PostgreSQL的HA解决方案-1主从和备份（master/slave and backup）

一.部署说明

1.1 实施环境

本文档实验环境如下：

PGSQL主机: 192.168.1.45

PGSQL备机: 192.168.1.50

软件和系统版本

Pgsql 版本: pgsql 9.2.4

Linux 版本: Redhat 5.8

1.2 文档说明

　　本文档详细说明了PG的双机扩展，使pgsql数据库具备双机热备流复制功能。注意，双机热备中存在主从关系，这样才能保证数据的一直性，主机操作都可以，但从机只能用作查询。所以热备的意义在于分担主机的查询压力，备份主机数据，当主机出问题后，从机稍加修改就可以变为主机。

　　为了试验减少不必要的麻烦，本系列试验中，各个主机之间的通信，都是设置为无密码访问，但对于实际生产，需要根据实际需要，配置密码，增强集群的安全性。

二.配置步骤

　　1.1 （主从一样）。编辑data/pg_hba.conf 访问控制文件。　　　　

　　　　在配置pgsql之前，首先要设置两台服务器使得postgres用户可以无密码相互访问。 配置过程一定要分清主从机。因为实验的两台虚拟机所在网段都是192.168.1.0/24.所以，新增如下：

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/            trust
host    all             all             192.168.1.0/          trust
# IPv6 local connections:
host    all             all             ::/                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     postgres                                trust
#host    replication     postgres        127.0.0.1/            trust
host    replication     postgres        192.168.1.0/           trust
#host    replication     postgres        ::/                 trust

　　1.2 （主从一样）。编辑data/postgresql.conf 数据库配置文件。

　　　　主从机的数据库postgresql.conf配置相同，主要是方便接下来的将主机的data文件直接备份还原到从机，并且也方便将来主从切换。请对照默认参数设置，设置相应参数，一些参数的设置，如

max_connections = 100 　　　　　　#最大连接数的设置，当超过最大链接时，数据库拒绝访问。

shared_buffers = 1280MB　　　　　　#共享内存，主要是和服务器的硬件和实际的项目需求相关，理论上在硬件资源允许的情况下，此值越大越好。

wal_level = hot_standby　　　　　　　#开启主从热备模式

fsync = on　　　　　　　　　　　　　　#异步数据同步

full_page_writes = on

checkpoint_segments = 32　　　　　　#关于脏数据写回的
archive_mode = on               　　　　　#打开归档模式

archive_command ='cp %p /opt/bjca3/pgsql/data/archive/%f ' #将归档文件保存在data/archive目录下
max_wal_senders = 2　　　　　　　　　#根据从机的个数设置，实验中只有一个从机，所以只设置为1

wal_keep_segments = 250　　　　　　　

hot_standby = on   　　　　　　　　　　#在配置中，并不是每个配置都起作用的，数据库会根据当前的主从机的属性，自动判断哪些是主机的配置，哪些是从机的配置，配置文档中也有说明。
max_standby_archive_delay = 300s

max_standby_streaming_delay = 300s

wal_receiver_status_interval = 10s

hot_standby_feedback = on

log_line_prefix = '[%t] '

　　　　详细的配置及含义请看下边的配置文件。

# -----------------------------
# 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 = 'localhost'        # what IP address(es) to listen on;
listen_addresses = '*'            # what IP address(es) to listen on;
                    # comma-separated list of addresses;
                    # defaults to 'localhost'; use '*' for all
                    # (change requires restart)
#port =                 # (change requires restart)
port =                 # (change requires restart)
max_connections =             # (change requires restart)
# Note:  Increasing max_connections costs ~ bytes of shared memory per
# connection slot, plus lock space (see max_locks_per_transaction).
#superuser_reserved_connections =     # (change requires restart)
#unix_socket_directory = ''        # (change requires restart)
#unix_socket_group = ''            # (change requires restart)
#unix_socket_permissions =         # begin with  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 = 'ALL:!ADH:!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 =         # TCP_KEEPIDLE, in seconds;
                    #  selects the system default
#tcp_keepalives_interval =         # TCP_KEEPINTVL, in seconds;
                    #  selects the system default
#tcp_keepalives_count =         # TCP_KEEPCNT;
                    #  selects the system default

