我已经玩了几天 postgresql.conf 文件了。我想知道你们喜欢定制哪些变量，为什么？
这是该文件的示例：
# - 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 -
shared_buffers = 64MB # min 128kB or max_connections*16kB
# (change requires restart)
#temp_buffers = 8MB # min 800kB
#max_prepared_transactions = 5 # can be 0 or more
# (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).
#work_mem = 1MB # min 64kB
#maintenance_work_mem = 16MB # min 1MB
#max_stack_depth = 2MB # min 100kB
# - Free Space Map -
max_fsm_pages = 204800 # min max_fsm_relations*16, 6 bytes each
# (change requires restart)
#max_fsm_relations = 1000 # min 100, ~70 bytes each
# (change requires restart)
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
# (change requires restart)
shared_preload_libraries = '$libdir/plugins/plugin_debugger.dll' # (change requires restart)
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0 # 0-1000 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
#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------
# - Settings -
#fsync = on # turns forced synchronization on or off
#synchronous_commit = on # immediate fsync at commit
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync
# fsync
# fsync_writethrough
# open_sync
#full_page_writes = on # recover from partial page writes
#wal_buffers = 64kB # min 32kB
# (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 is off
# - 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
# time; 0 is off
#------------------------------------------------------------------------------
# QUERY TUNING
#------------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_mergejoin = on
#enable_nestloop = on
#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
effective_cache_size = 32768
# - 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
# - Other Planner Options -
#default_statistics_target = 10 # range 1-1000
#constraint_exclusion = off
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
# JOIN clauses
#------------------------------------------------------------------------------
# ERROR 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 = on # 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_truncate_on_rotation = off # If on, an existing log file of 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 to disable.
#log_rotation_size = 10MB # Automatic rotation of logfiles will
# happen after that much log output.
# 0 to disable.
# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'
# - 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 = notice # values in order of decreasing detail:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# log
# fatal
# panic
#log_error_verbosity = default # terse, default, or verbose messages
#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)
#log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements
# and their durations, > 0 logs only
# statements running at least this time.
#silent_mode = off # DO NOT USE without syslog or
# logging_collector
# (change requires restart)
# - What to Log -
#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = off
#log_checkpoints = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_hostname = off
log_line_prefix = '%t ' # special values:
# %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
# %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
#log_statement = 'none' # none, ddl, mod, all
#log_temp_files = -1 # log temporary files equal or larger
# than specified size;
# -1 disables, 0 logs all temp files
#log_timezone = unknown # actually, defaults to TZ environment
# setting
#------------------------------------------------------------------------------
# RUNTIME STATISTICS
#------------------------------------------------------------------------------
# - Query/Index Statistics Collector -
#track_activities = on
#track_counts = on
#update_process_title = on
# - 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 that time.
#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_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 = 20 # default vacuum cost delay for
# autovacuum, -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
#session_replication_role = 'origin'
#statement_timeout = 0 # 0 is disabled
#vacuum_freeze_min_age = 100000000
#xmlbinary = 'base64'
#xmloption = 'content'
# - Locale and Formatting -
datestyle = 'iso, dmy'
#timezone = unknown # actually, defaults to TZ 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 2
#client_encoding = sql_ascii # actually, defaults to database
# encoding
# These settings are initialized by initdb, but they can be changed.
lc_messages = 'English_Canada' # locale for system error message
# strings
lc_monetary = 'English_Canada' # locale for monetary formatting
lc_numeric = 'English_Canada' # locale for number formatting
lc_time = 'English_Canada' # locale for time formatting
# default configuration for text search
default_text_search_config = 'pg_catalog.english'
# - Other Defaults -
#explain_pretty_print = on
#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.
#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------
# - Previous PostgreSQL Versions -
add_missing_from = on
#array_nulls = on
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = on
#regex_flavor = advanced # advanced, extended, or basic
#sql_inheritance = on
#standard_conforming_strings = off
#synchronize_seqscans = on
# - Other Platforms and Clients -
#transform_null_equals = off
我主要是在寻找效率或明智地使用资源。我知道这取决于我打算如何使用它以及其他此类“取决于”答案。我正在寻找的是重要或常见的变量自定义；人们最常改变哪些，为什么？
谢谢！