= PostgreSQL Configuration =

PostgreSQL can be configured at startup through a configuration file or by command line options.

<<TableOfContents>>

----



== Syntax ==

The configuration file should consist of lines like `parameter = value`. The `=` is optional.

Anything following a `#` is a comment.

Time and memory are expressed in terms of the below units.

||'''Memory Unit'''||'''Configuration Syntax'''||
||bytes            ||`B`                       ||
||kilobytes        ||`kB`                      ||
||megabytes        ||`MB`                      ||
||gigabytes        ||`GB`                      ||
||terabytes        ||`TB`                      ||

||'''Time Unit'''||'''Configuration Syntax'''||
||microseconds   ||`us`                      ||
||milliseconds   ||`ms`                      ||
||seconds        ||`s`                       ||
||minutes        ||`min`                     ||
||hours          ||`h`                       ||
||days           ||`d`                       ||

----



== Example ==

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

# The default values of these variables are driven from the -D command-line
# option or PGDATA environment variable

data_directory = '/var/lib/postgresql/data'             # use data in another directory
hba_file = '/var/lib/postgresql/data/pg_hba.conf'       # host-based authentication file
ident_file = '/var/lib/postgresql/data/pg_ident.conf'   # ident configuration file

# If external_pid_file is not explicitly set, no extra PID file is written.
#external_pid_file = ''                                 # write an extra PID file


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

# - Connection Settings -

listen_addresses = 'localhost'                # comma-separated list of addresses; defaults to 'localhost'; use '*' for all
port = 5432
#max_connections = 100
#superuser_reserved_connections = 3
unix_socket_directories = '/run/postgresql'   # comma-separated list of directories
#unix_socket_group = ''
#unix_socket_permissions = 0777               # begin with 0 to use octal notation
bonjour = off
#bonjour_name = ''                            # defaults to the computer name

# - TCP settings -
# see "man 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
tcp_user_timeout = 0                   # TCP_USER_TIMEOUT, in milliseconds; 0 selects the system default

client_connection_check_interval = 0   # time between checks for client disconnection while running queries; 0 for never

# - Authentication -

#authentication_timeout = 1min         # 1s-600s
#password_encryption = scram-sha-256   # scram-sha-256 or md5
#db_user_namespace = off

# GSSAPI using Kerberos
#krb_server_keyfile = 'FILE:${sysconfdir}/krb5.keytab'
#krb_caseins_users = off

# - SSL -

#ssl = off
#ssl_ca_file = ''
#ssl_cert_file = 'server.crt'
#ssl_crl_file = ''
#ssl_crl_dir = ''
#ssl_key_file = 'server.key'
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL'        # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_min_protocol_version = 'TLSv1.2'
#ssl_max_protocol_version = ''
#ssl_dh_params_file = ''
#ssl_passphrase_command = ''
#ssl_passphrase_command_supports_reload = off


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

# - Memory -

#shared_buffers = 32MB                 # min 128kB
#huge_pages = try                      # on, off, or try
#huge_page_size = 0                    # zero for system default
#temp_buffers = 8MB                    # min 800kB
#max_prepared_transactions = 0         # zero disables the feature; it is not advisable to set nonzero unless you actively intend to use prepared transactions
#work_mem = 4MB                        # min 64kB
#hash_mem_multiplier = 1.0             # 1-1000.0 multiplier on hash table work_mem
#maintenance_work_mem = 64MB           # min 1MB
#autovacuum_work_mem = -1              # min 1MB, or -1 to use maintenance_work_mem
#logical_decoding_work_mem = 64MB      # min 64kB
#max_stack_depth = 2MB                 # min 100kB
#shared_memory_type = mmap             # the default is the first option supported by the operating system: mmap, sysv, windows
#dynamic_shared_memory_type = posix    # the default is the first option supported by the operating system: posix, sysv, windows, mmap
#min_dynamic_shared_memory = 0MB

# - Disk -

#temp_file_limit = -1   # limits per-process temp file space in kilobytes, or -1 for no limit

# - Kernel Resources -

#max_files_per_process = 1000   # min 64

# - Cost-Based Vacuum Delay -

#vacuum_cost_delay = 0         # 0-100 milliseconds (0 disables)
#vacuum_cost_page_hit = 1      # 0-10000 credits
#vacuum_cost_page_miss = 2     # 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     # max buffers written/round, 0 disables
#bgwriter_lru_multiplier = 2.0   # 0-10.0 multiplier on buffers scanned/round
#bgwriter_flush_after = 0        # measured in pages, 0 disables

