PostgreSQL array of elements that each are a foreign key

It may soon be possible to do this: https://commitfest.postgresql.org/17/1252/ - Mark Rofail has been doing some excellent work on this patch!

The patch will (once complete) allow

CREATE TABLE PKTABLEFORARRAY (    ptest1 float8 PRIMARY KEY,    ptest2 text);CREATE TABLE FKTABLEFORARRAY (    ftest1 int[],    FOREIGN KEY (EACH ELEMENT OF ftest1) REFERENCES PKTABLEFORARRAY,    ftest2 int);

However, author currently needs help to rebase the patch (beyond my own ability) so anyone reading this who knows Postgres internals please help if you can.

No, this is not possible.

PostgreSQL is a relational DBMS, operating most efficiently on properly normalized data models. Arrays are - by definition, they are ordered sets - not relational data structures and the SQL standard therefore does not support defining foreign keys on array elements, and neither does PostgreSQL.

You can, however, build a perfectly fine database with array elements linking to primary keys in other tables. Those array elements, however, can not be declared to be foreign keys and the DBMS will therefore not maintain referential integrity.