'\" t
.\"     Title: pg_walsummary
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2025
.\"    Manual: PostgreSQL 18.0 Documentation
.\"    Source: PostgreSQL 18.0
.\"  Language: English
.\"
.TH "PG_WALSUMMARY" "1" "2025" "PostgreSQL 18.0" "PostgreSQL 18.0 Documentation"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
pg_walsummary \- print contents of WAL summary files
.SH "SYNOPSIS"
.HP \w'\fBpg_walsummary\fR\ 'u
\fBpg_walsummary\fR [\fIoption\fR...] [\fIfile\fR...]
.SH "DESCRIPTION"
.PP
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\&.
.PP
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\&.
.SH "OPTIONS"
.PP
.PP
\fB\-i\fR
.br
\fB\-\-individual\fR
.RS 4
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\&.
.RE
.PP
\fB\-q\fR
.br
\fB\-\-quiet\fR
.RS 4
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\*(Aqt care about the contents\&.
.RE
.PP
\fB\-V\fR
.br
\fB\-\-version\fR
.RS 4
Display version information, then exit\&.
.RE
.PP
\fB\-?\fR
.br
\fB\-\-help\fR
.RS 4
Shows help about
pg_walsummary
command line arguments, and exits\&.
.RE
.SH "ENVIRONMENT"
.PP
The environment variable
\fBPG_COLOR\fR
specifies whether to use color in diagnostic messages\&. Possible values are
always,
auto
and
never\&.
.SH "SEE ALSO"
\fBpg_basebackup\fR(1), \fBpg_combinebackup\fR(1)