# - Asynchronous Behavior -

#backend_flush_after = 0                # measured in pages, 0 disables
#effective_io_concurrency = 1           # 1-1000; 0 disables prefetching
#maintenance_io_concurrency = 10        # 1-1000; 0 disables prefetching
#max_worker_processes = 8               # (change requires restart)
#max_parallel_workers_per_gather = 2    # taken from max_parallel_workers
#max_parallel_maintenance_workers = 2   # taken from max_parallel_workers
#max_parallel_workers = 8               # maximum number of max_worker_processes that can be used in parallel operations
#parallel_leader_participation = on
#old_snapshot_threshold = -1            # 1min-60d; -1 disables; 0 is immediate


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

# - Settings -

#wal_level = replica             # minimal, replica, or logical
#fsync = on                      # flush data to disk for crash safety (turning this off can cause unrecoverable data corruption)
#synchronous_commit = on         # synchronization level; off, local, remote_write, remote_apply, on
#wal_sync_method = fsync         # the default is the first option supported by the operating system: open_datasync, fdatasync (default on Linux and FreeBSD), fsync, fsync_writethrough, open_sync
#full_page_writes = on           # recover from partial page writes
#wal_log_hints = off             # also do full page writes of non-critical updates
#wal_compression = off           # enable compression of full-page writes
#wal_init_zero = on              # zero-fill new WAL files
#wal_recycle = on                # recycle WAL files
#wal_buffers = -1                # min 32kB, -1 sets based on shared_buffers
#wal_writer_delay = 200ms        # 1-10000 milliseconds
#wal_writer_flush_after = 1MB    # measured in pages, 0 disables
#wal_skip_threshold = 2MB

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

# - Checkpoints -

#checkpoint_timeout = 5min             # range 30s-1d
#checkpoint_completion_target = 0.9    # checkpoint target duration, 0.0 - 1.0
#checkpoint_flush_after = 0            # measured in pages, 0 disables
#checkpoint_warning = 30s              # 0 disables
#max_wal_size = 1GB
#min_wal_size = 80MB

# - Archiving -

#archive_mode = off     # enables archiving; off, on, or always
#Placeholders for archive_command and restore_command:
# %p = path of file to archive
# %f = file name only
#archive_command = ''   # command to use to archive a logfile segment; placeholders: %p = path of file to archive, %f = file name only
#archive_timeout = 0    # force a logfile segment switch after this number of seconds; 0 disables

# - Archive Recovery -

# These are only used in recovery mode.

#restore_command = ''           # command to use to restore an archived logfile segment
#archive_cleanup_command = ''   # command to execute at every restartpoint; see placeholders on line 198
#recovery_end_command = ''      # command to execute at completion of recovery

# - Recovery Target -

# Set these only when performing a targeted recovery.

#recovery_target = ''                   # 'immediate' to end recovery as soon as a consistent state is reached
#recovery_target_name = ''              # the named restore point to which recovery will proceed
#recovery_target_time = ''              # the time stamp up to which recovery will proceed
#recovery_target_xid = ''               # the transaction ID up to which recovery will proceed
#recovery_target_lsn = ''               # the WAL LSN up to which recovery will proceed
#recovery_target_inclusive = on         # Specifies whether to stop: just after the specified recovery target (on), or just before the recovery target (off)
#recovery_target_timeline = 'latest'    # 'current', 'latest', or timeline ID
#recovery_target_action = 'pause'       # 'pause', 'promote', 'shutdown'


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

# - Sending Servers -

# Set these on the primary and on any standby that will send replication data.

#max_wal_senders = 10            # max number of walsender processes
#max_replication_slots = 10      # max number of replication slots
#wal_keep_size = 0               # in megabytes; 0 disables
#max_slot_wal_keep_size = -1     # in megabytes; -1 disables
#wal_sender_timeout = 60s        # in milliseconds; 0 disables
#track_commit_timestamp = off    # collect timestamp of transaction commit

# - Primary Server -

# These settings are ignored on a standby server.

#synchronous_standby_names = ''   # standby servers that provide sync rep method to choose sync standbys, number of sync standbys, and comma-separated list of application_name from standby(s); '*' = all
#vacuum_defer_cleanup_age = 0     # number of xacts by which cleanup is delayed

# - Standby Servers -

# These settings are ignored on a primary server.

#primary_conninfo = ''                  # connection string to sending server
#primary_slot_name = ''                 # replication slot on sending server
#promote_trigger_file = ''              # file name whose presence ends recovery
#hot_standby = on                       # "off" disallows queries during recovery
#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_create_temp_slot = off    # create temp slot if primary_slot_name is not set
#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
#wal_receiver_timeout = 60s             # time that receiver waits for communication from primary in milliseconds; 0 disables
#wal_retrieve_retry_interval = 5s       # time to wait before retrying to retrieve WAL after a failed attempt
#recovery_min_apply_delay = 0           # minimum delay for applying changes during recovery

