The catalog pg_cast stores data type conversion paths,
both built-in paths and those defined with CREATE CAST.
Table 43-8. pg_cast Columns
| Name | Type | References | Description |
|---|
| castsource | oid | pg_type.oid | OID of the source data type |
| casttarget | oid | pg_type.oid | OID of the target data type |
| castfunc | oid | pg_proc.oid | The OID of the function to use to perform this cast. Zero is
stored if the data types are binary compatible (that is, no
run-time operation is needed to perform the cast).
|
| castcontext | char | | Indicates what contexts the cast may be invoked in.
e means only as an explicit cast (using
CAST, ::, or function-call syntax).
a means implicitly in assignment
to a target column, as well as explicitly.
i means implicitly in expressions, as well as the
other cases.
|