PostgreSQL tuning example for 9.1 postgresql.conf

Each tuning is almost unique. We show postgresql.conf file for 9.1 version as a starting point on Debian GNU/Linux systems.

These examples were deployed for a given major query profile, discovered using PgFouine.

Also, the hardware played critical role in the tuning choices. A powerful 16 cores Xeon, with 32 GB ECC RAM enterprise server, connected to a Fiber Channel Data Storage Server with FC disks and many GB of NVRAM.

The data storage server is a key to the performance.

It behaves (latency and IOPS wise) like a giant Enterprise SSD. Also, allows the simultaneous I/O to be so high. This kind of storage server allows a reduced random page cost too.

The approach MUST have a connection pooling software like PgPool-II in front of the server, in order to limit the simultaneous connections to 250.

You have to read the previous articles regarding Debian Postgresql database cluster instances creation and PostgreSQL advanced hardware and software tuning.

Do not forget to read the whole ZFS filesystem data server series, as well as virtualization, kernel , storage ,multipath, and file system tuning series and extreme zfs tuning at this blog.

You MUST HAVE to read the biblography, the previous articles and the file example comments. The default modifications where all commented starting with "#AFM".

Database tuning is a whole context task.

Keep an eye at the postgresql and system logs. They offer valuable hints about some errors, misconfigurations or insufficient resources.

At this article we do not address the kernel, network, connection pooling, filesystem tuning for some scenarios. Read the previous articles and bibliography.

There are modification specifically to use PgFouine for query profiling.

It is a starting point. You have to adapt to your query profiles and hardware. These tuning configurations were successful at a given scenario only.

ECC RAM and data storage performance plays extremely critical role in PostgreSQL tuning.

/etc/postgresql/9.1/main/postgresql.conf

# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
# name = value
#
# (The "=" is optional.) 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 PostgreSQL documentation.
#
# The commented-out settings shown in this file represent the default values.
# Re-commenting a setting is NOT sufficient to revert it to the default value;
# you need to reload the server.
#
# 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 "pg_ctl reload". Some
# parameters, which are marked below, require a server shutdown and restart to
# take effect.
#
# Any parameter can also be given as a command-line option to the server, e.g.,
# "postgres -c log_connections=on". Some parameters can be changed at run time
# with the "SET" SQL command.
#
# Memory units: kB = kilobytes Time units: ms = milliseconds
# MB = megabytes s = seconds
# GB = gigabytes min = minutes
# h = hours
# d = days

#------------------------------------------------------------------------------
# FILE LOCATIONS
#------------------------------------------------------------------------------

# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable, represented here as ConfigDir.

data_directory = '/data/postgresql' # use data in another directory
# (change requires restart)
hba_file = '/etc/postgresql/9.1/main/pg_hba.conf' # host-based authentication file
# (change requires restart)
ident_file = '/etc/postgresql/9.1/main/pg_ident.conf' # ident configuration file
# (change requires restart)

# If external_pid_file is not explicitly set, no extra PID file is written.
external_pid_file = '/var/run/postgresql/9.1-main.pid' # write an extra PID file
# (change requires restart)

#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------

# - Connection Settings -

#AFM 20121109
listen_addresses = '*' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost', '*' = all
# (change requires restart)
port = 5432 # (change requires restart)
#AFM 20121009 work_mem high for complex queries limit viable max connections
#AFM 20121009 use connection pooling or lazy connections
max_connections = 250 # (change requires restart)
# Note: Increasing max_connections costs ~400 bytes of shared memory per
# connection slot, plus lock space (see max_locks_per_transaction).
#superuser_reserved_connections = 3 # (change requires restart)
unix_socket_directory = '/var/run/postgresql' # (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
# (change requires restart)
#bonjour = off # advertise server via Bonjour
# (change requires restart)
#bonjour_name = '' # defaults to the computer name
# (change requires restart)

# - Security and Authentication -

#authentication_timeout = 1min # 1s-600s
ssl = true # (change requires restart)
#ssl_ciphers = 'ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH' # allowed SSL ciphers
# (change requires restart)
#ssl_renegotiation_limit = 512MB # amount of data between renegotiations
#password_encryption = on
#db_user_namespace = off

