Fix FK constraint where index and constraint column order differ

The code for finding the constraint index was expecting the index
columns to be in the same order as the constraint columns. This
patch changes the check to require all columns be present independent
of the order.

Fixes #7226

(cherry picked from commit 887aed9)

.unreleased/pr_7229

@@ -0,0 +1 @@
+Fixes: #7229 Fix foreign key constraints where index and constraint column order differ

src/foreign_key.c

@@ -547,23 +547,32 @@ get_fk_index(Relation rel, int nkeys, AttrNumber *confkeys)
 	{
 		Oid indexoid = lfirst_oid(lc);
 		Relation indexrel = index_open(indexoid, AccessShareLock);
-		bool match = true;
 
 		if (!indexrel->rd_index->indisunique || indexrel->rd_index->indnkeyatts != nkeys)
 		{
 			index_close(indexrel, AccessShareLock);
 			continue;
 		}
 
+		Bitmapset *con_keys = NULL;
+		Bitmapset *ind_keys = NULL;
+
 		for (int i = 0; i < nkeys; i++)
 		{
-			if (indexrel->rd_index->indkey.values[i] != confkeys[i])
-			{
-				match = false;
-			}
+			/*
+			 * Since ordering of the constraint definition and index definition can differ,
+			 * we need to check that all the columns in the constraint are present in the index
+			 */
+			con_keys = bms_add_member(con_keys, confkeys[i]);
+			ind_keys = bms_add_member(ind_keys, indexrel->rd_index->indkey.values[i]);
 		}
 
+		bool match = bms_equal(con_keys, ind_keys);
+
 		index_close(indexrel, AccessShareLock);
+		bms_free(con_keys);
+		bms_free(ind_keys);
+
 		if (match)
 		{
 			return indexoid;

tsl/test/expected/foreign_keys.out

@@ -986,3 +986,14 @@ EXPLAIN (analyze, costs off, timing off, summary off) SELECT * FROM ht;
 (4 rows)
 
 ROLLBACK;
+-- #7226
+-- test multi-column fk constraint where constraint column order is different from index column order
+CREATE TABLE i7226(time timestamptz, device_id int, PRIMARY KEY (device_id, time));
+SELECT create_hypertable('i7226', 'time');
+  create_hypertable  
+---------------------
+ (15,public,i7226,t)
+(1 row)
+
+CREATE TABLE i7226_valid(time timestamptz NOT NULL,device_id int NOT NULL, FOREIGN KEY(time, device_id) REFERENCES i7226(time, device_id));
+INSERT INTO i7226 VALUES ('2024-08-29 12:00:00+00', 1);

tsl/test/sql/foreign_keys.sql

@@ -629,3 +629,11 @@ SELECT * FROM ht;
 EXPLAIN (analyze, costs off, timing off, summary off) SELECT * FROM ht;
 ROLLBACK;
 
+-- #7226
+-- test multi-column fk constraint where constraint column order is different from index column order
+CREATE TABLE i7226(time timestamptz, device_id int, PRIMARY KEY (device_id, time));
+SELECT create_hypertable('i7226', 'time');
+
+CREATE TABLE i7226_valid(time timestamptz NOT NULL,device_id int NOT NULL, FOREIGN KEY(time, device_id) REFERENCES i7226(time, device_id));
+INSERT INTO i7226 VALUES ('2024-08-29 12:00:00+00', 1);
+