or parallel mode
# replicate_select is higher priority than
# load_balance_mode.
insert_lock = off
# Automatically locks a dummy row or a table
# with INSERT statements to keep SERIAL data
# consistency
# Without SERIAL, no lock will be issued
lobj_lock_table = ''
# When rewriting lo_creat command in
# replication mode, specify table name to
# lock
# - Degenerate handling -
replication_stop_on_mismatch = off
# On disagreement with the packet kind
# sent from backend, degenerate the node
# which is most likely "minority"
# If off, just force to exit this session
failover_if_affected_tuples_mismatch = off
# On disagreement with the number of affected
# tuples in UPDATE/DELETE queries, then
# degenerate the node which is most likely
# "minority".
# If off, just abort the transaction to
# keep the consistency
#------------------------------------------------------------------------------
# LOAD BALANCING MODE
#------------------------------------------------------------------------------
load_balance_mode = off
# Activate load balancing mode
# (change requires restart)
ignore_leading_white_space = on
# Ignore leading white spaces of each query
white_function_list = ''
# Comma separated list of function names
# that don't write to database
# Regexp are accepted
black_function_list = 'currval,lastval,nextval,setval,%'
# Comma separated list of function names
# that write to database
# Regexp are accepted
#------------------------------------------------------------------------------
# MASTER/SLAVE MODE
#------------------------------------------------------------------------------
master_slave_mode = on
# Activate master/slave mode
# (change requires restart)
master_slave_sub_mode = 'stream'
# Master/slave sub mode
# Valid values are combinations slony or
# stream. Default is slony.
# (change requires restart)
# - Streaming -
sr_check_period = 10
# Streaming replication check period
# Disabled (0) by default
sr_check_user = 'replica'
# Streaming replication check user
# This is neccessary even if you disable streaming
# replication delay check by sr_check_period = 0
sr_check_password = 'xxxx'
# Password for streaming replication check user
delay_threshold = 10000000
# Threshold before not dispatching query to standby node
# Unit is in bytes
# Disabled (0) by default
# - Special commands -
follow_master_command = ''
# Executes this command after master failover
# Special values:
# %d = node id
# %h = host name
# %p = port number
# %D = database cluster path
# %m = new master node id
# %H = hostname of the new master node
# %M = old master node id
# %P = old primary node id
# %% = '%' character
#------------------------------------------------------------------------------
# PARALLEL MODE AND QUERY CACHE
#------------------------------------------------------------------------------
parallel_mode = off
# Activates parallel query mode
# (change requires restart)
enable_query_cache = off
# Activates query cache
# (change requires restart)
pgpool2_hostname = ''
# Set pgpool2 hostname
# (change requires restart)
# - System DB info -
system_db_hostname = 'localhost'
# (change requires restart)
system_db_port = 5432
# (change requires restart)
system_db_dbname = 'pgpool'
# (change requires restart)
system_db_schema = 'pgpool_catalog'
# (change requires restart)
system_db_user = 'pgpool'
# (change requires restart)
system_db_password = ''
# (change requires restart)
#------------------------------------------------------------------------------
# HEALTH CHECK
#------------------------------------------------------------------------------
health_check_period = 0
# Health check period
# Disabled (0) by default
health_check_timeout = 20
# Health check timeout
# 0 means no timeout
health_check_user = 'nobody'
# Health check user
health_check_password = ''
# This parameter is not yet implemented.
# Password for health check user
#------------------------------------------------------------------------------
# FAILOVER AND FAILBACK
#------------------------------------------------------------------------------
failover_command = ''
# Executes this command at failover
# Special values:
# %d = node id
# %h = host name
# %p = port number
# %D = database cluster path
# %m = new master node id
# %H = hostname of the new master node
# %M = old master node id
# %P = old primary node id
# %% = '%' character
failback_command = ''
# Executes this command at failback.
# Special values:
# %d = node id
# %h = host name
# %p = port number
# %D = database cluster path
# %m = new master node id
# %H = hostname of the new master node
# %M = old master node id
# %P = old primary node id
# %% = '%' character
fail_over_on_backend_error = on
# Initiates failover when writing to the
# backend communication socket fails
# This is the same behaviour of pgpool-II
# 2.2.x and previous releases
# If set to off, pgpool will report an
# error and disconnect the session.
#------------------------------------------------------------------------------
# ONLINE RECOVERY
#------------------------------------------------------------------------------
recovery_user = 'nobody'
# Online recovery user
recovery_password = ''
# Online recovery password
recovery_1st_stage_command = ''
# Executes a command in first stage
recovery_2nd_stage_command = ''
# Executes a command in second stage
recovery_timeout = 90
# Timeout in seconds to wait for the
# recovering node's postmaster to start up
# 0 means no wait
client_idle_limit_in_recovery = 0
# Client is disconnected after being idle
# for that many seconds in the second stage
# of online recovery
# 0 means no disconnection
# -1 means immediate disconnection
#------------------------------------------------------------------------------
# OTHERS
#------------------------------------------------------------------------------
relcache_expire = 0
# Life time of relation cache in seconds.
# 0 means no cache expiration(the default).
# The relation cache is used for cache the
# query result against PostgreSQL system
# catalog to obtain various information
# including table structures or if it's a
# temporary table or not. The cache is
# maintained in a pgpool child local memory
# and being kept as long as it survives.
# If someone modify the table by using
# ALTER TABLE or some such, the relcache is
# not consistent anymore.
# For this purpose, cache_expiration
# controls the life time of the cache.
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