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Bonjour,
J'ai fait une reprise de données sur un Datawarehouse et la volumétrie a explosé ! Je suis passé de 670 Go à 1,4 To ! 
Non je n'ai pas fait d'INSERT ! 
J'ai bien fait uniquement des UPDATE.
Cette explosion de la volumétrie apparaît principalement sur 3 tables :
-- Table 1
-- Prod : 54 GB + 36 GB
-- Recette : 104 GB + 92 GB-- Table 2
-- Prod : 111 GB + 54 GB
-- Recette : 248 GB + 108 GB-- Table 3
-- Prod : 126 GB + 72 GB
-- Recette : 349 GB + 253 GB
Je pensais faire comme ça pour résoudre ce problème, mais rien que sur la plus petite table au bout de 3 heures le VACUUM FULL n'est toujours pas fini !!
DROP INDEX ...;
vacuum full ...;
CREATE INDEX ...;
vacuum analyze ...;Une autre idée ? Est-ce qu'un paramétrage particulier de PostgreSQL.conf aiderait ?
Gôm
Dernière modification par gom (12/02/2013 19:31:48)
Hors ligne
Pas très étonnant que la volumétrie augmente fortement avec un UPDATE, vu qu'un UPDATE est en gros un DELETE de l'ancienne ligne et un INSERT de la nouvelle. Surtout un UPDATE massif. Quant au VACUUM FULL, oui, ça prend du temps. Il s'agit de réécrire la table complète. Suivant la version de PostgreSQL, ça sera plus ou moins lent mais clairement, c'est pas une opération rapide. Il peut être plus intéressant de recréer la table (style INSERT INTO nouvelle_table SELECT * FROM ancienne_table).
Guillaume.
Hors ligne
Que pensez-vous de ça :
CREATE TABLE nouvelle_table ...;
COPY ancienne_table TO '/var/lib/postgresql/main/base/fic_nouvelle_table.copy';
COPY nouvelle_table FROM '/var/lib/postgresql/main/base/fic_nouvelle_table.copy';
DROP TABLE ancienne_table;
ALTER TABLE nouvelle_table RENAME TO ancienne_table;
CREATE INDEX idx_toto ON ancienne_table ...;Gôm
Dernière modification par gom (13/02/2013 16:30:33)
Hors ligne
À la place des deux COPY, j'aurais fait un "INSERT INTO nouvelle_table SELECT * FROM ancienne_table".
Guillaume.
Hors ligne
C'est noté, merci.
Je vais faire ça pour les autres tables. Pour info, cela a duré 1h45 (sans la création des Index) pour la table de 54 Go (qui faisait 104 Go après les UPDATE).
Gôm
Hors ligne
Bonjour,
J'ai à nouveau les mêmes UPDATE à faire et je voudrais avoir votre avis pour savoir si tout ça ne peut pas être amélioré !
Mon idée serait de réécrire toutes mes requêtes UPDATE par des "INSERT INTO nouvelle_table SELECT * FROM ancienne_table WHERE ..." => ainsi je n'aurai plus de tables 2 fois plus volumineuses (je n'aurai qu'à supprimer les anciennes_tables), mais dans tous les cas je suis obligé de recalculer tous les Index concernés par ces tables.
Concernant la recréation de ces Index (par DROP INDEX et CREATE INDEX, car j'ai besoin de certains Index lors de mes UPDATE) ... c'est là que vous intervenez ! 
Ne pensez-vous pas qu'il est possible de changer provisoirement le paramétrage du postgresql.conf (version PostgreSQL Linux 8.4) afin d'accélérer la recréation de ces Index ?
# -----------------------------
# 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 = 'ConfigDir' # use data in another directory
# (change requires restart)
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
# (change requires restart)
#ident_file = 'ConfigDir/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 = '(none)' # write an extra PID file
# (change requires restart)#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------# - Connection Settings -
#listen_addresses = 'localhost' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost', '*' = all
# (change requires restart)
#port = 5432 # (change requires restart)
max_connections = 100 # (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 = '' # (change requires restart)
#unix_socket_group = '' # (change requires restart)
#unix_socket_permissions = 0777 # begin with 0 to use octal notation
# (change requires restart)
#bonjour_name = '' # defaults to the computer name
# (change requires restart)# - Security and Authentication -
#authentication_timeout = 1min # 1s-600s
#ssl = off # (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 -
shared_buffers = 32MB # 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.
#work_mem = 1MB # min 64kB
#maintenance_work_mem = 16MB # 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 -
#effective_io_concurrency = 1 # 1-1000. 0 disables prefetching
#------------------------------------------------------------------------------
# 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 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#------------------------------------------------------------------------------
# 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 = 128MB# - 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 = 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
#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-%a.log' # log file name pattern,
# can include strftime() escapes
log_truncate_on_rotation = on # 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 disables.
