pg_control丢失/损坏处理

-l ：设置下一个wal日志名
可以通过 $PGDATA/pg_wal 目录中查找数值最新的WAL段的文件名+1

[postgres@localhost pg_wal]$ ls
00000001000000000000008E  archive_status

-l 00000001000000000000008F

-m：设置下一个和最旧的事务ID
mxid1：下一个多事务ID的安全值可以通过在 $PGDATA/pg_multixact/offsets目录中查找数值最大的文件名+1，然后乘以65536（0×10000）来确定。
mxid2：最旧的事务ID的安全值可以通过$PGDATA/pg_multixact/offsets目录中数字最小的文件名+1，乘以65536（0×10000）来确定。文件名是十六进制

[postgres@localhost pg_wal]$ cd ../pg_multixact
[postgres@localhost pg_multixact]$ ls
members  offsets
[postgres@localhost pg_multixact]$ cd offsets/
[postgres@localhost offsets]$ ls
0000

-m 0x10000,0x10000

-O：设置下一个多事务处理偏移量
安全值可以通过在 $PGDATA/pg_multixact/members 目录中查找数值最大的文件名，+1，然后乘以52352（0xCC80）来确定。文件名为十六进制

[postgres@localhost members]$ ls
0000

-O 0xCC80

-x：设置下一个事务ID
安全值可以通过在$PGDATA/pg_xact目录中查找数值最大的文件名，+1，然后乘以1048576（0×100000）来确定。请注意，文件名是十六进制

[postgres@localhost pg_xact]$ ls -ltr
total 504
-rw------- 1 postgres postgres 262144 Mar  8 01:53 0000
-rw------- 1 postgres postgres 253952 Mar  9 10:54 0001

-x 0x200000

删除postmaster.pid文件
如果正常关闭库,该文件会被自动删除,异常关闭的才需要处理

[postgres@localhost pg_wal]$ pg_resetwal -l 00000001000000000000008F -m 0x10000,0x10000 -O 0xCC80 -x 0x200000 -f $PGDATA
pg_resetwal: error: lock file "postmaster.pid" exists
pg_resetwal: hint: Is a server running?  If not, delete the lock file and try again.
[postgres@localhost pg_wal]$ cd ../
[postgres@localhost data]$ ls -l postmaster.pid
-rw------- 1 postgres postgres 75 Mar  9 11:02 postmaster.pid
[postgres@localhost data]$ rm -rf postmaster.pid

touch pg_control文件

[postgres@localhost data]$ pg_resetwal -l 00000001000000000000008F -m 0x10000,0x10000 -O 0xCC80 -x 0x200000 -f $PGDATA
pg_resetwal: error: could not open file "global/pg_control" for reading: No such file or directory
pg_resetwal: hint: If you are sure the data directory path is correct, execute
  touch global/pg_control
and try again.
[postgres@localhost data]$ touch global/pg_control

重建pg_control

[postgres@localhost data]$ pg_resetwal -l 00000001000000000000008F -m 0x10000,0x10000 -O 0xCC80 -x 0x200000 -f $PGDATA
pg_resetwal: warning: pg_control exists but is broken or wrong version; ignoring it
Write-ahead log reset
[postgres@localhost data]$ pg_ctl start
waiting for server to start....
 done
server started