# Kerberos and GSSAPI
#krb_server_keyfile = ''
#krb_srvname = 'postgres' # (Kerberos only)
#krb_caseins_users = off

# - TCP Keepalives -
# see "man 7 tcp" for details

#tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0 # TCP_KEEPCNT;
# 0 selects the system default

#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------

# - Memory -
#AFM 20121008 (ram / 4)
shared_buffers = 8GB # min 128kB
# (change requires restart)
#temp_buffers = 8MB # min 800kB
#max_prepared_transactions = 0 # zero disables the feature
# (change requires restart)
# Note: Increasing max_prepared_transactions costs ~600 bytes of shared memory
# per transaction slot, plus lock space (see max_locks_per_transaction).
# It is not advisable to set max_prepared_transactions nonzero unless you
# actively intend to use prepared transactions.
#AFM 20121009 from 10mb to 16MB : (ram / max_connections / 4)
#AFM 20121009 divide by 4 for complex queries with sorts that need much ram
work_mem = 32MB # min 64kB
#AFM 20121008 from 16 MB to (50MB x YGB ram)
maintenance_work_mem = 128MB # min 1MB
#max_stack_depth = 2MB # min 100kB

# - Kernel Resource Usage -

#max_files_per_process = 1000 # min 25
# (change requires restart)
#shared_preload_libraries = '' # (change requires restart)

# - Cost-Based Vacuum Delay -

#vacuum_cost_delay = 0ms # 0-100 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 1-10000 credits

# - Background Writer -

#bgwriter_delay = 200ms # 10-10000ms between rounds
#bgwriter_lru_maxpages = 100 # 0-1000 max buffers written/round
#bgwriter_lru_multiplier = 2.0 # 0-10.0 multipler on buffers scanned/round

# - Asynchronous Behavior -

#AFM 20121009 from 1 to 1000, whe have powerful storage
effective_io_concurrency = 1000 # 1-1000. 0 disables prefetching

#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------

# - Settings -

#wal_level = minimal # minimal, archive, or hot_standby
# (change requires restart)
#fsync = on # turns forced synchronization on or off
#synchronous_commit = on # synchronization level; on, off, or local
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync (default on Linux)
# fsync
# fsync_writethrough
# open_sync
#full_page_writes = on # recover from partial page writes
#AFM 20121008 from 64kB to 8MB whe have a powerful server
#wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers
# (change requires restart)
#wal_writer_delay = 200ms # 1-10000 milliseconds

#commit_delay = 0 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000

# - Checkpoints -

#checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
#checkpoint_timeout = 5min # range 30s-1h
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_warning = 30s # 0 disables

# - Archiving -

#archive_mode = off # allows archiving to be done
# (change requires restart)
#archive_command = '' # command to use to archive a logfile segment
#archive_timeout = 0 # force a logfile segment switch after this
# number of seconds; 0 disables

#------------------------------------------------------------------------------
# REPLICATION
#------------------------------------------------------------------------------

# - Master Server -

# These settings are ignored on a standby server

#max_wal_senders = 0 # max number of walsender processes
# (change requires restart)
#wal_sender_delay = 1s # walsender cycle time, 1-10000 milliseconds
#wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables
#vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed
#replication_timeout = 60s # in milliseconds; 0 disables
#synchronous_standby_names = '' # standby servers that provide sync rep
# comma-separated list of application_name
# from standby(s); '*' = all

# - Standby Servers -

# These settings are ignored on a master server

#hot_standby = off # "on" allows queries during recovery
# (change requires restart)
#max_standby_archive_delay = 30s # max delay before canceling queries
# when reading WAL from archive;
# -1 allows indefinite delay
#max_standby_streaming_delay = 30s # max delay before canceling queries
# when reading streaming WAL;
# -1 allows indefinite delay
#wal_receiver_status_interval = 10s # send replies at least this often
# 0 disables
#hot_standby_feedback = off # send info from standby to prevent
# query conflicts

#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------

# - Planner Method Configuration -

#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_material = on
#enable_mergejoin = on
#enable_nestloop = on
#AFM 20121009 off not always best performance
enable_seqscan = on
#enable_sort = on
#enable_tidscan = on

