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52.6. pg_attrdef

The catalog pg_attrdef stores column default values. The main information about columns is stored in pg_attribute (see below). Only columns that explicitly specify a default value (when the table is created or the column is added) will have an entry here.

Table 52.6. pg_attrdef Columns

Name Type References Description

oid

oid

Row identifier (hidden attribute; must be explicitly selected)

adrelid

oid

pg_class.oid

The table this column belongs to

adnum

int2

pg_attribute.attnum

The number of the column

adbin

pg_node_tree

The internal representation of the column default value

adsrc

text

A human-readable representation of the default value

+

The adsrc field is historical, and is best not used, because it does not track outside changes that might affect the representation of the default value. Reverse-compiling the adbin field (with pg_get_expr for example) is a better way to display the default value.


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52.7. pg_attribute

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