#------------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#------------------------------------------------------------------------------

# - Memory -

#shared_buffers = 32MB            # min 128kB
shared_buffers = 256MB            # min 128kB
                    # (change requires restart)
#temp_buffers = 8MB            # min 800kB
#max_prepared_transactions =         # zero disables the feature
                    # (change requires restart)
# Note:  Increasing max_prepared_transactions costs ~ 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 = -            # limits per-session temp file space
                    # in kB, or - for no limit

# - Kernel Resource Usage -

#max_files_per_process =         # min
                    # (change requires restart)
#shared_preload_libraries = ''        # (change requires restart)

# - Cost-Based Vacuum Delay -

#vacuum_cost_delay = 0ms        # - milliseconds
#vacuum_cost_page_hit =         # - credits
#vacuum_cost_page_miss =         # - credits
#vacuum_cost_page_dirty =         # - credits
#vacuum_cost_limit =         # - credits

# - Background Writer -

#bgwriter_delay = 200ms            # -10000ms between rounds
#bgwriter_lru_maxpages =         # - max buffers written/round
#bgwriter_lru_multiplier = 2.0        # -10.0 multipler on buffers scanned/round

# - Asynchronous Behavior -

#effective_io_concurrency =         # -;  disables prefetching

#------------------------------------------------------------------------------
# WRITE AHEAD LOG
#------------------------------------------------------------------------------

# - Settings -

#wal_level = minimal            # minimal, archive, or hot_standby
wal_level = hot_standby            # minimal, archive, or hot_standby
                    # (change requires restart)
#fsync = on                # turns forced synchronization on or off
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
full_page_writes = on            # recover from partial page writes
#wal_buffers = -            # min 32kB, - sets based on shared_buffers
                    # (change requires restart)
#wal_writer_delay = 200ms        # - milliseconds

#commit_delay =             # range -, in microseconds
#commit_siblings =             # range -

# - Checkpoints -

#checkpoint_segments =         # in logfile segments, min , 16MB each
#checkpoint_timeout = 5min        # range 30s-1h
#checkpoint_completion_target = 0.5    # checkpoint target duration, 0.0 - 1.0
#checkpoint_warning = 30s        #  disables

# - Archiving -

#archive_mode = off        # allows archiving to be done
archive_mode = on        # allows archiving to be done
                # (change requires restart)
#archive_command = ''        # command to use to archive a logfile segment
archive_command = 'cp %p /usr/local/pgsql/data/archive/%f'        # 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 =         # force a logfile segment switch after this
                # number of seconds;  disables

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

# - Sending Server(s) -

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

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

# - Master Server -

# These settings are ignored on a standby server.

#synchronous_standby_names = ''    # standby servers that provide sync rep
synchronous_standby_names = '*'    # standby servers that provide sync rep
                # comma-separated list of application_name
                # from standby(s); '*' = all
#vacuum_defer_cleanup_age =     # 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
hot_standby = on            # "on" allows queries during recovery
                    # (change requires restart)
#max_standby_archive_delay = 30s    # max delay before canceling queries
max_standby_archive_delay = 300s    # max delay before canceling queries
                    # when reading WAL from archive;
                    # - allows indefinite delay
#max_standby_streaming_delay = 30s    # max delay before canceling queries
max_standby_streaming_delay = 300s    # max delay before canceling queries
                    # when reading streaming WAL;
                    # - allows indefinite delay
#wal_receiver_status_interval = 10s    # send replies at least this often
wal_receiver_status_interval = 10s    # send replies at least this often
                    #  disables
#hot_standby_feedback = off        # send info from standby to prevent
hot_standby_feedback = on        # 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_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 = 128MB

# - Genetic Query Optimizer -

#geqo = on
#geqo_threshold =
#geqo_effort =             # range -
#geqo_pool_size =             # selects default based on effort
#geqo_generations =             # 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 =     # range -
#constraint_exclusion = partition    # on, off, or partition
#cursor_tuple_fraction = 0.1        # range 0.0-1.0
#from_collapse_limit =
#join_collapse_limit =         #  disables collapsing of explicit
                    # JOIN clauses

