Comunque, in questo momento ho un commento sulla mailing list di PostgreSQL .
/*
* Decide whether to create an array type over the relation's rowtype. We
* do not create any array types for system catalogs (ie, those made
* during initdb). We do not create them where the use of a relation as
* such is an implementation detail: toast tables, sequences and indexes.
*/
if (IsUnderPostmaster && (relkind == RELKIND_RELATION ||
relkind == RELKIND_VIEW ||
relkind == RELKIND_MATVIEW ||
relkind == RELKIND_FOREIGN_TABLE ||
relkind == RELKIND_COMPOSITE_TYPE))
new_array_oid = AssignTypeArrayOid();