控制文件
控制文件记录了数据库运行时的一些信息，如数据库OID,是否为打开状态，预写日志的位置、检查点的信息等。
控制文件位置默认保存在$PGDATA/global目录下，pg_control 这个就是。
控制文件内容
[postgres@iZwz909xeqcc7ouqk8528zZ 16]$ pg_controldata pg_control version number: 1300 Catalog version number: 202307071 Database system identifier: 7315606169607793000 Database cluster state: in production pg_control last modified: Sat 23 Dec 2023 05:38:47 PM CST Latest checkpoint location: 0/1953A80 Latest checkpoint's REDO location: 0/1953A48 Latest checkpoint's REDO WAL file: 000000010000000000000001 # 这个是checkpoint时对应的最先的redo文件 Latest checkpoint's TimeLineID: 1 Latest checkpoint's PrevTimeLineID: 1 Latest checkpoint's full_page_writes: on Latest checkpoint's NextXID: 0:749 Latest checkpoint's NextOID: 24576 Latest checkpoint's NextMultiXactId: 1 Latest checkpoint's NextMultiOffset: 0 Latest checkpoint's oldestXID: 723 Latest checkpoint's oldestXID's DB: 1 Latest checkpoint's oldestActiveXID: 749 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: Sat 23 Dec 2023 05:38:46 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: 512cda2addebfe9037f9dd577edcd7a2709cf6c430bd2f600874d501a605b2c0 [postgres@iZwz909xeqcc7ouqk8528zZ 16]$