PostgreSQL启动： 一：postgres启动
[postgres@cjc-db-01 ~]$postgres -D /pg/data &
相关参数，见帮助信息
[postgres@cjc-db-01 ~]$ postgres --help
二：pg_ctl启动 指定数据路径和数据文件
pg_ctl -D /pg/data -l /pg/log/pg.log start
查看pg_ctl命令帮助信息 pg_ctl工具主要用于PostgreSQL server 初始化、启动、停止、重启等操作。
[postgres@cjc-db-01 ~]$ pg_ctl --help pg_ctl is a utility to initialize, start, stop, or control a PostgreSQL server. Usage: pg_ctl init[db] [-D DATADIR] [-s] [-o OPTIONS] pg_ctl start [-D DATADIR] [-l FILENAME] [-W] [-t SECS] [-s] [-o OPTIONS] [-p PATH] [-c] pg_ctl stop [-D DATADIR] [-m SHUTDOWN-MODE] [-W] [-t SECS] [-s] pg_ctl restart [-D DATADIR] [-m SHUTDOWN-MODE] [-W] [-t SECS] [-s] [-o OPTIONS] [-c] pg_ctl reload [-D DATADIR] [-s] pg_ctl status [-D DATADIR] pg_ctl promote [-D DATADIR] [-W] [-t SECS] [-s] pg_ctl kill SIGNALNAME PID Common options: -D, --pgdata=DATADIR location of the database storage area -s, --silent only print errors, no informational messages -t, --timeout=SECS seconds to wait when using -w option -V, --version output version information, then exit -w, --wait wait until operation completes (default) -W, --no-wait do not wait until operation completes -?, --help show this help, then exit If the -D option is omitted, the environment variable PGDATA is used. Options for start or restart: -c, --core-files allow postgres to produce core files -l, --log=FILENAME write (or append) server log to FILENAME -o, --options=OPTIONS command line options to pass to postgres (PostgreSQL server executable) or initdb -p PATH-TO-POSTGRES normally not necessary Options for stop or restart: -m, --mode=MODE MODE can be "smart", "fast", or "immediate" Shutdown modes are: smart quit after all clients have disconnected fast quit directly, with proper shutdown (default) immediate quit without complete shutdown; will lead to recovery on restart Allowed signal names for kill: ABRT HUP INT QUIT TERM USR1 USR2 Report bugs to <pgsql-bugs@postgresql.org>.
PostgreSQL关闭： 一：直接向运行的postgres主进程发送signal信号，停止数据库 二：使用pg_ctl命令停止数据库 1.smart 智能关机模式
quit after all clients have disconnected
在接收到关库请求后，不在允许新的连接，等已有连接全部结束后才关闭数据库，速度慢。 命令：
pg_ctl -D /pg/data -l /pg/log/pg.log stop -m smart
对应日志：
2023-01-18 14:37:17.820 CST [2711] LOG: received smart shutdown request 2023-01-18 14:37:31.907 CST [2711] LOG: worker process: logical replication launcher (PID 2718) exited with exit code 1 2023-01-18 14:37:31.914 CST [2713] LOG: shutting down 2023-01-18 14:37:31.990 CST [2711] LOG: database system is shut down
2.fast 快速关闭模式
quit directly, with proper shutdown (default)
不在允许新的连接，向所有活跃服务进程发送SIGTERM信号，让它们立即退出，然后等待所有子进程退出并关闭数据库。 命令：
pg_ctl -D /pg/data -l /pg/log/pg.log stop -m fast
不指定-m参数，默认就是fast
pg_ctl -D /pg/data -l /pg/log/pg.log stop
对应日志：
2023-01-18 14:38:33.444 CST [24347] LOG: received fast shutdown request 2023-01-18 14:38:33.454 CST [24347] LOG: aborting any active transactions 2023-01-18 14:38:33.469 CST [24347] LOG: worker process: logical replication launcher (PID 24354) exited with exit code 1 2023-01-18 14:38:33.472 CST [24349] LOG: shutting down 2023-01-18 14:38:33.525 CST [24347] LOG: database system is shut down
3.immediate 立即关闭模式
quit without complete shutdown; will lead to recovery on restart
主进程postgres向所有子进程发送SIGQUIT信号，并立即退出，所有子进程也会立即退出，下次启动时数据库会重放WAL日志进行恢复。 命令：
pg_ctl -D /pg/data -l /pg/log/pg.log stop -m immediate
对应日志：
2023-01-18 14:40:24.574 CST [24491] LOG: received immediate shutdown request 2023-01-18 14:40:24.600 CST [24496] WARNING: terminating connection because of crash of another server process 2023-01-18 14:40:24.600 CST [24496] DETAIL: The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory. 2023-01-18 14:40:24.600 CST [24496] HINT: In a moment you should be able to reconnect to the database and repeat your command. 2023-01-18 14:40:24.607 CST [24491] LOG: database system is shut down
查看启动日志，执行了自动恢复
2023-01-18 14:41:03.117 CST [24553] LOG: database system was interrupted; last known up at 2023-01-18 14:40:10 CST 2023-01-18 14:41:03.978 CST [24553] LOG: database system was not properly shut down; automatic recovery in progress 2023-01-18 14:41:03.982 CST [24553] LOG: invalid record length at 0/171C9B0: wanted 24, got 0 2023-01-18 14:41:03.982 CST [24553] LOG: redo is not required 2023-01-18 14:41:04.009 CST [24552] LOG: database system is ready to accept connections
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