Ok.
Query
EXPLAIN
ANALYZE
select
to_char(data_encerramento,'mm/yyyy') as opcoes_mes,
to_char(data_encerramento,'yyyy-mm') as ordem
from detalhamento_bas
where
to_char( data_encerramento ,'yyyy-mm')
between '2006-12' and '2007-01'
GROUP BY opcoes_mes, ordem
ORDER BY ordem DESC
QUERY RESULT
QUERY PLAN
Sort (cost=11449.37..11449.40 rows=119 width=8) (actual
time=14431.537..14431.538 rows=2 loops=1)
Sort Key: to_char(data_encerramento, 'yyyy-mm'::text)
-> HashAggregate (cost=11448.79..11448.96 rows=119 width=8) (actual
time=14431.521..14431.523 rows=2 loops=1)
-> Index Scan using detalhamento_bas_idx3003 on detalhamento_bas
(cost=0.00..11442.95 rows=11679 width=8) (actual time=0.135..12719.155
rows=2335819 loops=1)
Index Cond: ((to_char(data_encerramento, 'yyyy-mm'::text) >=
'2006-12'::text) AND (to_char(data_encerramento, 'yyyy-mm'::text) <=
'2007-01'::text))
Total runtime: 14431.605 ms
SERVER
DELL PowerEdge 2950
XEON Quad-Core 3.0Ghz
4Gb RAM
Linux CentOS 5.0 64-bits
Postgres 8.1.4
Postgresql.conf
# -----------------------------
# 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 = '*' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost', '*' = all
#port = 5432
max_connections = 10
# 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 = 50000 # 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 = 3145728 # min 64, size in KB
maintenance_work_mem = 4194304 # min 1024, size in KB
max_stack_depth = 2048 # min 100, size in KB
# - Free Space Map -
max_fsm_pages = 208000 # min max_fsm_relations*16, 6 bytes
each
max_fsm_relations = 10000 # min 100, ~70 bytes each
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
#preload_libraries = ''
# - Cost-Based Vacuum Delay -
vacuum_cost_delay = 50 # 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 = 20.0 # 0-100% of LRU buffers
scanned/round
bgwriter_lru_maxpages = 100 # 0-1000 buffers max written/round
bgwriter_all_percent = 3 # 0-100% of all buffers
scanned/round
bgwriter_all_maxpages = 600 # 0-1000 buffers max written/round
#---------------------------------------------------------------------------
# WRITE AHEAD LOG
#---------------------------------------------------------------------------
# - Settings -
fsync = off # 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 = off # recover from partial page writes
wal_buffers = 2300 # min 4, 8KB each
commit_delay = 10 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000
# - Checkpoints -
checkpoint_segments = 256 # in logfile segments, min 1, 16MB
each
checkpoint_timeout = 300 # range 30-3600, in seconds
checkpoint_warning = 99 # 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 = 41943040 # typically 8KB each
random_page_cost = 1 # units are one sequential page
fetch
# cost
cpu_tuple_cost = 0.001 # (same)
cpu_index_tuple_cost = 0.0005 # (same)
cpu_operator_cost = 0.00025 # (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 = on
#from_collapse_limit = 8
join_collapse_limit = 1 # 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 = on # 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-%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 = 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 = off
#stats_command_string = off
#stats_block_level = off
#stats_row_level = off
#stats_reset_on_server_start = off
#---------------------------------------------------------------------------
# AUTOVACUUM PARAMETERS
#---------------------------------------------------------------------------
autovacuum = on # 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 = '$user,public' # schema names
#default_tablespace = '' # a tablespace name, '' uses
# the default
#check_function_bodies = on
default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#statement_timeout = 0 # 0 is disabled, in milliseconds
# - Locale and Formatting -
datestyle = 'iso, dmy'
#timezone = unknown # actually, defaults to TZ
# environment setting
#australian_timezones = off
#extra_float_digits = 0 # min -15, max 2
client_encoding = LATIN1 # actually, defaults to database
# encoding
# These settings are initialized by initdb -- they might be changed
lc_messages = 'pt_BR.ISO-8859-1' # locale for system
error message
# strings
lc_monetary = 'pt_BR.ISO-8859-1' # locale for
monetary formatting
lc_numeric = 'pt_BR.ISO-8859-1' # locale for number
formatting
lc_time = 'pt_BR.ISO-8859-1' # locale for time
formatting
# - Other Defaults -
#explain_pretty_print = on
#dynamic_library_path = '$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
#backslash_quote = safe_encoding # on, off, or safe_encoding
#default_with_oids = off
#escape_string_warning = off
#regex_flavor = advanced # advanced, extended, or basic
#sql_inheritance = on
# - Other Platforms & Clients -
#transform_null_equals = off
#---------------------------------------------------------------------------
# CUSTOMIZED OPTIONS
#---------------------------------------------------------------------------
#custom_variable_classes = '' # list of custom variable class
names
-----Mensagem original-----
De: Craig James [mailto:craig_james@xxxxxxxxxxxxxx]
Enviada em: sábado, 28 de julho de 2007 16:59
Para: Bruno Rodrigues Siqueira; pgsql-performance@xxxxxxxxxxxxxx
Assunto: Re: select on 1milion register = 6s
Bruno Rodrigues Siqueira wrote:
> Who can help me? My SELECT in a base with 1 milion register,
> using expression index = 6seconds?
Run your query using
EXPLAIN ANALYZE SELECT ... your query ...
and then post the results to this newsgroup. Nobody can help until they see
the results of EXPLAIN ANALYZE. Also, include all other relevant
information, such as Postgres version, operating system, amount of memory,
and any changes you have made to the Postgres configuration file.
Craig
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
