我有一个问题，pgpool II在主从模式下配置，并在slony上进行复制。 我已经在每台服务器上配置了postgres数据库，以便尽可能快地运行，当我直接建立与数据库服务器的连接时，我已经验证了这一点。但是当pgpool建立连接错误时，tomcat上的webapp启动速度非常慢（比较5分钟没有pgpool）。
我无法弄清楚出了什么问题。在工作webapp上，通信速度有点慢，但差异远小于启动时。
PGPool使用ssh隧道与服务器通信。
我已经读过关于pgpool的内容，如果我理解正确，连接数（池）由元组（数据库，用户）决定。我只使用一个数据库和用户，这是一个原因吗？如果有的话，我还能做些什么来加速pgpool？
配置信息： CentOS 6 x64 Postgres 9.2.4 PGPool II 3.2.5
有3台服务器，其中两台是postgres数据库，由slony复制，另一台是pgpool正在运行。
我的pgpool.conf
#------------------------------------------------------------------------------
# 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 = '/var/run'
# 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 = '/var/run'
# - Backend Connection Settings -
backend_hostname0 = '127.0.0.1'
# Host name or IP address to connect to for backend 0
backend_port0 = 27930
# Port number for backend 0
backend_weight0 = 1
# Weight for backend 0 (only in load balancing mode)
backend_data_directory0 = '/usr/local/pgsql/data'
# Data directory for backend 0
backend_flag0 = 'ALLOW_TO_FAILOVER'
# Controls various backend behavior
# ALLOW_TO_FAILOVER or DISALLOW_TO_FAILOVER
backend_hostname1 = '127.0.0.1'
backend_port1 = 27931
backend_weight1 = 1
backend_data_directory1 = '/usr/local/pgsql/data'
backend_flag1 = 'ALLOW_TO_FAILOVER'
# - Authentication -
enable_pool_hba = on
# Use pool_hba.conf for client authentication
pool_passwd = ''
# File name of pool_passwd for md5 authentication.
# "" disables pool_passwd.
# (change requires restart)
authentication_timeout = 30
# Delay in seconds to complete client authentication
# 0 means no timeout.
# - SSL Connections -
ssl = off
# Enable SSL support
# (change requires restart)
ssl_key = './server.key'
# Path to the SSL private key file
# (change requires restart)
ssl_cert = './server.cert'
# Path to the SSL public certificate file
# (change requires restart)
ssl_ca_cert = './root.crt'
# 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 = 512
# Number of pools
# (change requires restart)
max_pool = 2
# 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 = 'stderr'
# 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 = on
# Log connections
log_hostname = on
# Hostname will be shown in ps status
# and in logs if connections are logged
log_statement = on
# Log all statements
log_per_node_statement = on
# Log all statements
# with node and backend informations
log_standby_delay = 'none'
# 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 = 1
# Debug message verbosity level
# 0 means no message, 1 or more mean verbose
#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------
pid_file_name = '/usr/local/etc/pgpool.pid'
# PID file name
# (change requires restart)
logdir = '/usr/local/etc/'
# 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 = on
# 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 = 'slony'
# Master/slave sub mode
# Valid values are combinations slony or
# stream. Default is slony.
# (change requires restart)
# - Streaming -
sr_check_period = 0
# Streaming replication check period
# Disabled (0) by default
sr_check_user = 'nobody'
# Streaming replication check user
# This is neccessary even if you disable streaming
# replication delay check by sr_check_period = 0
sr_check_password = ''
# Password for streaming replication check user
delay_threshold = 0
# 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
# %r = new master port number
# %R = new master database cluster path
# %% = '%' character
#------------------------------------------------------------------------------
# PARALLEL MODE
#------------------------------------------------------------------------------
parallel_mode = off
# Activates parallel query mode
# (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 = 10
# Health check period
# Disabled (0) by default
health_check_timeout = 20
# Health check timeout
# 0 means no timeout
health_check_user = 'postgres'
# Health check user
health_check_password = ''
# Password for health check user
health_check_max_retries = 0
# Maximum number of times to retry a failed health check before giving up.
health_check_retry_delay = 1
# Amount of time to wait (in seconds) between retries.
#------------------------------------------------------------------------------
# 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
# %r = new master port number
# %R = new master database cluster path
# %% = '%' 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
# %r = new master port number
# %R = new master database cluster path
# %% = '%' character
fail_over_on_backend_error = on
# Initiates failover when reading/writing to the
# backend communication socket fails
# 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
#------------------------------------------------------------------------------
# WATCHDOG
#------------------------------------------------------------------------------
use_watchdog = off
# Activates watchdog
# (change requires restart)
trusted_servers = ''
