PostgreSQL 在 PHP 上的简单连接和查询稍慢

Question

在 PHP 5.4.1 中，我使用本机 PostgreSQL 驱动程序连接到 SQL 服务器。即使我尝试 PDO 方式也是一样的。这里只有一个例外。如果我使用 pg_pconnect (persistent)，它会像我预期的那样非常快。

我从 PHP 到 PostgreSQL 的连接很慢。另外，一些查询也很慢。

例如，请看一下这张表。

id  type    active  serverip
1   1   0   127.0.0.1
2   10  1   127.0.0.1
3   4   1   127.0.0.1
4   7   1   127.0.0.1
5   13  1   127.0.0.1
6   2   1   127.0.0.1
7   11  1   127.0.0.1
8   6   1   127.0.0.1
9   9   1   127.0.0.1
10  3   0   192.168.1.202
11  5   1   127.0.0.1
12  8   1   127.0.0.1
13  12  1   127.0.0.1
14  14  1   127.0.0.1

我的查询是select * from mytable order by id desc。所以，

此表在id 上有索引和主键。此表在 MySQL 5.5.23 和 PostgreSQL 9.1.3 中相同 (1:1)

MySQL 连接这个数据库并在0.0019 sec. 中读取这个表（整个数据）但是PostgreSQL 需要0.0069 sec。这可能看起来像往常一样，但如果 MySQL 可以非常快地做到这一点，为什么不 PostgreSQL 呢？

在我的大桌子上，它需要的时间比这长。在大表中 MySQL 连接并在 0.09601 sec, 中获取 PostgreSQL 连接并在 0.11260 秒 0.14201 sec. 中获取它（现已测试）

如您所见，在这个非常简单的数据库表中，PostgreSQL 简直太慢了。这是我的 postgresql.conf 文件：

    listen_addresses = '*'      # 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 = off              # advertise server via Bonjour
                    # (change requires restart)
#bonjour_name = ''          # defaults to the computer name
                    # (change requires restart)

# - Security and Authentication -

authentication_timeout = 20s        # 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 = 1GB            # min 128kB
                    # (change requires restart)
temp_buffers = 16MB         # 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 = 64MB             # min 64kB
maintenance_work_mem = 32MB     # min 1MB
max_stack_depth = 8MB           # 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 = 100      # 0-10000 credits
vacuum_cost_page_miss = 100     # 0-10000 credits
vacuum_cost_page_dirty = 200        # 0-10000 credits
vacuum_cost_limit = 2000        # 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; on, off, or local
#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 = 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


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

# - Master Server -

# These settings are ignored on a standby server

#max_wal_senders = 0        # max number of walsender processes
                # (change requires restart)
#wal_sender_delay = 1s      # walsender cycle time, 1-10000 milliseconds
#wal_keep_segments = 0      # in logfile segments, 16MB each; 0 disables
#vacuum_defer_cleanup_age = 0   # number of xacts by which cleanup is delayed
#replication_timeout = 60s  # in milliseconds; 0 disables
#synchronous_standby_names = '' # standby servers that provide sync rep
                # comma-separated list of application_name
                # from standby(s); '*' = all

# - 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


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

# - Planner Method Configuration -

enable_bitmapscan = on
enable_hashagg = on
enable_hashjoin = on
enable_indexscan = 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 = 512MB

# - 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-%a.log'  # log file name pattern,
                    # can include strftime() escapes
log_file_mode = 0777            # creation mode for log files,
                    # begin with 0 to use octal notation
log_truncate_on_rotation = on       # 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 = 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_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 = ''           # 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 = '(defaults to server 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    # (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
vacuum_freeze_min_age = 50000000
vacuum_freeze_table_age = 150000000
bytea_output = 'hex'            # hex, escape
xmlbinary = 'base64'
xmloption = 'content'

# - Locale and Formatting -

datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
#timezone = '(defaults to server 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 3
#client_encoding = sql_ascii        # actually, defaults to database
                    # encoding

# These settings are initialized by initdb, but they can be changed.
lc_messages = 'en_US.UTF-8'         # locale for system error message
                    # strings
lc_monetary = 'en_US.UTF-8'         # locale for monetary formatting
lc_numeric = 'en_US.UTF-8'          # locale for number formatting
lc_time = 'en_US.UTF-8'             # locale for time formatting

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

# - 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?


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

custom_variable_classes = ''        # list of custom variable class names

这里是 pg_hba.conf 文件：

local   all             postgres                                trust

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
host    all             postgres             192.168.1.0/24         trust
host    all             all                  127.0.0.0/24          trust

我尝试启用/禁用 autovacuum、禁用日志记录等。没有成功。 M 系统有 8 个 CPU 和 3GB 内存，我有 1 TB 的专用空间用于这个 SQL 服务器。

感谢任何想法和帮助。

注意：This page 不能解决我的问题。

结论：获得 PGPool-II 3.x。非常容易设置（如答案中所述）并且非常快！

Answer 1

有趣的是，MySQL 建立连接的速度更快。在 PHP 这样的环境中，连接的建立和拆除速度非常快，而不是在 Rails 或 JVM 等应用程序环境中运行时间更长的连接。

在这种情况下，为 Postgres 使用连接池可能是有意义的。想到两个：

PGPool-II：http://www.pgpool.net/mediawiki/index.php/Main_Page

PgBouncer：http://pgfoundry.org/projects/pgbouncer/

我使用过 PGPool-II，它的设置非常简单。

Answer 2

嗯....我不是这里的专家，但是您不想将您的 hba 绑定到 NIC 或 localhost 而不是网络吗？

在 Windows 机器上，

# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

你有多少内存？多少虚拟内存？如果 VM 变得太大，它会减慢机器的速度。但有时你只是需要它。

Answer 3

我对 PostgreSQL 了解不多，但我可以告诉你为什么 MySQL 对这个特定的查询速度很快。

在 InnoDB 中，主键索引是聚集索引，这意味着页面以与主键相同的物理顺序存储。

最后，当你请求ORDER BY DESC时，MySQL只是反向读取索引，所以性能和ASC一样。