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PG_WALDUMP(1)		 PostgreSQL 17.5 Documentation		 PG_WALDUMP(1)

NAME
       pg_waldump - display a human-readable rendering of the write-ahead log
       of a PostgreSQL database	cluster

SYNOPSIS

       pg_waldump [option...] [startseg	[endseg]]

DESCRIPTION
       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.

OPTIONS
       The following command-line options control the location and format of
       the output:

       startseg
	   Start reading at the	specified WAL 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 WAL	segment	file.

       -b
       --bkp-details
	   Output detailed information about backup blocks.

       -B block
       --block=block
	   Only	display	records	that modify the	given block. The relation must
	   also	be provided with --relation or -R.

       -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.

       -F fork
       --fork=fork
	   Only	display	records	that modify blocks in the given	fork. The
	   valid values	are main for the main fork, fsm	for the	free space
	   map,	vm for the visibility map, and init for	the init fork.

       -n limit
       --limit=limit
	   Display the specified number	of records, then stop.

       -p path
       --path=path
	   Specifies a directory to search for WAL 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.

       -q
       --quiet
	   Do not print	any output, except for errors. This option can be
	   useful when you want	to know	whether	a range	of WAL records can be
	   successfully	parsed but don't care about the	record contents.

       -r rmgr
       --rmgr=rmgr
	   Only	display	records	generated by the specified resource manager.
	   You can specify the option multiple times to	select multiple
	   resource managers. If list is passed	as name, print a list of valid
	   resource manager names, and exit.

	   Extensions may define custom	resource managers, but pg_waldump does
	   not load the	extension module and therefore does not	recognize
	   custom resource managers by name. Instead, you can specify the
	   custom resource managers as custom### where ### is the three-digit
	   resource manager ID.	Names of this form will	always be considered
	   valid.

       -R tblspc/db/rel
       --relation=tblspc/db/rel
	   Only	display	records	that modify blocks in the given	relation. The
	   relation is specified with tablespace OID, database OID, and
	   relfilenode separated by slashes, for example 1234/12345/12345.
	   This	is the same format used	for relations in the program's output.

       -s start
       --start=start
	   WAL location	at which to start reading. The default is to start
	   reading the first valid WAL record found in the earliest file
	   found.

       -t timeline
       --timeline=timeline
	   Timeline from which to read WAL records. The	default	is to use the
	   value in startseg, if that is specified; otherwise, the default is
	   1. The value	can be specified in decimal or hexadecimal, for
	   example 17 or 0x11.

       -V
       --version
	   Print the pg_waldump	version	and exit.

       -w
       --fullpage
	   Only	display	records	that include full page images.

       -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.

	   If pg_waldump is terminated by signal SIGINT	(Control+C), the
	   summary of the statistics computed is displayed up to the
	   termination point. This operation is	not supported on Windows.

       --save-fullpage=save_path
	   Save	full page images found in the WAL records to the save_path
	   directory. The images saved are subject to the same filtering and
	   limiting criteria as	the records displayed.

	   The full page images	are saved with the following file name format:
	   TIMELINE-LSN.RELTABLESPACE.DATOID.RELNODE.BLKNO_FORK	The file names
	   are composed	of the following parts:
	   +---------------+----------------------------+
	   | Component	   | Description		|
	   +---------------+----------------------------+
	   | TIMELINE	   | The timeline of the WAL	|
	   |		   | segment file where	the	|
	   |		   | record			|
	   |		   |		  is located	|
	   |		   | formatted as one		|
	   |		   | 8-character hexadecimal	|
	   |		   | number			|
	   |		   |		  %08X		|
	   +---------------+----------------------------+
	   | LSN	   | The LSN of	the record with	|
	   |		   | this image,		|
	   |		   |		  formatted as	|
	   |		   | two 8-character		|
	   |		   | hexadecimal numbers	|
	   |		   |		  %08X-%08X	|
	   +---------------+----------------------------+
	   | RELTABLESPACE | tablespace	OID of the	|
	   |		   | block			|
	   +---------------+----------------------------+
	   | DATOID	   | database OID of the block	|
	   +---------------+----------------------------+
	   | RELNODE	   | filenode of the block	|
	   +---------------+----------------------------+
	   | BLKNO	   | block number of the block	|
	   +---------------+----------------------------+
	   | FORK	   | The name of the fork the	|
	   |		   | full page image came from,	|
	   |		   | such as			|
	   |		   |		  main,	fsm,	|
	   |		   |		  vm, or init.	|
	   +---------------+----------------------------+

       -?
       --help
	   Show	help about pg_waldump command line arguments, and exit.

ENVIRONMENT
       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.

NOTES
       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.

SEE ALSO
       Section 28.6

PostgreSQL 17.5			     2025			 PG_WALDUMP(1)

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