Re: the right time to vacuum database?

On 6 5 , 9 25 , a(dot)(dot)(dot)(at)crankycanuck(dot)ca (Andrew Sullivan) wrote:
> On Tue, Jun 05, 2007 at 03:33:09AM -0700, Charles.Hou wrote:
> > how can i know that it's the time to vacuumdb? i set the crontab to
> > vacuumdb 3 times in one day. because my database size increase from
> > 440MB to 460MB in 8 hours.
>
> You haven't told us enough. What's the churn on the database, to
> begin with? That's only 20M. If you replace approximately 20M in 8
> hours, then it might be that the FSM is working perfectly, and this
> is the overhead that is reasonable to keep around to allow your
> database to work perfectly.
>
> Also, have you looked into autovacuum? It might take some of the
> guesswork out of this.
>
> Finally, I expect that most of your churn is in particular tables.
> Those are the ones you want to vacuum frequently. The rest of them
> aren't that interesting. The way to learn about this is to use
> VACUUM VERBOSE, which will give you information about how many pages
> it is recovering.
>
> A
>
> --
> Andrew Sullivan | a(dot)(dot)(dot)(at)crankycanuck(dot)ca
> "The year's penultimate month" is not in truth a good way of saying
> November.
> --H.W. Fowler
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster

the version of PostgreSQL is 8.1.3 on i686-redhat-linux-gnu,compiled
by GCC 3.4.4 (Red-Hat 3.4.4-2)
Client connected: about 100 pc, 1 pc with 1 connection at least, the
max is 4 connections
194 tables on the database, and some of the tables always executed
the update/insert command .
i also set the autovacuum to enable. today, the database size is
497MB. 497-440MB=57MB, 57 MB have been increased in 18 hours.
what's wrong with my PostgreSql Server?
postgresql.conf

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

# - Connection Settings -

#listen_addresses = 'localhost' # what IP address(es) to listen on;
listen_addresses = '*' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost', '*' = all
#port = 5432
max_connections = 1000
# note: increasing max_connections costs ~400 bytes of shared memory
per
# connection slot, plus lock space (see max_locks_per_transaction).
You
# might also need to raise shared_buffers to support more connections.
superuser_reserved_connections = 2
#unix_socket_directory = ''
#unix_socket_group = ''
#unix_socket_permissions = 0777 # octal
#bonjour_name = '' # defaults to the computer name

# - Security & Authentication -

#authentication_timeout = 60 # 1-600, in seconds
#ssl = off
#password_encryption = on
#db_user_namespace = off

# Kerberos
#krb_server_keyfile = ''
#krb_srvname = 'postgres'
#krb_server_hostname = '' # empty string matches any keytab entry
#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 -

shared_buffers = 2000 # min 16 or max_connections*2, 8KB each
temp_buffers = 1000 # min 100, 8KB each
#max_prepared_transactions = 5 # can be 0 or more
# note: increasing max_prepared_transactions costs ~600 bytes of
shared memory
# per transaction slot, plus lock space (see
max_locks_per_transaction).
work_mem = 1024 # min 64, size in KB
maintenance_work_mem = 16384 # min 1024, size in KB
#max_stack_depth = 2048 # min 100, size in KB

# - Free Space Map -

#max_fsm_pages = 20000 # min max_fsm_relations*16, 6 bytes each
max_fsm_pages = 300000 # min max_fsm_relations*16, 6 bytes each
max_fsm_relations = 1000 # min 100, ~70 bytes each
#max_fsm_relations = 2000 # min 100, ~70 bytes each

# - Kernel Resource Usage -

#max_files_per_process = 1000 # min 25
#preload_libraries = ''

# - Cost-Based Vacuum Delay -

#vacuum_cost_delay = 0 # 0-1000 milliseconds
vacuum_cost_delay = 200 # 0-1000 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
vacuum_cost_page_hit = 6 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 0-10000 credits
vacuum_cost_limit = 100 # 0-10000 credits

# - Background writer -

#bgwriter_delay = 200 # 10-10000 milliseconds between rounds
#bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned/round
#bgwriter_lru_maxpages = 5 # 0-1000 buffers max written/round
#bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned/round
#bgwriter_all_maxpages = 5 # 0-1000 buffers max written/round

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

# - Settings -

#fsync = on # turns forced synchronization on or off
#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 = 8 # min 4, 8KB each
#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 = 300 # range 30-3600, in seconds
#checkpoint_warning = 30 # in seconds, 0 is off

# - Archiving -

archive_command = '' # command to use to archive a logfile
# segment
#Added, IChang, 11/28/2006 for restore
#archive_command = 'cp -f %p /home/csc/DB_HotBackup/archives/%f'

#---------------------------------------------------------------------------
# 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 = off
enable_sort = on
enable_tidscan = on

# - Planner Cost Constants -

#effective_cache_size = 1000 # typically 8KB each
effective_cache_size = 1300 # 2/3 of Ram
random_page_cost = 4 # units are one sequential page fetch
# cost
#cpu_tuple_cost = 0.01 # (same)
#cpu_index_tuple_cost = 0.001 # (same)
#cpu_operator_cost = 0.0025 # (same)

# - 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
# JOINs

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

# - Where to Log -

#log_destination = 'syslog' # Valid values are combinations of
# stderr, syslog and eventlog,
# depending on platform.

