checkpoint参数描述：
checkpoint的时候会将所有的脏数据都flush到磁盘上
checkpoint_timeout：
两次checkpoint间隔时长
checkpoint_segments:
walwriter进程参数描述：
fsync：
该参数直接控制wal日志是否先写入磁盘，然后在更新数据。批量更新/插入时刻off此项，加快执行速度。（off不影响wal writer process 进程运行）
synchronous_commit：
flushwal日志到xlog后才给xact（事务）返回信息。此参数也控制流复制是同步还是异步。
wal_sync_method：
wal日志写到磁盘的控制方式。
full_page_writes：
是否将wal日志一个page整个写入磁盘。好处不会有数据一半写入另一半崩溃时未来得及未写入,不好恢复。
wal_buffers：
wal日志缓冲区大小最小是32K（4个page）。
wal_writer_delay：
两次wal日志缓冲区flush到磁盘间隔时长。
commit_delay：
已经提交的数据在wal缓冲区存放的时长。（为了等够了一定数额一并提交）
commit_siblings：
超过这个数值就将wal缓冲区应该提交的一并flush到磁盘。（参见
commit_delay
）
归档：
archive_mode:
归档命令。
archive_command：
将xlog拷贝到一个地方的命令。
#------------------------------------------------------------------------------ # 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) ...skipping... #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 #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 = 16 # 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 = on # allows archiving to be done # (change requires restart) archive_command = 'cp %p /home/pg93/test_rep/arch/%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 = 0 # force a logfile segment switch after this # number of seconds; 0 disables
流复制：
max_wal_senders:
允许多少个流复制协议连接过来。一个流复制协议会产生一个walsender进程（一个master可能会有多个standby节点进行流复制）。
wal_keep_segments：
synchronous_standby_names：
同步流复制允许standby节点的名字。（'*' = all）
hot_standby：
standby节点是否允许执行SQL查询。
max_standby_archive_delay&max_standby_streaming_delay：
wal_receiver_status_interval：
反馈给主节点自己已经接受（
replies
）到数据信息。
hot_standby_Feedback：
如果standby和master发生了冲突是否将此冲突信息反馈给master。
#------------------------------------------------------------------------------ # REPLICATION #------------------------------------------------------------------------------ # - Sending Server(s) - # Set these on the master and on any standby that will send replication data. max_wal_senders = 13 # max number of walsender processes # (change requires restart) wal_keep_segments = 16 # in logfile segments,16MB each; 0 disables #wal_sender_timeout = 60s # in milliseconds; 0 disables # - Master Server - # These settings are ignored on a standby server. #synchronous_standby_names = '' # standby servers that provide sync rep # comma-separated list of application_name # from standby(s); '*' = all #vacuum_defer_cleanup_age = 0 # 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 # (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 #wal_receiver_timeout = 60s # time that receiver waits for # communication from master # in milliseconds; 0 disables
log_autovacuum_min_duration:
在规定时长内未完成的vacuum予以记录日志
autovacuum_max_workers：
允许同事开启的vacuum进程数
autovacuum_naptime：
两次vacuum间隔时间
autovacuum_vacuum_threshold：
达到某表DML操作的最小行数则vacuum
autovacuum_analyze_threshold:
激活自动analyze操作的最小行数，analyze有利于对sql语句进行更精准的plan(这是由于explain用到的pg_class列reltuples and relpages are not updated on-the-fly)
autovacuum_vacuum_scale_factor：
表示autovacuum的vacuum操作所需的变更量阈值,当这个表的update/delete的tuple总数大于(pg_class.reltuples*autovacuum_vacuum_scale_factor+autovacuum_vacuum_threshold)时,触发vacuum操作.
http://www.postgresql.org/docs/9.2/static/routine-vacuuming.html#AUTOVACUUM
autovacuum_analyze_scale_factor：
表示autovacuum的analyze操作所需的变更量阈值,当这个表的INSERT/update/delete的tuple总数大于(pg_class.reltuples*autovacuum_analyze_scale_factor+autovacuum_analyze_threshold)时,触发analyze操作
autovacuum_freeze_max_age：
某表的pg_class.relfrozenxid的最大值，如果超出此值则重置xid
autovacuum_vacuum_cost_delay：
运行一次vacuum的时长，如果超过此值则休眠然后起来接着vacuum(vacuum很好I/O)
#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_multixact_freeze_max_age = 400000000 # maximum Multixact 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