> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/appendixes/contrib/pglogicalinspect.md).

# F.28. pg\_logicalinspect — logical decoding components inspection \#

[F.28.1. Functions](#PGLOGICALINSPECT-FUNCS)

[F.28.2. Author](#PGLOGICALINSPECT-AUTHOR)

The `pg_logicalinspect` module provides SQL functions that allow you to inspect the contents of logical decoding components. It allows the inspection of serialized logical snapshots of a running PostgreSQL database cluster, which is useful for debugging or educational purposes.

By default, use of these functions is restricted to superusers and members of the `pg_read_server_files` role. Access may be granted by superusers to others using `GRANT`.

## F.28.1. Functions [#](#PGLOGICALINSPECT-FUNCS)

`pg_get_logical_snapshot_meta(filename text) returns record` [#](#PGLOGICALINSPECT-FUNCS-PG-GET-LOGICAL-SNAPSHOT-META) : Gets logical snapshot metadata about a snapshot file that is located in the server's `pg_logical/snapshots` directory. The *`filename`* argument represents the snapshot file name. For example:

````
```

postgres=# SELECT * FROM pg_ls_logicalsnapdir();
-[ RECORD 1 ]+-----------------------
name         | 0-40796E18.snap
size         | 152
modification | 2024-08-14 16:36:32+00

postgres=# SELECT * FROM pg_get_logical_snapshot_meta('0-40796E18.snap');
-[ RECORD 1 ]--------
magic    | 1369563137
checksum | 1028045905
version  | 6

postgres=# SELECT ss.name, meta.* FROM pg_ls_logicalsnapdir() AS ss,
pg_get_logical_snapshot_meta(ss.name) AS meta;
-[ RECORD 1 ]-------------
name     | 0-40796E18.snap
magic    | 1369563137
checksum | 1028045905
version  | 6
```

If *`filename`* does not match a snapshot file, the
function raises an error.
````

`pg_get_logical_snapshot_info(filename text) returns record` [#](#PGLOGICALINSPECT-FUNCS-PG-GET-LOGICAL-SNAPSHOT-INFO) : Gets logical snapshot information about a snapshot file that is located in the server's `pg_logical/snapshots` directory. The *`filename`* argument represents the snapshot file name. For example:

````
```

postgres=# SELECT * FROM pg_ls_logicalsnapdir();
-[ RECORD 1 ]+-----------------------
name         | 0-40796E18.snap
size         | 152
modification | 2024-08-14 16:36:32+00

postgres=# SELECT * FROM pg_get_logical_snapshot_info('0-40796E18.snap');
-[ RECORD 1 ]------------+-----------
state                    | consistent
xmin                     | 751
xmax                     | 751
start_decoding_at        | 0/40796AF8
two_phase_at             | 0/40796AF8
initial_xmin_horizon     | 0
building_full_snapshot   | f
in_slot_creation         | f
last_serialized_snapshot | 0/0
next_phase_at            | 0
committed_count          | 0
committed_xip            |
catchange_count          | 2
catchange_xip            | {751,752}

postgres=# SELECT ss.name, info.* FROM pg_ls_logicalsnapdir() AS ss,
pg_get_logical_snapshot_info(ss.name) AS info;
-[ RECORD 1 ]------------+----------------
name                     | 0-40796E18.snap
state                    | consistent
xmin                     | 751
xmax                     | 751
start_decoding_at        | 0/40796AF8
two_phase_at             | 0/40796AF8
initial_xmin_horizon     | 0
building_full_snapshot   | f
in_slot_creation         | f
last_serialized_snapshot | 0/0
next_phase_at            | 0
committed_count          | 0
committed_xip            |
catchange_count          | 2
catchange_xip            | {751,752}
```

If *`filename`* does not match a snapshot file, the
function raises an error.
````

## F.28.2. Author [#](#PGLOGICALINSPECT-AUTHOR)

Bertrand Drouvot `<bertranddrouvot.pg@gmail.com>`

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/pglogicalinspect.html)（英文原文，待翻譯）


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