pg_attribute_encoding

The pg_attribute_encoding system catalog table contains column storage information.

column	type	modifers	storage	description
attrelid	oid	not null	plain	Foreign key to pg_attribute.attrelid
attnum	smallint	not null	plain	Foreign key to pg_attribute.attnum
filenum	smallint	not null	plain	Shorthand for the file range assigned to the column
lastrownums	bigint		extended	The last row number of each segfile when this attribute is added.
attoptions	text [ ]		extended	The options

For a column with filenum = f, the column files on disk use the suffix (f - 1)*128 to f*128 - 1. For example:

• Column with filenum = 1 has files relfilenode, relfilenode.1 .. relfilenode.127.
• Column with filenum = 2 has files relfilenode.128, relfilenode.129 .. relfilenode.255.
• Column with filenum = 3 has files relfilenode.256, relfilenode.257 .. relfilenode.383.

Parent topic: System Catalogs Definitions