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pg_waldump(1)            PostgreSQL 12.3 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 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.


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 29.5



PostgreSQL 12.3                      2020                        pg_waldump(1)

postgresql 12.3 - Generated Mon May 25 14:49:09 CDT 2020
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