# This is used when logging to stderr:
redirect_stderr = on # Enable capturing of stderr into log
#redirect_stderr = off # Enable capturing of stderr into log
# files

# These are only used if redirect_stderr 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.
log_filename = 'postgresql-%a.log' # Log file name pattern.
# Can include strftime() escapes
log_truncate_on_rotation = on # If on, any 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 = 1440 # Automatic rotation of logfiles will
# happen after so many minutes. 0 to
# disable.
log_rotation_size = 0 # Automatic rotation of logfiles will
# happen after so many kilobytes of 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 = panic # Values in order of increasing
severity:
# debug5
# debug4
# debug3
# debug2
# debug1
# info
# notice
# warning
# error
# panic(off)

#log_min_duration_statement = -1 # -1 is disabled, 0 logs all
statements
# and their durations, in milliseconds.

#silent_mode = on # DO NOT USE without syslog or
# redirect_stderr

# - What to Log -

#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = off
log_connections = off
#log_connections = on
log_disconnections = off
#log_disconnections = on
#log_duration = off
log_duration = on
#log_line_prefix = '' # Special values:
#log_line_prefix = 'user=%u,db=%d'
log_line_prefix = '%t %p ' # Special values:
# %u = user name
# %d = database name
# %r = remote host and port
# %h = remote host
# %p = PID
# %t = timestamp (no milliseconds)
# %m = timestamp with milliseconds
# %i = command tag
# %c = session id
# %l = session line number
# %s = session start timestamp
# %x = transaction id
# %q = stop here in non-session
# processes
# %% = '%'
# e.g. '<%u%%%d> '
#log_statement = 'none' # none, mod, ddl, all
#log_statement = 'all' # none, mod, ddl, all
log_statement = 'mod' # none, mod, ddl, all
#log_hostname = off

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

# - Statistics Monitoring -

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

# - Query/Index Statistics Collector -

stats_start_collector = on
#stats_command_string = off
#stats_block_level = off
#stats_row_level = off
stats_row_level = on
#stats_reset_on_server_start = off

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

#autovacuum = off # enable autovacuum subprocess?
autovacuum = on # enable autovacuum subprocess?
autovacuum_naptime = 20 # time between autovacuum runs, in secs
#autovacuum_vacuum_threshold = 1000 # min # of tuple updates before
autovacuum_vacuum_threshold = 1 # min # of tuple updates before
# vacuum
#autovacuum_analyze_threshold = 500 # min # of tuple updates before
autovacuum_analyze_threshold = 1 # min # of tuple updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.4 # fraction of rel size before
autovacuum_vacuum_scale_factor = 0.1 # fraction of rel size before
# vacuum
autovacuum_analyze_scale_factor = 0.2 # fraction of rel size before
#autovacuum_analyze_scale_factor = 1 # fraction of rel size before
# analyze
#autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for
# autovac, -1 means use
# vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovac, -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
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#statement_timeout = 0 # 0 is disabled, in milliseconds

# - Locale and Formatting -

#datestyle = 'iso, mdy'
#timezone = unknown # actually, defaults to TZ
# environment setting
#australian_timezones = off
#extra_float_digits = 0 # min -15, max 2
#client_encoding = sql_ascii # actually, defaults to database
client_encoding = BIG5 # actually, defaults to database
# encoding

# These settings are initialized by initdb -- they might be changed
#lc_messages = 'zh_TW.big5' # locale for system error message
lc_messages = 'C' # locale for system error message
# strings
#lc_monetary = 'zh_TW.big5' # locale for monetary formatting
lc_monetary = 'C' # locale for monetary formatting
#lc_numeric = 'zh_TW.big5' # locale for number formatting
lc_numeric = 'C' # locale for number formatting
#lc_time = 'zh_TW.big5' # locale for time formatting
lc_time = 'C' # locale for time formatting

# - Other Defaults -

#explain_pretty_print = on
#dynamic_library_path = '$libdir'

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

#deadlock_timeout = 1000 # in milliseconds
#max_locks_per_transaction = 64 # min 10
# note: each lock table slot uses ~220 bytes of shared memory, and
there are
# max_locks_per_transaction * (max_connections +
max_prepared_transactions)
# lock table slots.

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

# - Previous Postgres Versions -

#add_missing_from = off
#regex_flavor = advanced # advanced, extended, or basic
#sql_inheritance = on
#default_with_oids = off
#escape_string_warning = off

# - Other Platforms & Clients -

#transform_null_equals = off

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

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