The pg_conversion system catalog table describes the available encoding conversion procedures as defined by CREATE CONVERSION.

Table 1. pg_catalog.pg_conversion

column type references description
conname name   Conversion name (unique within a namespace).
connamespace oid pg_namespace.oid The OID of the namespace (schema) that contains this conversion.
conowner oid pg_authid.oid Owner of the conversion.
conforencoding integer   Source encoding ID.
contoencoding integer   Destination encoding ID.
conproc regproc pg_proc.oid Conversion procedure.
condefault boolean   True if this is the default conversion.