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pg_walsummary
pg_walsummary — print contents of WAL summary files
Reading PostgreSQL 18.6.
Description
pg_walsummary — print contents of WAL summary files
- Documented executable
- pg_walsummary
- Executable version
- 18.6
- Reference inventory
- Server applications
- Option definition groups
- 4
Usage
pg_walsummary [ option ...] [ file ...]Documented options
| Option and arguments | Description |
|---|---|
| -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. |
Manual definition
pg_walsummary
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 in 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_walsummaryprints 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, pg_combinebackupDocumentation and source
Source build
- Version
- 18.6
- Build
- https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
- Source fingerprint
ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8
Compare versions
PostgreSQL 16 → 17: added.
--- PostgreSQL 16
+++ PostgreSQL 17
@@ -1 +1,40 @@
-Not recorded in this version
+{
+ "environment": [],
+ "options": [
+ {
+ "description": "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.",
+ "names": [
+ "-i",
+ "--individual"
+ ],
+ "signature": "-i --individual"
+ },
+ {
+ "description": "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.",
+ "names": [
+ "-q",
+ "--quiet"
+ ],
+ "signature": "-q --quiet"
+ },
+ {
+ "description": "Display version information, then exit.",
+ "names": [
+ "-V",
+ "--version"
+ ],
+ "signature": "-V --version"
+ },
+ {
+ "description": "Shows help about pg_walsummary command line arguments, and exits.",
+ "names": [
+ "-?",
+ "--help"
+ ],
+ "signature": "-? --help"
+ }
+ ],
+ "synopsis": [
+ "pg_walsummary [ option ...] [ file ...]"
+ ]
+}Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.
Related entries
Export JSON · Back to Command-line Tools · Recorded in PostgreSQL 17 through 20; the first sample is not necessarily its introduction.