Re: [HACKERS] GSoC 2017: Foreign Key Arrays

1) MATCH FULL does not seem to care about NULLS in arrays. In the example below I expected both inserts into the referring table to fail.

CREATE TABLE t (x int, y int, PRIMARY KEY (x, y));
CREATE TABLE fk (x int, ys int[], FOREIGN KEY (x, EACH ELEMENT OF ys) REFERENCES t MATCH FULL);
INSERT INTO t VALUES (10, 1);
INSERT INTO fk VALUES (10, '{1,NULL}');
INSERT INTO fk VALUES (NULL, '{1}');

CREATE TABLE
CREATE TABLE
INSERT 0 1
INSERT 0 1
ERROR:  insert or update on table "fk" violates foreign key constraint "fk_x_fkey"
DETAIL:  MATCH FULL does not allow mixing of null and nonnull key values.

2) I think the code in RI_Initial_Check() would be cleaner if you used "CROSS JOIN LATERAL unnest(col)" rather than having unnest() in the target list. This way you would not need to rename all columns and the code paths for the array case could look more like the code path for the normal case.