pg无法启动

现象：

[root@pg ~]# systemctl status postgresql
● postgresql.service - PostgreSQL 9.6.24 database server
   Loaded: loaded (/usr/lib/systemd/system/postgresql.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Wed 2023-11-08 11:15:14 CST; 13s ago
  Process: 26250 ExecStop=/usr/local/pgsql/bin/pg_ctl stop -m fast -w -D /usr/local/pgsql/pgdata (code=exited, status=0/SUCCESS)
  Process: 26267 ExecStart=/usr/local/pgsql/bin/pg_ctl start -w -D /usr/local/pgsql/pgdata -l /usr/local/pgsql/pgdata/pg_log/startup.log (code=exited, status=1/FAILURE)
 Main PID: 23576 (code=exited, status=0/SUCCESS)

Nov 08 11:15:13 pg systemd[1]: Starting PostgreSQL 9.6.24 database server...
Nov 08 11:15:14 pg systemd[1]: postgresql.service: control process exited, code=exited status=1
Nov 08 11:15:14 pg systemd[1]: Failed to start PostgreSQL 9.6.24 database server.
Nov 08 11:15:14 pg systemd[1]: Unit postgresql.service entered failed state.
Nov 08 11:15:14 pg systemd[1]: postgresql.service failed.

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从上面的报错中，可以看到：
1、关闭正常，启动失败
2、启动日志存放在/usr/local/pgsql/pgdata/pg_log/startup.log文件中

检查启动日志

LOG:  redirecting log output to logging collector process
HINT:  Future log output will appear in directory "pg_log".
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日志重定向到了配置的日志路径中，检查pg的参数文件，确定日志的文件名
[postgres@pg pgdata]$ cat postgresql.conf

#self define
listen_addresses = '*'
port = 5432
logging_collector = on
log_directory = 'pg_log'
log_filename = 'postgresql-%a.log'
log_truncate_on_rotation = on
log_rotation_age = 1d #这个mon文件保留多久才被允许覆盖，第2天产生的Tue了
log_rotation_size = 0

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从这里看到，日志目录是pg_log，日志文件名是postgresql-%a.log，这里的%a是星期几的缩写，今天星期三，那么日志文件名就是postgresql-Wed.log

查看真正的数据库启动日志postgresql-Wed.log

LOG:  configuration file "/usr/local/pgsql/pgdata/pg_hba.conf" contains no entries
FATAL:  could not load pg_hba.conf
LOG:  database system is shut down
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从这里可以看到，无法加载pg_hba.conf文件，原因是这个文件中的内容全部被注释，没有可运行的内容。这里面，至少存在一条

local   all             all                                     trust
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再次启动，正常

LOG:  MultiXact member wraparound protections are now enabled
LOG:  database system is ready to accept connections
LOG:  autovacuum launcher started
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