Sync FK behaviour when creating hypertable

We now allow FKs to hypertables but the initial check when creating
the hypertable was not adjusted so tables with pre-existing FKs
would not be allowed to be changed into hypertable while creating
the FK constraint afterwards succeeded.

.unreleased/pr_7301

@@ -0,0 +1 @@
+Fixes: #7301 Make foreign key behaviour for hypertables consistent

src/hypertable.c

@@ -1319,7 +1319,10 @@ hypertable_validate_constraints(Oid relid)
 	{
 		Form_pg_constraint form = (Form_pg_constraint) GETSTRUCT(tuple);
 
-		if (form->contype == CONSTRAINT_FOREIGN)
+		/*
+		 * Hypertable <-> hypertable foreign keys are not supported.
+		 */
+		if (form->contype == CONSTRAINT_FOREIGN && ts_hypertable_relid_to_id(form->conrelid) != -1)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 					 errmsg("cannot have FOREIGN KEY constraints to hypertable \"%s\"",

test/expected/create_hypertable.out

@@ -1054,7 +1054,6 @@ select * from tidrangescan_test where time > '2023-02-12 00:00:00+02:40'::timest
 (3 rows)
 
 drop table tidrangescan_test;
-\set ON_ERROR_STOP 0
 \set VERBOSITY default
 set client_min_messages = WARNING;
 -- test creating a hypertable from table referenced by a foreign key fails with
@@ -1065,6 +1064,13 @@ create table test_schema.fk_child(
   id int,
   foreign key (time, id) references test_schema.fk_parent(time, id)
 );
+select create_hypertable ('test_schema.fk_child', 'time');
+      create_hypertable      
+-----------------------------
+ (23,test_schema,fk_child,t)
+(1 row)
+
+\set ON_ERROR_STOP 0
 select create_hypertable ('test_schema.fk_parent', 'time');
 ERROR:  cannot have FOREIGN KEY constraints to hypertable "fk_parent"
 HINT:  Remove all FOREIGN KEY constraints to table "fk_parent" before making it a hypertable.
@@ -1088,8 +1094,8 @@ SELECT * FROM test.show_indexes('test') ORDER BY 1;
 SELECT * FROM show_chunks('test') ch, LATERAL test.show_indexes(ch) ORDER BY 1, 2;
                     ch                    |                         Index                          | Columns | Expr | Unique | Primary | Exclusion | Tablespace 
 ------------------------------------------+--------------------------------------------------------+---------+------+--------+---------+-----------+------------
- _timescaledb_internal._hyper_23_23_chunk | _timescaledb_internal._hyper_23_23_chunk_test_val_idx  | {val}   |      | f      | f       | f         | 
- _timescaledb_internal._hyper_23_23_chunk | _timescaledb_internal._hyper_23_23_chunk_test_time_idx | {time}  |      | f      | f       | f         | 
+ _timescaledb_internal._hyper_24_23_chunk | _timescaledb_internal._hyper_24_23_chunk_test_val_idx  | {val}   |      | f      | f       | f         | 
+ _timescaledb_internal._hyper_24_23_chunk | _timescaledb_internal._hyper_24_23_chunk_test_time_idx | {time}  |      | f      | f       | f         | 
 (2 rows)
 
 DROP TABLE test;
@@ -1112,6 +1118,6 @@ SELECT * FROM test.show_indexes('test') ORDER BY 1;
 SELECT * FROM show_chunks('test') ch, LATERAL test.show_indexes(ch) ORDER BY 1, 2;
                     ch                    |                         Index                         | Columns | Expr | Unique | Primary | Exclusion | Tablespace 
 ------------------------------------------+-------------------------------------------------------+---------+------+--------+---------+-----------+------------
- _timescaledb_internal._hyper_24_24_chunk | _timescaledb_internal._hyper_24_24_chunk_test_val_idx | {val}   |      | f      | f       | f         | 
+ _timescaledb_internal._hyper_25_24_chunk | _timescaledb_internal._hyper_25_24_chunk_test_val_idx | {val}   |      | f      | f       | f         | 
 (1 row)
 

test/sql/create_hypertable.sql

@@ -632,7 +632,6 @@ select * from tidrangescan_test where time > '2023-02-12 00:00:00+02:40'::timest
 
 drop table tidrangescan_test;
 