# - Planner Cost Constants -

#seq_page_cost = 1.0 # measured on an arbitrary scale
#AFM 20121009 from 4.0 to 1.1 because very fast data storage like ssd
random_page_cost = 1.1 # same scale as above
#cpu_tuple_cost = 0.01 # same scale as above
#cpu_index_tuple_cost = 0.005 # same scale as above
#cpu_operator_cost = 0.0025 # same scale as above
#AFM 20121009 from 128mb to (0.5 * ram size)
effective_cache_size = 16GB

# - Genetic Query Optimizer -

#geqo = on
#geqo_threshold = 12
#geqo_effort = 5 # range 1-10
#geqo_pool_size = 0 # selects default based on effort
#geqo_generations = 0 # selects default based on effort
#geqo_selection_bias = 2.0 # range 1.5-2.0
#geqo_seed = 0.0 # range 0.0-1.0

# - Other Planner Options -

#AFM 20121008 from 100 to 1000
default_statistics_target = 1000 # range 1-10000
#constraint_exclusion = partition # on, off, or partition
#cursor_tuple_fraction = 0.1 # range 0.0-1.0
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses

#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------

# - Where to Log -

#AFM 20121009 stderr for pgfouine multiline, you must read the log file
#AFM 20121009 /var/lib/postgresql/9.1/main/pg_log/postgresql-2012-10-09_151331.log
#AFM 20121009 DANGER: stderr does not rotate!!! use only at development
#AFM 20121009 instead of syslog's /var/log/postgresql/postgresql-9.1-main.log
log_destination = 'syslog' # Valid values are combinations of
# stderr, csvlog, syslog, and eventlog,
# depending on platform. csvlog
# requires logging_collector to be on.

# This is used when logging to stderr:
#AFM 20121008 for pgfouine on
logging_collector = off # Enable capturing of stderr and csvlog
# into log files. Required to be on for
# csvlogs.
# (change requires restart)

# These are only used if logging_collector is on:
#log_directory = 'pg_log' # directory where log files are written,
# can be absolute or relative to PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern,
# can include strftime() escapes
#log_file_mode = 0600 # creation mode for log files,
# begin with 0 to use octal notation
#log_truncate_on_rotation = off # If on, an existing log file with the
# same name as the new log file will be
# truncated rather than appended to.
# But such truncation only occurs on
# time-driven rotation, not on restarts
# or size-driven rotation. Default is
# off, meaning append to existing files
# in all cases.
#log_rotation_age = 1d # Automatic rotation of logfiles will
# happen after that time. 0 disables.
#log_rotation_size = 10MB # Automatic rotation of logfiles will
# happen after that much log output.
# 0 disables.

# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'

#AFM 20121008 for pgfouine on
#silent_mode = off # Run server silently.
# DO NOT USE without syslog or
# logging_collector
# (change requires restart)

# - When to Log -

#client_min_messages = notice # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# log
# notice
# warning
# error

#log_min_messages = warning # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic

#log_min_error_statement = error # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic (effectively off)

#AFM 20121008 for pgfouine set some threshold time
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
# and their durations, > 0 logs only
# statements running at least this number
# of milliseconds

# - What to Log -

#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#AFM 20121009 on for pgfouine
#log_duration = off
#log_error_verbosity = default # terse, default, or verbose messages
#log_hostname = off
#AFM 20121009 pgfouine multiline statements [%l-1]
#AFM 20121009 pgfouine '%t [%p]: [%l-1] ' from '%t-%u-%d:'
log_line_prefix = '%t [%p]: [%l-1] ' # special values:
# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %p = process ID
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %i = command tag
# %e = SQL state
# %c = session ID
# %l = session line number
# %s = session start timestamp
# %v = virtual transaction ID
# %x = transaction ID (0 if none)
# %q = stop here in non-session
# processes
# %% = '%'
# e.g. '<%u%%%d> '
#log_lock_waits = off # log lock waits >= deadlock_timeout
#AFM 20121009 none for pgfouine
#log_statement = 'none' # none, ddl, mod, all
#log_temp_files = -1 # log temporary files equal or larger
# than the specified size in kilobytes;
# -1 disables, 0 logs all temp files
#log_timezone = '(defaults to server environment setting)'