# - Subscribers -

# These settings are ignored on a publisher.

#max_logical_replication_workers = 4      # taken from max_worker_processes
#max_sync_workers_per_subscription = 2    # taken from max_logical_replication_workers


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

# - Planner Method Configuration -

#enable_async_append = on
#enable_bitmapscan = on
#enable_gathermerge = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_incremental_sort = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = on
#enable_memoize = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_parallel_append = on
#enable_parallel_hash = on
#enable_partition_pruning = on
#enable_partitionwise_join = off
#enable_partitionwise_aggregate = off
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on

# - Planner Cost Constants -

#seq_page_cost = 1.0                     # measured on an arbitrary scale
#random_page_cost = 4.0                  # 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
#parallel_setup_cost = 1000.0            # same scale as above
#parallel_tuple_cost = 0.1               # same scale as above
#min_parallel_table_scan_size = 8MB
#min_parallel_index_scan_size = 512kB
#effective_cache_size = 4GB

#jit_above_cost = 100000                 # perform JIT compilation if available and query more expensive than this; -1 disables
#jit_inline_above_cost = 500000          # inline small functions if query is more expensive than this; -1 disables
#jit_optimize_above_cost = 500000        # use expensive JIT optimizations if query is more expensive than this; -1 disables

# - 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 -

#default_statistics_target = 100     # range 1-10000
#constraint_exclusion = partition    # on, off, or partition
#cursor_tuple_fraction = 0.1         # range 0.0-1.0
#from_collapse_limit = 8
#jit = on                            # allow JIT compilation
#join_collapse_limit = 8             # 1 disables collapsing of explicit JOIN clauses
#plan_cache_mode = auto              # auto, force_generic_plan or force_custom_plan


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

# - Where to Log -

log_destination = 'stderr'                         # 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:
logging_collector = off                            # Enable capturing of stderr and csvlog into log files. Required to be on for csvlogs.

# These are only used if logging_collector is on:
#log_directory = '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_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.
#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.

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

# This is only relevant when logging to eventlog (Windows):
#event_source = 'PostgreSQL'

# - When to Log -

# Values for log_min_messages and log_min_error_statement:
#  debug5
#  debug4
#  debug3
#  debug2
#  debug1
#  info
#  notice
#  warning
#  error
#  log
#  fatal
#  panic
log_min_messages = info

log_min_error_statement = info                     # see values on line 368; panic = effectively off

#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

#log_min_duration_sample = -1                      # -1 is disabled, 0 logs a sample of statements and their durations, > 0 logs only a sample of statements running at least this number of milliseconds; sample fraction is determined by log_statement_sample_rate

#log_statement_sample_rate = 1.0                   # fraction of logged statements exceeding log_min_duration_sample to be logged; 1.0 logs all such statements, 0.0 never logs


#log_transaction_sample_rate = 0.0                 # fraction of transactions whose statements are logged regardless of their duration; 1.0 logs all statements from all transactions, 0.0 never logs

# - What to Log -

#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = on
#log_autovacuum_min_duration = -1         # log autovacuum activity; -1 disables, 0 logs all actions and their durations, > 0 logs only actions running at least this number of milliseconds.
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_error_verbosity = default            # terse, default, or verbose messages
#log_hostname = off
# Placeholders for log_line_prefix:
# %a = application name
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %b = backend type
# %p = process ID
# %P = process ID of parallel group leader
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)
# %Q = query ID (0 if none or not computed)
# %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
# %% = '%'
#log_line_prefix = '%m [%p] '
#log_lock_waits = off                     # log lock waits >= deadlock_timeout
#log_recovery_conflict_waits = off        # log standby recovery conflict waits >= deadlock_timeout
#log_parameter_max_length = -1            # when logging statements, limit logged bind-parameter values to N bytes; -1 means print in full, 0 disables
#log_parameter_max_length_on_error = 0    # when logging an error, limit logged bind-parameter values to N bytes; -1 means print in full, 0 disables
#log_statement = 'none'                   # none, ddl, mod, all
#log_replication_commands = off
#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 = 'GMT'


#------------------------------------------------------------------------------
# PROCESS TITLE
#------------------------------------------------------------------------------

#cluster_name = ''            # added to process titles if nonempty
#update_process_title = on


#------------------------------------------------------------------------------
# STATISTICS
#------------------------------------------------------------------------------

# - Query and Index Statistics Collector -

#track_activities = on
#track_activity_query_size = 1024
#track_counts = on
#track_io_timing = off
#track_wal_io_timing = off
#track_functions = none                 # none, pl, all
#stats_temp_directory = 'pg_stat_tmp'