-\set ON_ERROR_STOP 0
 \set VERBOSITY default
 set client_min_messages = WARNING;
 -- test creating a hypertable from table referenced by a foreign key fails with
@@ -643,6 +642,8 @@ create table test_schema.fk_child(
   id int,
   foreign key (time, id) references test_schema.fk_parent(time, id)
 );
+select create_hypertable ('test_schema.fk_child', 'time');
+\set ON_ERROR_STOP 0
 select create_hypertable ('test_schema.fk_parent', 'time');
 \set ON_ERROR_STOP 1
 

tsl/test/expected/foreign_keys.out

@@ -1025,3 +1025,34 @@ 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);
+-- test foreign key constraints that have been created before hypertable conversion
+create table converted_pk(time timestamptz, id int, unique(time, id));
+create table converted_fk(time timestamptz, id int, foreign key (time, id) references converted_pk(time, id));
+select table_name FROM create_hypertable ('converted_pk', 'time');
+NOTICE:  adding not-null constraint to column "time"
+  table_name  
+--------------
+ converted_pk
+(1 row)
+
+\set ON_ERROR_STOP 0
+-- should fail
+INSERT INTO converted_fk SELECT '2020-01-01', 1;
+ERROR:  insert or update on table "converted_fk" violates foreign key constraint "converted_fk_time_id_fkey"
+\set ON_ERROR_STOP 1
+INSERT INTO converted_pk SELECT '2020-01-01 0:01', 1;
+\set ON_ERROR_STOP 0
+-- should still fail
+INSERT INTO converted_fk SELECT '2020-01-01', 1;
+ERROR:  insert or update on table "converted_fk" violates foreign key constraint "converted_fk_time_id_fkey"
+\set ON_ERROR_STOP 1
+INSERT INTO converted_fk SELECT '2020-01-01 0:01', 1;
+\set ON_ERROR_STOP 0
+-- should fail
+DELETE FROM converted_pk WHERE time = '2020-01-01 0:01';
+ERROR:  update or delete on table "_hyper_16_27_chunk" violates foreign key constraint "converted_fk_time_id_fkey1" on table "converted_fk"
+TRUNCATE converted_pk;
+ERROR:  cannot truncate a table referenced in a foreign key constraint
+\set ON_ERROR_STOP 1
+DELETE FROM converted_fk;
+DELETE FROM converted_pk WHERE time = '2020-01-01 0:01';

tsl/test/sql/foreign_keys.sql

@@ -650,3 +650,31 @@ 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);
 
+-- test foreign key constraints that have been created before hypertable conversion
+create table converted_pk(time timestamptz, id int, unique(time, id));
+create table converted_fk(time timestamptz, id int, foreign key (time, id) references converted_pk(time, id));
+
+select table_name FROM create_hypertable ('converted_pk', 'time');
+
+\set ON_ERROR_STOP 0
+-- should fail
+INSERT INTO converted_fk SELECT '2020-01-01', 1;
+\set ON_ERROR_STOP 1
+
+INSERT INTO converted_pk SELECT '2020-01-01 0:01', 1;
+
+\set ON_ERROR_STOP 0
+-- should still fail
+INSERT INTO converted_fk SELECT '2020-01-01', 1;
+\set ON_ERROR_STOP 1
+INSERT INTO converted_fk SELECT '2020-01-01 0:01', 1;
+
+\set ON_ERROR_STOP 0
+-- should fail
+DELETE FROM converted_pk WHERE time = '2020-01-01 0:01';
+TRUNCATE converted_pk;
+\set ON_ERROR_STOP 1
+
+DELETE FROM converted_fk;
+DELETE FROM converted_pk WHERE time = '2020-01-01 0:01';
+