Posgres benötigt fast keinen RAM !?

Hi

Ich bin gerade von MySQL auf Postgres umgestiegen. Wir betreiben ein System das Bilder speichert und die Ablage der Bilder und deren Tags in einer DB speichert. Komplizierte Anfragen/Abläufe gibt es nicht, nur banale Suchen nach DB-Feldern. 90% sind DB-Schreibvorgänge, der Rest sind Lesenafragen.
Es wird nichts gelöscht. Datenbankgröße ist aktuell 18GB

Auf dem alten XP 32bit System belegte MySQL nach einigen Tagen etwa 1,8GB im RAM (mehr waren nicht gestattet).
Postgres hingegen kommt auf maximal 30-60MB nach mehreren Tagen als ob es überhaupt kein RAM benötigt!?
Das aktuelle System ist Windows Server 2012 R2 32GB Ram, die Datenbank ist auf einer SSD gespeichert.#

Kann es sein das Postgres aufgrund der SSD eine caching nicht für notwendig hält?

Die Postgres.conf sieht so aus:

# -----------------------------
# 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 = ''			# write an extra PID file
					# (change requires restart)


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

# - Connection Settings -

listen_addresses = '*'		# what IP address(es) to listen on;
					# comma-separated list of addresses;
					# defaults to 'localhost'; use '*' for 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_directories = ''	# comma-separated list of directories
					# (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 = off				# (change requires restart)
#ssl_ciphers = 'DEFAULT:!LOW:!EXP:!MD5:@STRENGTH'	# allowed SSL ciphers
					# (change requires restart)
#ssl_renegotiation_limit = 512MB	# amount of data between renegotiations
#ssl_cert_file = 'server.crt'		# (change requires restart)
#ssl_key_file = 'server.key'		# (change requires restart)
#ssl_ca_file = ''			# (change requires restart)
#ssl_crl_file = ''			# (change requires restart)
#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 = 256MB			# 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

# - Disk -

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

# - 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 = 0			# 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 -

#wal_level = minimal			# minimal, archive, or hot_standby
					# (change requires restart)
#fsync = on				# turns forced synchronization on or off
#synchronous_commit = on		# synchronization level;
					# off, local, remote_write, or on
#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
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 = 10		# in logfile segments, min 1, 16MB each
checkpoint_timeout = 5min		# range 30s-1h
checkpoint_completion_target = 0.9	# 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
				# placeholders: %p = path of file to archive
				#               %f = file name only
				# e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'
#archive_timeout = 0		# force a logfile segment switch after this
				# number of seconds; 0 disables


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

# - Sending Server(s) -

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

#max_wal_senders = 0		# max number of walsender processes
				# (change requires restart)
#wal_keep_segments = 0		# in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s	# in milliseconds; 0 disables

# - Master Server -

# These settings are ignored on a standby server.

#synchronous_standby_names = ''	# standby servers that provide sync rep
				# 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 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
#wal_receiver_timeout = 60s		# time that receiver waits for
					# communication from master
					# in milliseconds; 0 disables


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

# - Planner Method Configuration -

#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_indexonlyscan = on
#enable_material = 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 = 10GB

# - 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
#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_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'

# This is only relevant when logging to eventlog (win32):
#event_source = 'PostgreSQL'

# - 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)

#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_error_verbosity = default		# terse, default, or verbose messages
#log_hostname = off
log_line_prefix = '%t '			# 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
#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 = 'CET'


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

# - Query/Index Statistics Collector -

#track_activities = on
#track_counts = on
#track_io_timing = off
#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
#lock_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 = 'CET'
#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.
lc_messages = 'German_Germany.1252'			# locale for system error message
					# strings
lc_monetary = 'German_Germany.1252'			# locale for monetary formatting
lc_numeric = 'German_Germany.1252'			# locale for number formatting
lc_time = 'German_Germany.1252'				# locale for time formatting

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

# - 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?


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

# These options allow settings to be loaded from files other than the
# default postgresql.conf.

#include_dir = 'conf.d'			# include files ending in '.conf' from
					# directory 'conf.d'
#include_if_exists = 'exists.conf'	# include file only if it exists
#include = 'special.conf'		# include file


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

# Add settings for extensions here

Aufgrund shared_buffers=256MB würde ich hier Speicherverbraucht in etwa dieser Größenordnung vermuten.
Neustart nach Änderung vergessen? Wen es ein dedizierter Server nur für PG ist, dann könntest Du das auf locker 6-8GB setzen.
work_mem könnte auch höher sein. Aber das ist dann feintuning.

