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Updated on 2022-08-16 GMT+08:00
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PG_LARGEOBJECT

PG_LARGEOBJECT records 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).

It is accessible only to users with system administrator rights.

Table 1 PG_LARGEOBJECT columns

Name

Type

Reference

Description

loid

oid

PG_LARGEOBJECT_METADATA.oid

Identifier of the large object that includes this page

pageno

integer

-

Page number of this page within its large object (counting from zero)

data

bytea

-

Actual data stored in the large object. This will never be more than LOBLKSIZE bytes and might be less.

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 are read as zeroes.

Parent topic: System Catalogs