Re: Is my database now too big?

Scott Marlowe wrote:
> On 10/7/07, Darren Reed <darrenr@fastmail.net> wrote:
> > Scott Marlowe wrote:
> > > ...
> > >
> > > Any reasonably modern version of pgsql should simply stop accepting
> > > requests rather than suffering loss due to txid wraparound.So,I can
> > > think of two possibilities here. Bad hardware or operator error.
> > >
> > > Assuming you've checked out your machine thoroughly for bad hardware,
> > > I can see a scenario where one does something like:
> > >
> > > begin;
> > > create table xyz;
> > > load 10,000,000 rows
> > > manipulate rows
> > > shutdown db without committing
> > > start database
> > > voila, table xyz is gone, and rightly so.
> > >
> > > Got more detailed info on what you're doing?
> >
> > That does describe what was happening (I haven't used BEGIN/COMMIT.)
>
> then it isn't the same thing.  If you did a begin, then did everything
> else without commit, the table would rightly disappear.
>

Right, I'm with you on that.
A few days ago I did:
pg_dumpall > foo
What I was doing yesterday was:
rm -rf /data/db/*
initdb -D /data/db
start
psql < foo
run for some period
stop
reboot
start
...tables have gone but disk space is still in use.
I dont know if it was during the period of running that the
database got corrupted (interrupted insert/update/query?)
or what happened.


> > Nothing very special, I thought...
> >
> > But, doing "SELECT * FROM ifl LIMIT 1;" causes postgres to grow its
> > process to 2GB and then die because the OS ran out of swap!
>
> I doubt that exact query is causing the db to run out of memory,
> unless ifl is a complex view or something.
>
> Can you be more specific on what exact query causes the problem to show up?
>

It turned out that _any_ query on that table caused the problem to show up.

I couldn't even do "DROP TABLE ifl;" without postgres growing until it
ran out of memory.

So in the end, I wiped it clean and reloaded the data - this time
bounding all of the
work with BEGIN/COMMIT.  So far things are looking better.  All of the
data I've
been building the tables with is elsewhere, so I can reconstruct it.
Maybe adding
BEGIN/COMMIT makes no difference to not using them before, but I'm curious
to see if it does.  Ideally I'd like to get to a place where I don't
need to use vacuum
at all.

> > Actually, this is a table that sees a lot of INSERT/DELETE (it's a place to
> > store work to be done and bits get removed when completed) and I haven't
> > been using BEGIN/COMMIT.  This is how postgres currently handles it:
> >
> > LOG:  database system was not properly shut down; automatic recovery in
> > progress
> > LOG:  record with zero length at 0/891157C8
> > LOG:  redo is not required
> > LOG:  database system is ready
> > LOG:  transaction ID wrap limit is 2147484146, limited by database
> > "postgres"
> > LOG:  unexpected EOF on client connection
> > LOG:  server process (PID 7212) was terminated by signal 9
> > LOG:  terminating any other active server processes
> > WARNING:  terminating connection because of crash of another server process
>
> Looks like some query is running the server out of memory.  Normally,
> postgresql will spill to disk if it needs more memory, unless it's
> miconfigured.
>

Yes.  I tried increasing the swap space but that just meant it grew
larger...from limit:
datasize     3145728 kbytes

This is from NetBSD 4.99.  I ended up running with 3.5GB of SWAP and
1.5GB of RAM.


> > I'm modifying the work to use BEGIN/COMMIT, but the ifl table worries me...
> > I can't seem to do anything with it that doesn't cause postgres to crap
> > out ;(
>
> begin/commit ain't the problem here.  Looks like you've either got
> pgsql set to use too much memory or it's choosing a bad plan where it
> thinks something will fit in memory but it won't.
>

I have no other problems with any of the other tables and it is only a
small table (at the time
it should have had less than 5000 rows.)

> Have you been analyzing your data before you start working on it?
>

No.

> Can we see your postgresql.conf file?
>

Sure, I've attached it.
I've also run with the "default" .conf file without tuning it (down.)

Darren

# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
#   name = value
#
# (The '=' is optional.) White space may be used. Comments are introduced
# with '#' anywhere on a line. The complete list of option names and
# allowed values can be found in the PostgreSQL documentation. The
# commented-out settings shown in this file represent the default values.
#
# Please note that re-commenting a setting is NOT sufficient to revert it
# to the default value, unless you restart the postmaster.
#
# Any option can also be given as a command line switch to the
# postmaster, e.g. 'postmaster -c log_connections=on'. Some options
# can be changed at run-time with the 'SET' SQL command.
#
# This file is read on postmaster startup and when the postmaster
# receives a SIGHUP. If you edit the file on a running system, you have
# to SIGHUP the postmaster for the changes to take effect, or use
# "pg_ctl reload". Some settings, such as listen_addresses, require
# a postmaster shutdown and restart to take effect.


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

# The default values of these variables are driven from the -D command line
# switch or PGDATA environment variable, represented here as ConfigDir.

#data_directory = 'ConfigDir'        # use data in another directory
#hba_file = 'ConfigDir/pg_hba.conf'    # host-based authentication file
#ident_file = 'ConfigDir/pg_ident.conf'    # IDENT configuration file

# If external_pid_file is not explicitly set, no extra pid file is written.
#external_pid_file = '(none)'        # write an extra pid file


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

# - Connection Settings -

#listen_addresses = 'localhost'        # what IP address(es) to listen on;
                    # comma-separated list of addresses;
                    # defaults to 'localhost', '*' = all
#port = 5432
max_connections = 15
# 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 = 200            # 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 = 4096            # min 64, size in KB
maintenance_work_mem = 8192        # min 1024, size in KB
max_stack_depth = 400            # min 100, size in KB

# - Free Space Map -

max_fsm_pages = 20000        # min max_fsm_relations*16, 6 bytes each
max_fsm_relations = 200        # min 100, ~70 bytes each

# - Kernel Resource Usage -

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

# - 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        # 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


#---------------------------------------------------------------------------
# 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 -

effective_cache_size = 1000        # typically 8KB each
#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 = 'stderr'        # Valid values are combinations of
                    # stderr, syslog and eventlog,
                    # depending on platform.

# This is used when logging to stderr:
#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.
                    # Can include strftime() escapes
#log_truncate_on_rotation = off # 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 = 10240        # 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 = off            # 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_disconnections = off
#log_duration = off
#log_line_prefix = ''            # 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_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_reset_on_server_start = off


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

#autovacuum = off            # enable autovacuum subprocess?
#autovacuum_naptime = 60        # time between autovacuum runs, in secs
#autovacuum_vacuum_threshold = 1000    # min # of tuple updates before
                    # vacuum
#autovacuum_analyze_threshold = 500    # min # of tuple updates before
                    # analyze
#autovacuum_vacuum_scale_factor = 0.4    # fraction of rel size before
                    # vacuum
#autovacuum_analyze_scale_factor = 0.2    # 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
                    # encoding

# These settings are initialized by initdb -- they might 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

# - 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