Bei SSD könntest Du random_page_cost auf etwas über 1 setzen, 4 ist da zu hoch (bei guten SSD-Zeugs).

Mhh ok

Ich hatte das in den Postgres Wikis so verstanden dass “shared_buffers” auf Windows Servern nicht über 512MB gehen soll/darf und man stattdessen “effective_cache_size” auf mehrere GB setzen soll? Ich kann 17GB Ram für Postgres bereitstellen auf dem Server.

PS: nein dienst bzw server restart hatte ich nicht vergessen.

Vielleicht hast nicht die richtige config angepaßt? Was sagt “show config_file;” innerhalb von psql?

Was jetzt Besonderheiten unter so exotischen Betriebssystemen angeht fehlen mir die Erfahrungen.

Hi

Also mit der Eingabe show config_file in der Shell kommt nicht als output (ja ich bin admin :slight_smile: ).
Ich benutze die posgresql.conf unter \Data\postgresql.conf - ich denke dass ist die richtige. Einmal hatte ich da nen Tippfehler drinnen und der Server startete nicht - ich denke dass spricht für die richtige config Datei :slight_smile:

Aber hey Windows Server 2012 als exotische OS !?

Dann machst Du was falsch.

test=*# show config_file;
              config_file
---------------------------------------
 /usr/local/pgsql/data/postgresql.conf
(1 row)



Aber hey Windows Server 2012 als exotische OS !?

Ja. Wo kann man das downloaden?

Hier: http://technet.microsoft.com/de-de/evalcenter/dn205286.aspx :wink:

So, jetzt aber zurück zu eurer Problemlöserei :wink:

cu tb

oops Tippfehler:

Outpout: E:\PostgreSQl-Data\postgresql.conf

also ändere ich die richtige

Das kannst nur Du prüfen. Wie hab ich Dir gesagt. PG bringt eine Default-Config mit, die bei initdb in das data-dir kopiert wird und die ist dann die genutzte. Es sei denn, durch weitere Parameter wird eine andere zugewiesen.

So was würde ich doch als noob user nie machen bei dem einfachen projekt was ich da betreibe :slight_smile: - es gibt nur die Eine.

Um noch mal auf die Frage zurückzukommen: PG nutzt das, was ihm zugeteilt wird. Das ist insbesondere shared_buffers und work_mem. PG startet je Connection einen neuen Prozess, möglicherweise hast Du auch die Speichernutzung falsch ermittelt. PG kann, wenn ihm nicht viel gegeben wird, auch mit wenig RAM recht flott laufen, dann kümmert sich das OS drum, den RAM als Cache zu nutzen.

PG weiß nicht, ob das nun sich drehende Metallplatten sind, wo es drauf speichert, oder SSD’s oder ob da jemand das erst in Stein meiseln muß - es wartet auf das Ende von fsync() und vertraut dann darauf, daß alles schon korrekt ist.

Natürlich profitiert es von viel RAM, wenn PG es direkt als shared_buffer und/oder work_mem nutzen kann. Die anderen Paremeter sind erst einmal nicht so entscheidend. Bei SSD kann, muß man aber nicht, den genannten Parameter anpassen. Es wird dann Index-Scans eher bevorzugen.

Ok alles klar.

Kann unter Windows Server shared_buffers auf mehrere GB setzen oder führt das zu abstürzen bzw bringt es keinen Perofrmancegewinn?

IIRC stammt dieser Hinweis noch aus Zeiten, von PG auf manchen exotischen Systemen nur als 32bit - Version verfügbar war. Hast Du denn ein 64bit-OS?
Und ist PG auch 64bit?

Jo Win Server 2012 64bit R2 PGSQL ist auch 64it

Dann kanst auch mehr als 1,2 oder 4GB nehmen, ich wüßte keinen Grund, der dagegen spricht. Aber shared_buffers ist nicht alles, je nach Abfrage ist work_mem auch wichtig. Und immer schon Explain nutzen.