PostgreSQL的pg_ctl命令
pg_ctl 是 PostgreSQL 用于控制数据库服务器进程的命令行工具。它提供了启动、停止、重启数据库服务器以及管理其运行状态的手段。pg_ctl 命令尤其适用于从命令行或脚本中管理 PostgreSQL 服务，而不是通过操作系统的服务控制管理器。
基础信息
OS版本：Red Hat Enterprise Linux Server release 7.9 (Maipo)
DB版本：16.2
pg软件目录：/home/pg16/soft
pg数据目录：/home/pg16/data
端口：5777
常用的 pg_ctl 命令
-
启动数据库服务器
pg_ctl start -D /home/pg16/data
[pg16@test ~]$ pg_ctl start -D /home/pg16/data
waiting for server to start....2024-04-09 23:16:14.784 PDT [19476] LOG: starting PostgreSQL 16.2 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44), 64-bit
2024-04-09 23:16:14.784 PDT [19476] LOG: listening on IPv4 address "0.0.0.0", port 5777
2024-04-09 23:16:14.785 PDT [19476] LOG: listening on IPv6 address "::", port 5777
2024-04-09 23:16:14.786 PDT [19476] LOG: listening on Unix socket "/tmp/.s.PGSQL.5777"
2024-04-09 23:16:14.790 PDT [19479] LOG: database system was shut down at 2024-04-09 23:16:12 PDT
2024-04-09 23:16:14.794 PDT [19476] LOG: database system is ready to accept connectionsdone
server started
`-D` 参数指定数据库数据目录的位置，是必需的。可以添加 `-l logfile` 参数来指定日志文件的位置。
-
停止数据库服务器
pg_ctl stop -D /home/pg16/data
[pg16@test ~]$ pg_ctl stop -D /home/pg16/data
waiting for server to shut down....2024-04-09 23:16:50.021 PDT [19476] LOG: received fast shutdown request
2024-04-09 23:16:50.022 PDT [19476] LOG: aborting any active transactions
2024-04-09 23:16:50.023 PDT [19476] LOG: background worker "logical replication launcher" (PID 19482) exited with exit code 1
2024-04-09 23:16:50.024 PDT [19477] LOG: shutting down
2024-04-09 23:16:50.025 PDT [19477] LOG: checkpoint starting: shutdown immediate
2024-04-09 23:16:50.028 PDT [19477] LOG: checkpoint complete: wrote 3 buffers (0.0%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.001 s, sync=0.001 s, total=0.005 s; sync files=2, longest=0.001 s, average=0.001 s; distance=0 kB, estimate=0 kB; lsn=0/17B9918, redo lsn=0/17B9918
2024-04-09 23:16:50.032 PDT [19476] LOG: database system is shut downdone
server stopped
停止数据库时，你可以通过添加 `-m` 参数来指定停机模式：`smart`（优雅地等待数据库关闭），`fast`（立即断开客户端连接并关闭数据库），`immediate`（不等待，直接关闭数据库，可能需要恢复操作）。
-
重启数据库服务器
pg_ctl restart -D /home/pg16/data
[pg16@test ~]$ pg_ctl restart -D /home/pg16/data
waiting for server to shut down....2024-04-09 23:17:27.711 PDT [19552] LOG: received fast shutdown request
2024-04-09 23:17:27.712 PDT [19552] LOG: aborting any active transactions
2024-04-09 23:17:27.713 PDT [19552] LOG: background worker "logical replication launcher" (PID 19558) exited with exit code 1
2024-04-09 23:17:27.713 PDT [19553] LOG: shutting down
2024-04-09 23:17:27.713 PDT [19553] LOG: checkpoint starting: shutdown immediate
2024-04-09 23:17:27.722 PDT [19553] LOG: checkpoint complete: wrote 3 buffers (0.0%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.001 s, sync=0.001 s, total=0.010 s; sync files=2, longest=0.001 s, average=0.001 s; distance=0 kB, estimate=0 kB; lsn=0/17B9990, redo lsn=0/17B9990
2024-04-09 23:17:27.725 PDT [19552] LOG: database system is shut downdone
server stopped
waiting for server to start....2024-04-09 23:17:27.825 PDT [19561] LOG: starting PostgreSQL 16.2 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44), 64-bit
2024-04-09 23:17:27.825 PDT [19561] LOG: listening on IPv4 address "0.0.0.0", port 5777
2024-04-09 23:17:27.825 PDT [19561] LOG: listening on IPv6 address "::", port 5777
2024-04-09 23:17:27.827 PDT [19561] LOG: listening on Unix socket "/tmp/.s.PGSQL.5777"
2024-04-09 23:17:27.830 PDT [19564] LOG: database system was shut down at 2024-04-09 23:17:27 PDT
2024-04-09 23:17:27.833 PDT [19561] LOG: database system is ready to accept connectionsdone
server started
`restart` 命令会停止然后重新启动数据库服务器。也可以使用 `-m` 参数指定停机模式。
-
查询数据库服务器状态
pg_ctl status -D /home/pg16/data
[pg16@test ~]$ pg_ctl status -D /home/pg16/data
pg_ctl: server is running (PID: 19561)
/home/pg16/soft/bin/postgres "-D" "/home/pg16/data"
这会显示数据库服务器是否正在运行以及其 PID。
其他参数可以通过help查看
[pg16@test ~]$ 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 logrotate [-D DATADIR] [-s]pg_ctl kill SIGNALNAME PIDCommon 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 necessaryOptions for stop or restart:-m, --mode=MODE MODE can be "smart", "fast", or "immediate"Shutdown modes are:smart quit after all clients have disconnectedfast quit directly, with proper shutdown (default)immediate quit without complete shutdown; will lead to recovery on restartAllowed signal names for kill:ABRT HUP INT KILL QUIT TERM USR1 USR2Report bugs to <pgsql-bugs@lists.postgresql.org>.
PostgreSQL home page: <https://www.postgresql.org/>
注意事项
- 使用
pg_ctl命令时，确保你有足够的权限。在许多系统中，可能需要以 PostgreSQL 用户（通常名为postgres）的身份运行这些命令。 - 请小心使用停机模式，特别是
immediate模式，因为它可能导致数据未被完全写入磁盘而损坏。 - 如果使用的是某些 Linux 发行版本或 Windows，PostgreSQL 服务可能通过操作系统的服务控制管理器来管理。在这种情况下，也可以使用系统命令（如
systemctl或service命令，Windows 服务管理器）来管理 PostgreSQL 服务。
总结
pg_ctl 是 PostgreSQL 管理中非常强大的工具，只需通过简单的命令行操作就可以有效地控制数据库服务器。
谨记：心存敬畏，行有所止。