#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------

# - Query/Index Statistics Collector -

#track_activities = on
#track_counts = on
#track_functions = none # none, pl, all
#track_activity_query_size = 1024 # (change requires restart)
#update_process_title = on
#stats_temp_directory = 'pg_stat_tmp'

# - Statistics Monitoring -

#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off

#------------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#------------------------------------------------------------------------------

#autovacuum = on # Enable autovacuum subprocess? 'on'
# requires track_counts to also be on.
#log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and
# their durations, > 0 logs only
# actions running at least this number
# of milliseconds.
#autovacuum_max_workers = 3 # max number of autovacuum subprocesses
# (change requires restart)
#autovacuum_naptime = 1min # time between autovacuum runs
#autovacuum_vacuum_threshold = 50 # min number of row updates before
# vacuum
#autovacuum_analyze_threshold = 50 # min number of row updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum
#autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for
# autovacuum, in milliseconds;
# -1 means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit

#------------------------------------------------------------------------------
# CLIENT CONNECTION DEFAULTS
#------------------------------------------------------------------------------

# - Statement Behavior -

#search_path = '"$user",public' # schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#default_transaction_deferrable = off
#session_replication_role = 'origin'
#statement_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#bytea_output = 'hex' # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'

# - Locale and Formatting -

datestyle = 'iso, dmy'
#intervalstyle = 'postgres'
#timezone = '(defaults to server environment setting)'
#timezone_abbreviations = 'Default' # Select the set of available time zone
# abbreviations. Currently, there are
# Default
# Australia
# India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 0 # min -15, max 3
#client_encoding = sql_ascii # actually, defaults to database
# encoding

# These settings are initialized by initdb, but they can be changed.
#AFM 20121009 for pgfouine en_US.UTF-8 from pt_BR.UTF-8
lc_messages = 'en_US.UTF-8' # locale for system error message
# strings
lc_monetary = 'pt_BR.UTF-8' # locale for monetary formatting
lc_numeric = 'pt_BR.UTF-8' # locale for number formatting
lc_time = 'pt_BR.UTF-8' # locale for time formatting

# default configuration for text search
default_text_search_config = 'pg_catalog.portuguese'

# - Other Defaults -

#dynamic_library_path = '$libdir'
#local_preload_libraries = ''

#------------------------------------------------------------------------------
# LOCK MANAGEMENT
#------------------------------------------------------------------------------

#deadlock_timeout = 1s
#max_locks_per_transaction = 64 # min 10
# (change requires restart)
# Note: Each lock table slot uses ~270 bytes of shared memory, and there are
# max_locks_per_transaction * (max_connections + max_prepared_transactions)
# lock table slots.
#max_pred_locks_per_transaction = 64 # min 10
# (change requires restart)

#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------

# - Previous PostgreSQL Versions -

#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#lo_compat_privileges = off
#quote_all_identifiers = off
#sql_inheritance = on
#standard_conforming_strings = on
#synchronize_seqscans = on

# - Other Platforms and Clients -

#transform_null_equals = off

#------------------------------------------------------------------------------
# ERROR HANDLING
#------------------------------------------------------------------------------

#exit_on_error = off # terminate session on any error?
#restart_after_crash = on # reinitialize after backend crash?

#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------

#custom_variable_classes = '' # list of custom variable class names

/etc/fstab

This time, we used the approach to minimize I/O wait times for logging on /var/log. Also, disabling write barriers is viable ONLY if you have a data storage server with ECC NVRAM.

You must have to read the bibliography and previous articles.

Test, test, test.

# /etc/fstab: static file system information.
#AFM 20121015
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc defaults 0 0
/dev/disk/by-id/scsi-360024e805520f9001270b63307b03f4c-part3 / ext3 barrier=0,norelatime,noatime,nodiratime,async,commit=5,reservation,errors=remount-ro 0 1
/dev/disk/by-id/scsi-360024e805520f9001270b63307b03f4c-part1 /boot ext3 defaults 0 2
/dev/disk/by-id/scsi-360024e805520f9001270b63307b03f4c-part2 none swap sw 0 0
/dev/scd0 /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/grupo1/volume1 /data xfs noatime,nodiratime,attr2,nobarrier,logbufs=8,logbsize=256k,osyncisdsync 0 0