[pgpool-general-jp: 931] PostgreSQL9.0(SR環境）でload_balance_mode = true時のINSERT後のSELECT currvalでマスタ側のシーケンスを取得しないことがある

[山下大介]

初めまして。
サイバースターの山下と申します。

題記の件ですが、現在、PostgreSQL9.0.1 SR（3台） + pgpool-II 3.0.3でSELECTのバランシングを
行おうと思っているのですが、INSERT後のSELECT curvalでどうもスレーブに処理が流れてしまうことがあります。

何か、設定に問題がある等、ご教授頂けないでしょうか？
その他、ログ等が必要でしたら、対応しますので、ご指示頂ければと思います。

black_function_list = 'nextval,setval,currval,lastval'　や insert
lock等も有効にしたりといろいろと思考錯誤はしたのですが、
解決しないため、何卒宜しくお願い致します。

◆発生頻度
30%程度(約3回に一回程度発生）

◆INSERT実行後に実行しているSQL
SELECT currval('step_id_seq') AS step_id;

◆エラーメッセージ
Warning: pg_exec() [function.pg-exec]: Query failed: ERROR: currval of
sequence "step_id_seq" is not yet defined in this session in
/home/public_html/test.php on line xxx

◆環境
※その他環境でも現象は確認しており、環境依存でないことは確認しております。

■PostgreSQL(9.0.1) x 3台体制
CentOS5.5 x86_64

全環境に、pgpool 3.0.3の
pgpool-recovery  pgpool-regclass  pgpool-walrecrunningはインストール済み

■pgpool 3.0.3
ScientificLinux

■pgpool.conf
#
# pgpool-II configuration file sample for Stream replication/Hot standby.
# $Header: /cvsroot/pgpool/pgpool-II/pgpool.conf.sample-stream,v 1.5
2010/09/01 04:58:47 kitagawa Exp $

# Host name or IP address to listen on: '*' for all, '' for no TCP/IP
# connections
#listen_addresses = 'localhost'
listen_addresses = '*'

# Port number for pgpool
#port = 9999
port = 5432

# Port number for pgpool communication manager
pcp_port = 9898

# Unix domain socket path.  (The Debian package defaults to
# /var/run/postgresql.)
socket_dir = '/tmp'

# Unix domain socket path for pgpool communication manager.
# (Debian package defaults to /var/run/postgresql)
pcp_socket_dir = '/tmp'

# Unix domain socket path for the backend. Debian package defaults to
/var/run/postgresql!
backend_socket_dir = '/tmp'

# pgpool communication manager timeout. 0 means no timeout. This
parameter is ignored now.
pcp_timeout = 10

# number of pre-forked child process
num_init_children = 32

# Number of connection pools allowed for a child process
max_pool = 4

# If idle for this many seconds, child exits.  0 means no timeout.
child_life_time = 300

# If idle for this many seconds, connection to PostgreSQL closes.
# 0 means no timeout.
connection_life_time = 300

# If child_max_connections connections were received, child exits.
# 0 means no exit.
child_max_connections = 0

# If client_idle_limit is n (n > 0), the client is forced to be
# disconnected whenever after n seconds idle (even inside an explicit
# transactions!)
# 0 means no disconnect.
client_idle_limit = 0

# Maximum time in seconds to complete client authentication.
# 0 means no timeout.
authentication_timeout = 60

# Logging directory
logdir = '/tmp'

# pid file name
pid_file_name = '/var/run/pgpool/pgpool.pid'

# Replication mode
replication_mode = false

# Load balancing mode, i.e., all SELECTs are load balanced.
load_balance_mode = true

# If there's a disagreement with the packet kind sent from backend,
# then degenrate the node which is most likely "minority".  If false,
# just force to exit this session.
replication_stop_on_mismatch = false

# If there's a disagreement with the number of affected tuples in
# UPDATE/DELETE, then degenrate the node which is most likely
# "minority".
# If false, just abort the transaction to keep the consistency.
failover_if_affected_tuples_mismatch = false

# If true, replicate SELECT statement when replication_mode or
parallel_mode is enabled.
# A priority of replicate_select is higher than load_balance_mode.
replicate_select = false

# Semicolon separated list of queries to be issued at the end of a
# session
reset_query_list = 'ABORT; DISCARD ALL'
# for 8.2 or older this should be as follows.
#reset_query_list = 'ABORT; RESET ALL; SET SESSION AUTHORIZATION DEFAULT'

# white_function_list is a comma separated list of function names
# those do not write to database. Any functions not listed here
# are regarded to write to database and SELECTs including such
# writer-functions will be executed on master(primary) in master/slave
# mode, or executed on all DB nodes in replication mode.
#
# black_function_list is a comma separated list of function names
# those write to database. Any functions not listed here
# are regarded not to write to database and SELECTs including such
# read-only-functions will be executed on any DB nodes.
#
# You cannot make full both white_function_list and
# black_function_list at the same time. If you specify something in
# one of them, you should make empty other.
#
# Pre 3.0 pgpool-II recognizes nextval and setval in hard coded
# way. Following setting will do the same as the previous version.
# white_function_list = ''
# black_function_list = 'nextval,setval'
white_function_list = ''
black_function_list = 'nextval,setval,currval,lastval'

# If true print timestamp on each log line.
print_timestamp = true

# If true, operate in master/slave mode.
master_slave_mode = true

# Master/slave sub mode. either 'slony' or 'stream'. Default is 'slony'.
master_slave_sub_mode = 'stream'

# If the standby server delays more than delay_threshold,
# any query goes to the primary only. The unit is in bytes.
# 0 disables the check. Default is 0.
# Note that health_check_period required to be greater than 0
# to enable the functionality.
delay_threshold = 10000000

