java - 如何通过java读取pg_xlog目录下的WAL文件

Question

我正在尝试读取 postgresql 的 WAL 文件，任何人都可以告诉我该怎么做 n WAL 二进制文件中使用了哪种类型的二进制编码

Answer 1

使用 pg_xlogdump 读取 WAL 文件(此 contrib 程序已添加到 PG 9.3 版本 - PG 9.3 released doc)

This utility can only be run by the user who installed the server, because it requires read-only access to the data directory.

pg_xlogdump --help
pg_xlogdump decodes and displays PostgreSQL transaction logs for debugging.

Usage:
  pg_xlogdump [OPTION]... [STARTSEG [ENDSEG]]

Options:
  -b, --bkp-details      output detailed information about backup blocks
  -e, --end=RECPTR       stop reading at log position RECPTR
  -f, --follow           keep retrying after reaching end of WAL
  -n, --limit=N          number of records to display
  -p, --path=PATH        directory in which to find log segment files
                         (default: ./pg_xlog)
  -r, --rmgr=RMGR        only show records generated by resource manager RMGR
                         use --rmgr=list to list valid resource manager names
  -s, --start=RECPTR     start reading at log position RECPTR
  -t, --timeline=TLI     timeline from which to read log records
                         (default: 1 or the value used in STARTSEG)
  -V, --version          output version information, then exit
  -x, --xid=XID          only show records with TransactionId XID
  -z, --stats[=record]   show statistics instead of records
                         (optionally, show per-record statistics)
  -?, --help             show this help, then exit

例如:pg_xlogdump 000000010000005A00000096

PostgreSQL Document或 this blog