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 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.
-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. 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.
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.