log_rotation_size = 0 # 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'#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_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 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
#log_duration = off
#log_hostname = off
#log_line_prefix = '' # 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 the specified size in kilobytes;
# -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
#track_functions = none # none, pl, all
#track_activity_query_size = 1024
#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
#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 = '"$user",public' # schema names
#default_tablespace = '' # a tablespace name, '' uses the default
#temp_tablespaces = '' # a list of tablespace names, '' uses
# only default tablespace
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#session_replication_role = 'origin'
#statement_timeout = 0 # in milliseconds, 0 is disabled
#vacuum_freeze_min_age = 50000000
#vacuum_freeze_table_age = 150000000
#xmlbinary = 'base64'
#xmloption = 'content'# - Locale and Formatting -
datestyle = 'iso, dmy'
#intervalstyle = 'postgres'
#timezone = unknown # actually, defaults to TZ environment
# setting
#timezone_abbreviations = 'Default' # Select the set of available time zone
# abbreviations. Currently, there are
# Default
# Australia
# India
# You can create your own file in
# share/timezonesets/.
#extra_float_digits = 0 # min -15, max 2
#client_encoding = sql_ascii # actually, defaults to database
# encoding# These settings are initialized by initdb, but they can be changed.
lc_messages = 'fr_FR.UTF-8' # locale for system error message
# strings
lc_monetary = 'fr_FR.UTF-8' # locale for monetary formatting
lc_numeric = 'fr_FR.UTF-8' # locale for number formatting
lc_time = 'fr_FR.UTF-8' # locale for time formatting# default configuration for text search
default_text_search_config = 'pg_catalog.french'# - Other Defaults -
#dynamic_library_path = '$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.#------------------------------------------------------------------------------
# VERSION/PLATFORM COMPATIBILITY
#------------------------------------------------------------------------------# - Previous PostgreSQL Versions -
#add_missing_from = off
#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
#------------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#------------------------------------------------------------------------------#custom_variable_classes = '' # list of custom variable class names
#------------------------------------------------------------------------------
# Modif Prod
#------------------------------------------------------------------------------# - Connexions -
listen_addresses = '*'# - Memoire -
shared_buffers = 2GB
wal_buffers = 8MB
work_mem = 300MB
maintenance_work_mem = 1GB# - Journaux de transactions -
checkpoint_segments = 50
checkpoint_timeout = 10min
checkpoint_completion_target = 0.9# - Optimiseur -
effective_cache_size = 5376MB
random_page_cost = 2.0# - Traces -
log_destination = 'csvlog'
log_filename = 'postgresql-%Y-%m-%d.log'
log_truncate_on_rotation = off
log_line_prefix = '%t [%p]: [%l-1] '
lc_messages = 'C'
log_checkpoints = on
log_lock_waits = on
log_temp_files = 0
log_autovacuum_min_duration = 0# - Specifique restauration -
#fsync = off
#checkpoint_segments = 200
#checkpoint_timeout = 20min
Gôm
Dernière modification par gom (28/02/2013 10:56:35)
Hors ligne
Certains paramètres à changer demanderaient de redémarrer PostgreSQL, donc ça m'étonnerait que ça vous intéresse. Le seul paramètre intéressant dans votre cas est certainement maintenance_work_mem.
Guillaume.
Hors ligne
Les UPDATE demandent plusieurs jours d'exécution donc non je ne suis pas à quelques redémarrages près !
Pourriez vous me donner une valeur pour maintenance_work_mem ?
Hors ligne
Les 1GB de maintenance_work_mem ne sont pas suffisants ? J'ai 16 Go de RAM sur le serveur.
Hors ligne
Vous pouvez aller jusqu'à 2 Go pour le maintenance_work_mem. J'augmenterais bien le wal_buffers. Je désactiverais synchronous_commit. Et j'augmenterais les checkpoint_*.
Guillaume.
Hors ligne
Quelque chose comme ça ?
# - Specifique UPDATE massif -
maintenance_work_mem = 2GB
wal_buffers = 32MB
fsync = off
synchronous_commit = off
checkpoint_segments = 200
checkpoint_timeout = 1h
checkpoint_warning = 0Hors ligne
Le checkpoint_timeout est beaucoup trop élevé, ça sera certainement contre productif. Le fsync est dangereux, il ne faut vraiment pas oublier de le réactiver une fois l'import fini.
Julien.
https://rjuju.github.io/
Hors ligne
Ok ok je vais rester raisonnable! 
# - Specifique UPDATE massif -
maintenance_work_mem = 2GB
wal_buffers = 32MB
fsync = on
synchronous_commit = off
checkpoint_segments = 200
checkpoint_timeout = 20min
checkpoint_warning = 0Hors ligne
Bon apparemment fsync à OFF est vraiment un bon moyen de gagner en performance : http://www.postgresql.org/docs/8.4/stat … #GUC-FSYNC
# - Specifique UPDATE massif -
maintenance_work_mem = 2GB
wal_buffers = 32MB
fsync = off
synchronous_commit = off
checkpoint_segments = 200
checkpoint_timeout = 20min
checkpoint_warning = 0Je vais donc prendre le risque. Je m'assurerai que personne d'autre n'utilisera PostgreSQL en même temps que moi et surtout je veillerai à remettre le paramétrage habituel une fois mes UPDATE passés.
Dernière modification par gom (15/03/2013 00:27:30)
Hors ligne
Il y a quelques cas où il est possible de mettre fsync à off mais vraiment pas ici. En cas de crash, assurez-vous d'avoir une sauvegarde car c'est une corruption garantie de l'instance.
Sans compter que synchronous_commit à off fera déjà tout le boulot d'optimisation sans les désagréments.
Guillaume.
Hors ligne
Le mieux c'est d'écouter les experts parait-il ! Merci pour tout encore une fois !
# - Specifique UPDATE massif -
maintenance_work_mem = 2GB
wal_buffers = 32MB
#fsync = on
synchronous_commit = off
checkpoint_segments = 200
checkpoint_timeout = 20min
checkpoint_warning = 0Hors ligne
Un redémarrage du serveur est-il obligatoire suite à ce changement de paramétrage ? Un simple RELOAD suffit peut-être ?
Hors ligne
Hors ligne
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