NAME

       pg_walsummary - print contents of WAL summary files

SYNOPSIS

       pg_walsummary [option...] [file...]

DESCRIPTION

       pg_walsummary is used to print the contents of WAL summary files. These binary files are found with the
       pg_wal/summaries subdirectory of the data directory, and can be converted to text using this tool. This
       is not ordinarily necessary, since WAL summary files primarily exist to support incremental backup, but
       it may be useful for debugging purposes.

       A WAL summary file is indexed by tablespace OID, relation OID, and relation fork. For each relation fork,
       it stores the list of blocks that were modified by WAL within the range summarized in the file. It can
       also store a "limit block," which is 0 if the relation fork was created or truncated within the relevant
       WAL range, and otherwise the shortest length to which the relation fork was truncated. If the relation
       fork was not created, deleted, or truncated within the relevant WAL range, the limit block is undefined
       or infinite and will not be printed by this tool.

OPTIONS

       -i
       --individual
           By default, pg_walsummary prints one line of output for each range of one or more consecutive
           modified blocks. This can make the output a lot briefer, since a relation where all blocks from 0
           through 999 were modified will produce only one line of output rather than 1000 separate lines. This
           option requests a separate line of output for every modified block.

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

       -V
       --version
           Display version information, then exit.

       -?
       --help
           Shows help about pg_walsummary command line arguments, and exits.

ENVIRONMENT

       The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values
       are always, auto and never.

SEE ALSO

       pg_basebackup(1), pg_combinebackup(1)

PostgreSQL 17.9                                       2026                                      PG_WALSUMMARY(1)