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)