# trusted server list which are used
# to confirm network connection
# (hostA,hostB,hostC,...)
# (change requires restart)
delegate_IP = ''
# delegate IP address
# (change requires restart)
wd_hostname = ''
# Host name or IP address of this watchdog
# (change requires restart)
wd_port = 9000
# port number for watchdog service
# (change requires restart)
wd_interval = 10
# lifecheck interval (sec) > 0
# (change requires restart)
ping_path = '/bin'
# ping command path
# (change requires restart)
ifconfig_path = '/sbin'
# ifconfig command path
# (change requires restart)
if_up_cmd = 'ifconfig eth0:0 inet $_IP_$ netmask 255.255.255.0'
# startup delegate IP command
# (change requires restart)
if_down_cmd = 'ifconfig eth0:0 down'
# shutdown delegate IP command
# (change requires restart)
arping_path = '/usr/sbin' # arping command path
# (change requires restart)
arping_cmd = 'arping -U $_IP_$ -w 1'
# arping command
# (change requires restart)
wd_life_point = 3
# lifecheck retry times
# (change requires restart)
wd_lifecheck_query = 'SELECT 1'
# lifecheck query to pgpool from watchdog
# (change requires restart)
# Other pgpool Connection Settings
#other_pgpool_hostname0 = 'host0'
# Host name or IP address to connect to for other pgpool 0
#other_pgpool_port0 = 5432
# Port number for othet pgpool 0
#other_wd_port0 = 9000
# Port number for othet watchdog 0
#other_pgpool_hostname1 = 'host1'
#other_pgpool_port1 = 5432
#other_wd_port1 = 9000
#------------------------------------------------------------------------------
# OTHERS
#------------------------------------------------------------------------------
relcache_expire = 0
relcache_size = 256
# Number of relation cache
# entry. If you see frequently:
# "pool_search_relcache: cache replacement happend"
# in the pgpool log, you might want to increate this number.
check_temp_table = on
# If on, enable temporary table check in SELECT statements.
# This initiates queries against system catalog of primary/master
# thus increases load of master.
# If you are absolutely sure that your system never uses temporary tables
# and you want to save access to primary/master, you could turn this off.
# Default is on.
#------------------------------------------------------------------------------
# ON MEMORY QUERY MEMORY CACHE
#------------------------------------------------------------------------------
memory_cache_enabled = off
# If on, use the memory cache functionality, off by default
memqcache_method = 'shmem'
# Cache storage method. either 'shmem'(shared memory) or
# 'memcached'. 'shmem' by default
# (change requires restart)
memqcache_memcached_host = 'localhost'
# Memcached host name or IP address. Mandatory if
# memqcache_method = 'memcached'.
# Defaults to localhost.
# (change requires restart)
memqcache_memcached_port = 11211
# Memcached port number. Mondatory if memqcache_method = 'memcached'.
# Defaults to 11211.
# (change requires restart)
memqcache_total_size = 67108864
# Total memory size in bytes for storing memory cache.
# Mandatory if memqcache_method = 'shmem'.
# Defaults to 64MB.
# (change requires restart)
memqcache_max_num_cache = 1000000
# Total number of cache entries. Mandatory
# if memqcache_method = 'shmem'.
# Each cache entry consumes 48 bytes on shared memory.
# Defaults to 1,000,000(45.8MB).
# (change requires restart)
memqcache_expire = 0
# Memory cache entry life time specified in seconds.
# 0 means infinite life time. 0 by default.
# (change requires restart)
memqcache_auto_cache_invalidation = on
# If on, invalidation of query cache is triggered by corresponding
# DDL/DML/DCL(and memqcache_expire). If off, it is only triggered
# by memqcache_expire. on by default.
# (change requires restart)
memqcache_maxcache = 409600
# Maximum SELECT result size in bytes.
# Must be smaller than memqcache_cache_block_size. Defaults to 400KB.
# (change requires restart)
memqcache_cache_block_size = 1048576
# Cache block size in bytes. Mandatory if memqcache_method = 'shmem'.
# Defaults to 1MB.
# (change requires restart)
memqcache_oiddir = '/var/log/pgpool/oiddir'
# Temporary work directory to record table oids
# (change requires restart)
white_memqcache_table_list = ''
# Comma separated list of table names to memcache
# that don't write to database
# Regexp are accepted
black_memqcache_table_list = ''
# Comma separated list of table names not to memcache
# that don't write to database
# Regexp are accepted
提前致谢。