# 'always' logs the standby delay whenever health check runs.
# 'if_over_threshold' logs only if the delay exceeds delay_threshold.
# 'none' disables the delay log.
log_standby_delay = 'if_over_threshold'

# If true, cache connection pool.
connection_cache = true

# Health check timeout.  0 means no timeout.
health_check_timeout = 20

# Health check period.  0 means no health check.
health_check_period = 0

# Health check user
health_check_user = 'nobody'

# Execute command by failover.
# special values:  %d = node id
#                  %h = host name
#                  %p = port number
#                  %D = database cluster path
#                  %m = new master node id
#                  %M = old master node id
#                  %% = '%' character
#
failover_command = ''

# Execute command by failback.
# special values:  %d = node id
#                  %h = host name
#                  %p = port number
#                  %D = database cluster path
#                  %m = new master node id
#                  %M = old master node id
#                  %% = '%' character
#
failback_command = ''

# If true, trigger fail over when writing to the backend communication
# socket fails. This is the same behavior of pgpool-II 2.2.x or
# earlier. If set to false, pgpool will report an error and disconnect
# the session.
fail_over_on_backend_error = true

# If true, automatically locks a table with INSERT statements to keep
# SERIAL data consistency.  If the data does not have SERIAL data
# type, no lock will be issued. An /*INSERT LOCK*/ comment has the
# same effect.  A /NO INSERT LOCK*/ comment disables the effect.
insert_lock = true

# If true, ignore leading white spaces of each query while pgpool judges
# whether the query is a SELECT so that it can be load balanced.  This
# is useful for certain APIs such as DBI/DBD which is known to adding an
# extra leading white space.
ignore_leading_white_space = true

# If true, print all statements to the log.  Like the log_statement option
# to PostgreSQL, this allows for observing queries without engaging in full
# debugging.
#log_statement = false
log_statement = true

# If true, print all statements to the log. Similar to log_statement except
# that prints DB node id and backend process id info.
#log_per_node_statement = false
log_per_node_statement = true

# If true, incoming connections will be printed to the log.
#log_connections = false
log_connections = true

# If true, hostname will be shown in ps status. Also shown in
# connection log if log_connections = true.
# Be warned that this feature will add overhead to look up hostname.
log_hostname = true

# if non 0, run in parallel query mode
parallel_mode = false

# if non 0, use query cache
enable_query_cache = false

#set pgpool2 hostname
pgpool2_hostname = ''

# system DB info
system_db_hostname = 'localhost'
system_db_port = 5433
system_db_dbname = 'pgpool'
system_db_schema = 'pgpool_catalog'
system_db_user = 'pgpool'
system_db_password = ''

# backend_hostname, backend_port, backend_weight
# here are examples
#backend_hostname0 = 'host1'
#backend_port0 = 5432
#backend_weight0 = 1
#backend_data_directory0 = '/data'
#backend_hostname1 = 'host2'
#backend_port1 = 5432
#backend_weight1 = 1
#backend_data_directory1 = '/data1'

backend_hostname0 = '192.168.3.240'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = '/home/postgres/9.0.1_5432/data'
backend_hostname1 = '192.168.3.240'
backend_port1 = 5433
backend_weight1 = 1
backend_data_directory1 = '/home/postgres/9.0.1_5433/data'
backend_hostname2 = '192.168.3.241'
backend_port2 = 5432
backend_weight2 = 1
backend_data_directory2 = '/home/postgres/9.0.1/data'

# - HBA -

# If true, use pool_hba.conf for client authentication.
enable_pool_hba = false

# - online recovery -
# online recovery user
recovery_user = 'nobody'

# online recovery password
recovery_password = ''

# execute a command in first stage.
#recovery_1st_stage_command = ''
#recovery_1st_stage_command = 'recovery_1st_stage.sh'

# execute a command in second stage.
recovery_2nd_stage_command = ''

# maximum time in seconds to wait for the recovering node's postmaster
# start-up. 0 means no wait.
# this is also used as a timer waiting for clients disconnected before
# starting 2nd stage
recovery_timeout = 90

# If client_idle_limit_in_recovery is n (n > 0), the client is forced
# to be disconnected whenever after n seconds idle (even inside an
# explicit transactions!) in the second stage of online recovery.
# n = -1 forces clients to be disconnected immediately.
# 0 disables this functionality(wait forever).
# This parameter only takes effect in recovery 2nd stage.
client_idle_limit_in_recovery = 0

# Specify table name to lock. This is used when rewriting lo_creat
# command in replication mode. The table must exist and has writable
# permission to public. If the table name is '', no rewriting occurs.
lobj_lock_table = ''

# If true, enable SSL support for both frontend and backend connections.
# note that you must also set ssl_key and ssl_cert for SSL to work in
# the frontend connections.
ssl = false
# path to the SSL private key file
#ssl_key = './server.key'
# path to the SSL public certificate file
#ssl_cert = './server.cert'

# If either ssl_ca_cert or ssl_ca_cert_dir is set, then certificate
# verification will be performed to establish the authenticity of the
# certificate.  If neither is set to a nonempty string then no such
# verification takes place.  ssl_ca_cert should be a path to a single
# PEM format file containing CA root certificate(s), whereas ssl_ca_cert_dir
# should be a directory containing such files.  These are analagous to the
# -CAfile and -CApath options to openssl verify(1), respectively.
#ssl_ca_cert = ''
#ssl_ca_cert_dir = ''

# Debug message verbosity level. 0: no message, 1 <= : more verbose
debug_level = 0

以上、宜しくお願い致します。