#------------------------------------------------------------------------------
# ERROR REPORTING AND LOGGING
#------------------------------------------------------------------------------

# - Where to Log -

#log_destination = 'stderr'        # Valid values are combinations of
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 = off        # Enable capturing of stderr and csvlog
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,
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,
log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'    # log file name pattern,
                    # can include strftime() escapes
#log_file_mode =             # creation mode for log files,
                    # begin with  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.   disables.
#log_rotation_size = 10MB        # Automatic rotation of logfiles will
                    # happen after that much log output.
                    #  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 = -    # - is disabled,  logs all statements
                    # and their durations, >  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 ( 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 = -            # log temporary files equal or larger
                    # than the specified size in kilobytes;
                    # - disables,  logs all temp files
log_timezone = 'PRC'

#------------------------------------------------------------------------------
# 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 =      # (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 = -    # - disables,  logs all actions and
                    # their durations, >  logs only
                    # actions running at least this number
                    # of milliseconds.
#autovacuum_max_workers =         # max number of autovacuum subprocesses
                    # (change requires restart)
#autovacuum_naptime = 1min        # time between autovacuum runs
#autovacuum_vacuum_threshold =     # min number of row updates before
                    # vacuum
#autovacuum_analyze_threshold =     # 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 =     # maximum XID age before forced vacuum
                    # (change requires restart)
#autovacuum_vacuum_cost_delay = 20ms    # default vacuum cost delay for
                    # autovacuum, in milliseconds;
                    # - means use vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -    # default vacuum cost limit for
                    # autovacuum, - 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 =             # in milliseconds,  is disabled
#vacuum_freeze_min_age =
#vacuum_freeze_table_age =
#bytea_output = 'hex'            # hex, escape
#xmlbinary = 'base64'
#xmloption = 'content'

# - Locale and Formatting -

datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
timezone = 'PRC'
#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 =             # min -, max
#client_encoding = sql_ascii        # actually, defaults to database
                    # encoding

# These settings are initialized by initdb, but they can 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

# 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 =         # min
                    # (change requires restart)
# Note:  Each lock table slot uses ~ bytes of shared memory, and there are
# max_locks_per_transaction * (max_connections + max_prepared_transactions)
# lock table slots.
#max_pred_locks_per_transaction =     # min
                    # (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
#------------------------------------------------------------------------------

# Add settings for extensions here

　　1.3 此时主从数据库的配置是相同的，所以可以将主库直接备份，然后还原至从库。其实对于从库，配置本身很简单，只是因为考虑到接下来的主从切换麻烦，所以讲主从配置成一样的。

此时可以使用PG自带的pg_basebackup工具，对主机进行远程基础备份。

　　在从机中执行：pg_basebackup -F p -D $PGDATA -x -v -h db1 -w

　　将主机的数据库远程备份并恢复到从机中。其中db1是我添加在系统hosts里的，对于不想添加的，可以直接使用Ip地址。其实hosts中的文件就是给出不同IP的别名，方便使用。其他参数请--help.

　　1.4 备份还原到从机后，需要添加另外一个配置文件：recovery.conf,此时才把主机与从机区分开来。在PGHOME目录下的share文件夹中有实例文件，将之拷贝过来，修改即可。

　　　　执行cp /usr/local/pgsql/share/recovery.conf.sample /usr/local/pgsql/data/recovery.conf.　

　　　　主要配置：

standby_mode = 'on'　　　　　　　　　　#开启从机模式

trigger_file = '/usr/local/pgsql/data/pg.trigger'#注意路径是可以自定义的，但是当主机失效，从机变为主机是，为产生该文件，但当重新恢复为从机自己写的shell脚本要删除该文件，注意权限问题。

primary_conninfo = 'host=db1'

　　1.5 此时可以启动从机的数据库了。此时会报如下错误：

FATAL:  data directory "/usr/local/pgsql/data" has group or world access
DETAIL:  Permissions should be u=rwx (0700).

