Fix issue with adding foreign key constraint in hte presence of OSM chunks

We cannot create a foreign key constraint on a foreign table.

Author: gayyappan

src/foreign_key.c

@@ -80,21 +80,24 @@ propagate_fk(Relation ht_rel, HeapTuple fk_tuple, List *chunks)
 	foreach (lc, chunks)
 	{
 		Chunk *chunk = lfirst(lc);
-		clone_constraint_on_chunk(chunk,
-								  ht_rel,
-								  fk,
-								  numfks,
-								  conkey,
-								  confkey,
-								  conpfeqop,
-								  conppeqop,
-								  conffeqop,
+		if (!chunk->fd.osm_chunk)
+		{
+			clone_constraint_on_chunk(chunk,
+									  ht_rel,
+									  fk,
+									  numfks,
+									  conkey,
+									  confkey,
+									  conpfeqop,
+									  conppeqop,
+									  conffeqop,
 #if PG15_GE
-								  numfkdelsetcols,
-								  confdelsetcols,
+									  numfkdelsetcols,
+									  confdelsetcols,
 #endif
-								  parentDelTrigger,
-								  parentUpdTrigger);
+									  parentDelTrigger,
+									  parentUpdTrigger);
+		}
 	}
 }
 

tsl/test/sql/chunk_utils_internal.sql

@@ -651,6 +651,27 @@ DROP INDEX hyper_constr_mid_idx;
 
 \i include/chunk_utils_internal_orderedappend.sql
 
+--TEST hypertable with foreign key into it
+\c :TEST_DBNAME :ROLE_4
+CREATE TABLE hyper_fk(ts timestamptz primary key, device text, value float);
+SELECT table_name FROM create_hypertable('hyper_fk', 'ts');
+
+INSERT INTO hyper_fk(ts, device, value) VALUES ('2020-01-01 00:00:00', 'd1', 1.0);
+\c postgres_fdw_db :ROLE_4
+CREATE TABLE fdw_hyper_fk(ts timestamptz NOT NULL, device text, value float);
+INSERT INTO fdw_hyper_fk VALUES( '2021-05-05 00:00', 'd2', 2.0);
+
+\c :TEST_DBNAME :ROLE_4
+-- this is a stand-in for the OSM table
+CREATE FOREIGN TABLE child_hyper_fk
+(ts timestamptz NOT NULL, device text, value float)
+ SERVER s3_server OPTIONS ( schema_name 'public', table_name 'fdw_hyper_fk');
+SELECT _timescaledb_functions.attach_osm_table_chunk('hyper_fk', 'child_hyper_fk');
+
+--create table with fk into hypertable
+CREATE TABLE event(ts timestamptz REFERENCES hyper_fk(ts) , info text);
+INSERT INTO event VALUES( '2021-05-05 00:00' , 'osm_chunk_ts');
+
 -- clean up databases created
 \c :TEST_DBNAME :ROLE_SUPERUSER
 DROP DATABASE postgres_fdw_db WITH (FORCE);