有个开发环境，因为磁盘空间满了，有人直接将pg_wal下的文件rm了，然后，重启报错
2020-06-28 18:13:59.148 CST [10387]: LOG: database system was shut down at 2020-06-28 18:12:41 CST 2020-06-28 18:13:59.148 CST [10387]: LOG: invalid primary checkpoint record 2020-06-28 18:13:59.148 CST [10387]: PANIC: could not locate a valid checkpoint record 2020-06-28 18:13:59.560 CST [10342]: LOG: startup process (PID 10387) was terminated by signal 6: Aborted 2020-06-28 18:13:59.560 CST [10342]: LOG: aborting startup due to startup process failure 2020-06-28 18:13:59.581 CST [10342]: LOG: database system is shut down
从日志文件也可以看到因为wal segment找不到，而无法启动：
$ more postgresql-Sun.log 2020-06-28 18:17:25.882 CST [12259]: LOG: database system was shut down at 2020-06-28 18:16:48 CST 2020-06-28 18:17:25.882 CST [12259]: LOG: recovered replication state of node 1 to 2/F6A001C0 2020-06-28 18:17:25.887 CST [12216]: LOG: database system is ready to accept connections 2020-06-28 18:17:25.912 CST [12269]: LOG: logical replication apply worker for subscription "b_sub" has started 2020-06-28 18:17:25.922 CST ap a [12272]: LOG: starting logical decoding for slot "publication_abce" 2020-06-28 18:17:25.922 CST ap a [12272]: DETAIL: Streaming transactions committing after F/CD215498, reading WAL from F/CD215498. 2020-06-28 18:17:25.922 CST ap a [12272]: ERROR: requested WAL segment 000000010000000F000000CD has already been removed 2020-06-28 18:17:25.922 CST [12269]: ERROR: could not receive data from WAL stream: ERROR: requested WAL segment 000000010000000F000000CD has already been removed 2020-06-28 18:17:25.923 CST [12216]: LOG: background worker "logical replication worker" (PID 12269) exited with exit code 1 2020-06-28 18:17:30.935 CST [12324]: LOG: logical replication apply worker for subscription "b_sub" has started 2020-06-28 18:17:30.941 CST ap a [12325]: LOG: starting logical decoding for slot "publication_abce" 2020-06-28 18:17:30.941 CST ap a [12325]: DETAIL: Streaming transactions committing after F/CD215498, reading WAL from F/CD215498. 2020-06-28 18:17:30.941 CST ap a [12325]: ERROR: requested WAL segment 000000010000000F000000CD has already been removed 2020-06-28 18:17:30.941 CST [12324]: ERROR: could not receive data from WAL stream: ERROR: requested WAL segment 000000010000000F000000CD has already been removed 2020-06-28 18:17:30.943 CST [12216]: LOG: background worker "logical replication worker" (PID 12324) exited with exit code 1
因为不是重要环境，直接使用pg_resetwal直接重置了wal和其他控制信息，然后重启。
$ pg_resetwal -f /data/pgdata/11/data Write-ahead log reset
pg_resetwal会清空存储在pg_control文件中的wal和其他可选的控制信息。不到万不得已，可别使用这个命令。
执行该工具之后，数据库可以启动，但是可能会包含不一致的数据，因为会有事务部分提交。重启后，建议立即将数据dump出来，运行initdb并reload数据。检查数据一致性并根据需要进行数据修复。
需要显式的指定目录，pg_resetwal不会使用环境变量PGDATA。
参数-f表示强制执行pg_resetwal。