　　所以，此时要修改data的权限为700.修改之后启动，就没问题了。此时查看启动日志：data/pg_log中的日志如下：

LOG:  creating missing WAL directory "pg_xlog/archive_status"
LOG:  entering standby mode
LOG:  redo starts at /
LOG:  consistent recovery state reached at /40000C8
LOG:  database system is ready to accept read only connections
LOG:  streaming replication successfully connected to primary

　　说明，此时从机已经开启了从机模式，只读模式等待连接，并且已经连接到主机的数据库。

　　1.6验证数据同步。

　　　　①在主库中创建表，查看从库中是否有同样的数据表即可。

　　　　②当然也可以主机中在psql中执行：select * from pg_stat_replication;

pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | state | sent_location | write_locat
ion | flush_location | replay_location | sync_priority | sync_state
-------+----------+----------+------------------+--------------+-----------------+-------------+-------------------------------+-----------+---------------+------------
----+----------------+-----------------+---------------+------------
22877 | 10 | postgres | walreceiver | 192.168.1.50 | | 47967 | 2015-09-18 16:09:13.711784+08 | streaming | 0/5016334 | 0/5016334
| 0/5016334 | 0/5016334 | 1 | sync

　　　　③在主机中运行命令：top -c -u postgres

12707 postgres 15 0 4612 1368 1108 S 0.0 0.1 0:00.09 bash
13190 postgres 18 0 4992 1256 1072 T 0.0 0.1 0:00.02 vi pg_hba.conf
17668 postgres 15 0 281m 16m 15m S 0.0 1.6 0:00.03 /usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
17669 postgres 18 0 9124 660 356 S 0.0 0.1 0:00.00 postgres: logger process
17671 postgres 16 0 281m 3164 2808 S 0.0 0.3 0:00.34 postgres: checkpointer process
17672 postgres 15 0 281m 2544 2208 S 0.0 0.2 0:00.01 postgres: writer process
17673 postgres 15 0 281m 840 504 S 0.0 0.1 0:00.00 postgres: wal writer process
17674 postgres 18 0 282m 1680 984 S 0.0 0.2 0:00.00 postgres: autovacuum launcher process
17675 postgres 18 0 9168 688 356 S 0.0 0.1 0:00.00 postgres: archiver process last was 000000010000000000000004
17676 postgres 16 0 9168 796 424 S 0.0 0.1 0:00.03 postgres: stats collector process
22877 postgres 18 0 282m 2176 1360 S 0.0 0.2 0:00.00 postgres: wal sender process postgres 192.168.1.50(47967) streaming 0/5016334
25439 postgres 15 0 2432 1068 816 R 0.0 0.1 0:00.19 top -c -u postgres

　　　　④在从机中运行命令：top -c -u postgres

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12446 postgres 15 0 4612 1384 1120 S 0.0 0.1 0:00.08 bash
19711 postgres 15 0 4612 1376 1116 S 0.0 0.1 0:00.02 bash
20040 postgres 15 0 4612 1360 1124 S 0.0 0.1 0:00.01 bash
20152 postgres 15 0 4612 1388 1124 S 0.0 0.1 0:00.05 bash
21809 postgres 18 0 281m 16m 15m S 0.0 1.6 0:00.05 /usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
21810 postgres 22 0 9120 652 352 S 0.0 0.1 0:00.00 postgres: logger process
21811 postgres 15 0 282m 1784 1420 S 0.0 0.2 0:00.00 postgres: startup process recovering 000000010000000000
21812 postgres 16 0 281m 2988 2640 S 0.0 0.3 0:00.00 postgres: checkpointer process
21813 postgres 15 0 281m 2532 2200 S 0.0 0.2 0:00.00 postgres: writer process
21814 postgres 16 0 9164 780 408 S 0.0 0.1 0:00.00 postgres: stats collector process
21815 postgres 15 0 282m 1768 1244 S 0.0 0.2 0:00.28 postgres: wal receiver process streaming 0/50163B8
24569 postgres 15 0 2432 1072 816 R 0.0 0.1 0:00.14 top -c -u postgres

　　都可以证明已经正常启动。