PostgreSQL 8.2.6 Documentation | ||||
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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 43-6. pg_attrdef Columns
Name | Type | References | Description |
---|---|---|---|
adrelid | oid | pg_class .oid | The table this column belongs to |
adnum | int2 | pg_attribute .attnum | The number of the column |
adbin | text | 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.