# - Monitoring -

#compute_query_id = auto
#log_statement_stats = off
#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off


#------------------------------------------------------------------------------
# AUTOVACUUM
#------------------------------------------------------------------------------

#autovacuum = on                                    # Enable autovacuum subprocess?  'on' requires track_counts to also be on.
#autovacuum_max_workers = 3                         # max number of autovacuum subprocesses
#autovacuum_naptime = 1min                          # time between autovacuum runs
#autovacuum_vacuum_threshold = 50                   # min number of row updates before vacuum
#autovacuum_vacuum_insert_threshold = 1000          # min number of row inserts before vacuum; -1 disables insert vacuums
#autovacuum_analyze_threshold = 50                  # min number of row updates before analyze
#autovacuum_vacuum_scale_factor = 0.2               # fraction of table size before vacuum
#autovacuum_vacuum_insert_scale_factor = 0.2        # fraction of inserts over table size before insert vacuum
#autovacuum_analyze_scale_factor = 0.1              # fraction of table size before analyze
#autovacuum_freeze_max_age = 200000000              # maximum XID age before forced vacuum
#autovacuum_multixact_freeze_max_age = 400000000    # maximum multixact age before forced vacuum
#autovacuum_vacuum_cost_delay = 2ms                 # 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 -

# Values for client_min_messages:
#  debug5
#  debug4
#  debug3
#  debug2
#  debug1
#  log
#  notice
#  warning
#  error
#client_min_messages = notice
#search_path = '"$user", public'                    # schema names
#row_security = on
#default_table_access_method = 'heap'
#default_tablespace = ''                            # a tablespace name, '' uses the default
#default_toast_compression = 'pglz'                 # 'pglz' or 'lz4'
#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
#lock_timeout = 0                                   # in milliseconds, 0 is disabled
#idle_in_transaction_session_timeout = 0            # in milliseconds, 0 is disabled
#idle_session_timeout = 0                           # in milliseconds, 0 is disabled
#vacuum_freeze_table_age = 150000000
#vacuum_freeze_min_age = 50000000
#vacuum_failsafe_age = 1600000000
#vacuum_multixact_freeze_table_age = 150000000
#vacuum_multixact_freeze_min_age = 5000000
#vacuum_multixact_failsafe_age = 1600000000
#bytea_output = 'hex'                               # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'
#gin_pending_list_limit = 4MB

# - Locale and Formatting -

#datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
#timezone = 'GMT'
#timezone_abbreviations = 'Default'                  # Select the set of available time zone abbreviations; Default, Australia (historical usage), India; You can create your own file in share/timezonesets/.
#extra_float_digits = 1                              # min -15, max 3; any value >0 actually selects precise output mode
#client_encoding = sql_ascii                         # actually, defaults to database encoding

# These settings are initialized by initdb, but they can be changed.
#lc_messages = 'C'                                   # locale for system error message strings
#lc_monetary = 'C'                                   # locale for monetary formatting
#lc_numeric = 'C'                                    # locale for number formatting
#lc_time = 'C'                                       # locale for time formatting

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

# - Shared Library Preloading -

#local_preload_libraries = ''
#session_preload_libraries = ''
#shared_preload_libraries = ''    # (change requires restart)
#jit_provider = 'llvmjit'         # JIT library to use

# - Other Defaults -

#dynamic_library_path = '$libdir'
#gin_fuzzy_search_limit = 0


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

#deadlock_timeout = 1s
#max_locks_per_transaction = 64         # min 10
#max_pred_locks_per_transaction = 64    # min 10
#max_pred_locks_per_relation = -2       # negative values mean; (max_pred_locks_per_transaction / -max_pred_locks_per_relation) - 1
#max_pred_locks_per_page = 2            # min 0


#------------------------------------------------------------------------------
# VERSION AND PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------

# - Previous PostgreSQL Versions -

#array_nulls = on
#backslash_quote = safe_encoding     # on, off, or safe_encoding
#escape_string_warning = on
#lo_compat_privileges = off
#quote_all_identifiers = off
#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?
#data_sync_retry = off                # retry or panic on failure to fsync data?
#recovery_init_sync_method = fsync    # fsync, syncfs (Linux 5.8+)


#------------------------------------------------------------------------------
# CONFIG FILE INCLUDES
#------------------------------------------------------------------------------

# These options allow settings to be loaded from files other than the
# default postgresql.conf.  Note that these are directives, not variable
# assignments, so they can usefully be given more than once.

#include_dir = '...'          # include files ending in '.conf' from a directory, e.g., 'conf.d'
#include_if_exists = '...'    # include file only if it exists
#include = '...'              # include file
}}}



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