【赵渝强老师】PostgreSQL的控制文件

PostgreSQL数据库的物理存储结构主要是指硬盘上存储的文件，包括：数据文件、日志文件、参数文件、控制文件、WAL预写日志文件等等。
下面重点讨论一下PostgreSQL的控制文件。视频讲解如下：
https://www.bilibili.com/video/BV1Vysse7Edq/?aid=113033825354...

控制文件记录了数据库运行时的一些信息，比如数据库oid、是否是打开状态、WAL的位置、检查点的信息等等。PostgreSQL的控制文件是很重要的数据库文件。控制文件默认保存在$PGDATA/global/pg_control目录下，可以使用命令bin/pg_controldata查看控制文件的内容，具体的操作步骤如下：

（1）进入PostgreSQL的安装目录。

cd /home/postgres/training/pgsql

（2）执行命令查看控制文件的内容。

[postgres@mydb pgsql]$ bin/pg_controldata data/

# 输出的信息如下：
pg_control version number:            1300
Catalog version number:               202007201
Database system identifier:           7208875389865427015
Database cluster state:               in production
pg_control last modified:             Fri 21 Apr 2023 05:56:43 PM CST
Latest checkpoint location:           0/2000098
Latest checkpoint's REDO location:    0/2000060
Latest checkpoint's REDO WAL file:    000000010000000000000002
Latest checkpoint's TimeLineID:       1
Latest checkpoint's PrevTimeLineID:   1
Latest checkpoint's full_page_writes: on
Latest checkpoint's NextXID:          0:492
Latest checkpoint's NextOID:          24576
Latest checkpoint's NextMultiXactId:  1
Latest checkpoint's NextMultiOffset:  0
Latest checkpoint's oldestXID:        478
Latest checkpoint's oldestXID's DB:   1
Latest checkpoint's oldestActiveXID:  492
Latest checkpoint's oldestMultiXid:   1
Latest checkpoint's oldestMulti's DB: 1
Latest checkpoint's oldestCommitTsXid:0
Latest checkpoint's newestCommitTsXid:0
Time of latest checkpoint:            Fri 21 Apr 2023 05:56:43 PM CST
Fake LSN counter for unlogged rels:   0/3E8
Minimum recovery ending location:     0/0
Min recovery ending loc's timeline:   0
Backup start location:                0/0
Backup end location:                  0/0
End-of-backup record required:        no
wal_level setting:                    replica
wal_log_hints setting:                off
max_connections setting:              100
max_worker_processes setting:         8
max_wal_senders setting:              10
max_prepared_xacts setting:           0
max_locks_per_xact setting:           64
track_commit_timestamp setting:       off
Maximum data alignment:               8
Database block size:                  8192
Blocks per segment of large relation: 131072
WAL block size:                       8192
Bytes per WAL segment:                16777216
Maximum length of identifiers:        64
Maximum columns in an index:          32
Maximum size of a TOAST chunk:        1996
Size of a large-object chunk:         2048
Date/time type storage:               64-bit integers
Float8 argument passing:              by value
Data page checksum version:           0
Mock authentication nonce:            
7fda27a3058cbfb6cde2be36c58d96a33787abb79d40f4c07d36b932460def9b