pg_waldump — display a human-readable rendering of the write-ahead log of a PostgreSQL database cluster
pg_waldump
[option
...] [startseg
[endseg
]]
pg_waldump
displays the write-ahead log (WAL) and is mainly useful for debugging or educational purposes.
This utility can only be run by the user who installed the server, because it requires read-only access to the data directory.
The following command-line options control the location and format of the output:
startseg
Start reading at the specified log segment file. This implicitly determines the path in which files will be searched for, and the timeline to use.
endseg
Stop after reading the specified log segment file.
-b
--bkp-details
Output detailed information about backup blocks.
-e end
--end=end
Stop reading at the specified WAL location, instead of reading to the end of the log stream.
-f
--follow
After reaching the end of valid WAL, keep polling once per second for new WAL to appear.
-n limit
--limit=limit
Display the specified number of records, then stop.
-p path
--path=path
Specifies a directory to search for log segment files or a directory with a pg_wal
subdirectory that contains such files. The default is to search in the current directory, the pg_wal
subdirectory of the current directory, and the pg_wal
subdirectory of PGDATA
.
-r rmgr
--rmgr=rmgr
Only display records generated by the specified resource manager. If list
is passed as name, print a list of valid resource manager names, and exit.
-s start
--start=start
WAL location at which to start reading. The default is to start reading the first valid log record found in the earliest file found.
-t timeline
--timeline=timeline
Timeline from which to read log records. The default is to use the value in startseg
, if that is specified; otherwise, the default is 1.
-V
--version
Print the pg_waldump version and exit.
-x xid
--xid=xid
Only display records marked with the given transaction ID.
-z
--stats[=record]
Display summary statistics (number and size of records and full-page images) instead of individual records. Optionally generate statistics per-record instead of per-rmgr.
-?
--help
Show help about pg_waldump command line arguments, and exit.
PGDATA
Data directory; see also the -p
option.
PG_COLOR
Specifies whether to use color in diagnostic messages. Possible values are always
, auto
and never
.
Can give wrong results when the server is running.
Only the specified timeline is displayed (or the default, if none is specified). Records in other timelines are ignored.
pg_waldump cannot read WAL files with suffix .partial
. If those files need to be read, .partial
suffix needs to be removed from the file name.
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