> 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/15/internals/system-catalogs/pg_largeobject.md).

# 53.30. pg\_largeobject

## 53.30. pg\_largeobject

The catalog `pg_largeobject` holds the data making up “large objects”. A large object is identified by an OID assigned when it is created. Each large object is broken into segments or “pages” small enough to be conveniently stored as rows in `pg_largeobject`. The amount of data per page is defined to be `LOBLKSIZE` (which is currently `BLCKSZ/4`, or typically 2 kB).

Prior to PostgreSQL 9.0, there was no permission structure associated with large objects. As a result, `pg_largeobject` was publicly readable and could be used to obtain the OIDs (and contents) of all large objects in the system. This is no longer the case; use [`pg_largeobject_metadata`](/15/internals/system-catalogs/pg_largeobject_metadata.md) to obtain a list of large object OIDs.

**Table 53.30. `pg_largeobject` Columns**

| <p>Column Type</p><p>Description</p>                                                                                                                                                                                                               |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| <p><code>loid</code> <code>oid</code> (references <a href="/15/internals/system-catalogs/pg_largeobject_metadata.md"><code>pg\_largeobject\_metadata</code></a>.<code>oid</code>)</p><p>Identifier of the large object that includes this page</p> |
| <p><code>pageno</code> <code>int4</code></p><p>Page number of this page within its large object (counting from zero)</p>                                                                                                                           |
| <p><code>data</code> <code>bytea</code></p><p>Actual data stored in the large object. This will never be more than <code>LOBLKSIZE</code> bytes and might be less.</p>                                                                             |

Each row of `pg_largeobject` holds data for one page of a large object, beginning at byte offset (`pageno * LOBLKSIZE`) within the object. The implementation allows sparse storage: pages might be missing, and might be shorter than `LOBLKSIZE` bytes even if they are not the last page of the object. Missing regions within a large object read as zeroes.

***

原文：[PostgreSQL 15.19 Documentation](/15/internals/system-catalogs/pg_largeobject.md)（英文原文，待翻譯）


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