Re: out of memory - no sort

Hello

if table is large, then client can raise this exception too

try to set FETCH_COUNT to 1000

http://www.postgresql.org/docs/8.4/interactive/app-psql.html

Regards

Pavel Stehule

2011/8/30 Don <Donald(dot)Laurine(at)noaa(dot)gov>:
> I am trying a simple access of a table and get an out of memory error.  How
> do I avoid this issue.  It seems I have some configuration set wrong.
>
> Our system has 24GB of memory and is dedicated to the postgres database.
>
> Back ground information
>
> aquarec=> explain analyze verbose select * from ens_memb;
>                                                         QUERY
> PLAN
> --------------------------------------------------------------------------------------------------------------------------
>  Seq Scan on ens_memb  (cost=0.00..719893.12 rows=32216212 width=62) (actual
> time=4.954..37513.377 rows=32216154 loops=1)
>    Output: id, shefpc, bwmon, ewmon, pb, tb, cdate, vdate, source, tyr, val
>  Total runtime: 39588.386 ms
>
>
> #------------------------------------------------------------------------------
> # RESOURCE USAGE (except WAL)
> #------------------------------------------------------------------------------
>
> # - Memory -
>
> shared_buffers = 6144MB                 # min 128kB
>                                         # (change requires restart)
> #temp_buffers = 8MB                     # min 800kB
> max_prepared_transactions = 5           # 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 = 48MB                         # min 64kB
> maintenance_work_mem = 256MB            # 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 = 8MB                       # 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 = 32                # 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 = 3.0                  # 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 = 12288MB
>
> # - 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
>