Add temporal FOREIGN KEY contraints

Add PERIOD clause to foreign key constraint definitions.  This is
supported for range and multirange types.  Temporal foreign keys check
for range containment instead of equality.

This feature matches the behavior of the SQL standard temporal foreign
keys, but it works on PostgreSQL's native ranges instead of SQL's
"periods", which don't exist in PostgreSQL (yet).

Reference actions ON {UPDATE,DELETE} {CASCADE,SET NULL,SET DEFAULT}
are not supported yet.

Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com

1 files changed, 28 insertions, 0 deletions

diff --git a/contrib/btree_gist/sql/without_overlaps.sql b/contrib/btree_gist/sql/without_overlaps.sql
index 433c609ab22..b1b581fcabc 100644
--- a/contrib/btree_gist/sql/without_overlaps.sql
+++ b/contrib/btree_gist/sql/without_overlaps.sql
@@ -23,3 +23,31 @@ INSERT INTO temporal_rng VALUES
 -- should fail:
 INSERT INTO temporal_rng VALUES
   (1, '[2000-06-01,2001-01-01)');
+
+-- Foreign key
+CREATE TABLE temporal_fk_rng2rng (
+  id integer,
+  valid_at daterange,
+  parent_id integer,
+  CONSTRAINT temporal_fk_rng2rng_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+  CONSTRAINT temporal_fk_rng2rng_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+    REFERENCES temporal_rng (id, PERIOD valid_at)
+);
+\d temporal_fk_rng2rng
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_fk_rng2rng_fk';
+
+-- okay
+INSERT INTO temporal_fk_rng2rng VALUES
+  (1, '[2000-01-01,2001-01-01)', 1);
+-- okay spanning two parent records:
+INSERT INTO temporal_fk_rng2rng VALUES
+  (2, '[2000-01-01,2002-01-01)', 1);
+-- key is missing
+INSERT INTO temporal_fk_rng2rng VALUES
+  (3, '[2000-01-01,2001-01-01)', 3);
+-- key exist but is outside range
+INSERT INTO temporal_fk_rng2rng VALUES
+  (4, '[2001-01-01,2002-01-01)', 2);
+-- key exist but is partly outside range
+INSERT INTO temporal_fk_rng2rng VALUES
+  (5, '[2000-01-01,2002-01-01)', 2);