Add hint when hypertable creation fails

When creating a hypertable, we create default indexes on the partition
column, which requires that the column be a part of the table's primary
or composite key. The error message shown to the user in this scenario
did not indicate this correctly. This adds a hint to make this clearer.

Closes #2907.

.unreleased/pr_7565

@@ -0,0 +1,2 @@
+Implements: #7565 Add hint when hypertable creation fails
+Thanks: @k-rus for suggesting the improvement

src/indexing.c

@@ -96,7 +96,10 @@ ts_indexing_verify_columns(const Hyperspace *hs, const List *indexelems)
 					(errcode(ERRCODE_TS_BAD_HYPERTABLE_INDEX_DEFINITION),
 					 errmsg("cannot create a unique index without the column \"%s\" (used in "
 							"partitioning)",
-							NameStr(dim->fd.column_name))));
+							NameStr(dim->fd.column_name)),
+					 errhint(
+						 "If you're creating a hypertable on a table with a primary key, ensure "
+						 "the partitioning column is part of the primary or composite key.")));
 	}
 }
 

test/expected/create_hypertable.out

@@ -1121,3 +1121,19 @@ SELECT * FROM show_chunks('test') ch, LATERAL test.show_indexes(ch) ORDER BY 1,
  _timescaledb_internal._hyper_25_24_chunk | _timescaledb_internal._hyper_25_24_chunk_test_val_idx | {val}   |      | f      | f       | f         | 
 (1 row)
 
+-- test creating a hypertable with a primary key where the partitioning column is not part of the primary key
+CREATE TABLE test_schema.partition_not_pk (id INT NOT NULL, device_id INT NOT NULL, time TIMESTAMPTZ NOT NULL, a TEXT NOT NULL, PRIMARY KEY (id));
+\set ON_ERROR_STOP 0
+select create_hypertable ('test_schema.partition_not_pk', 'time');
+ERROR:  cannot create a unique index without the column "time" (used in partitioning)
+HINT:  If you're creating a hypertable on a table with a primary key, ensure the partitioning column is part of the primary or composite key.
+\set ON_ERROR_STOP 1
+DROP TABLE test_schema.partition_not_pk;
+-- test creating a hypertable with a composite key where the partitioning column is not part of the composite key
+CREATE TABLE test_schema.partition_not_pk (id INT NOT NULL, device_id INT NOT NULL, time TIMESTAMPTZ NOT NULL, a TEXT NOT NULL, PRIMARY KEY (id, device_id));
+\set ON_ERROR_STOP 0
+select create_hypertable ('test_schema.partition_not_pk', 'time');
+ERROR:  cannot create a unique index without the column "time" (used in partitioning)
+HINT:  If you're creating a hypertable on a table with a primary key, ensure the partitioning column is part of the primary or composite key.
+\set ON_ERROR_STOP 1
+DROP TABLE test_schema.partition_not_pk;

test/sql/create_hypertable.sql

@@ -666,3 +666,17 @@ SELECT FROM create_hypertable('test', 'time', create_default_indexes => FALSE, m
 -- only user indexes should be returned
 SELECT * FROM test.show_indexes('test') ORDER BY 1;
 SELECT * FROM show_chunks('test') ch, LATERAL test.show_indexes(ch) ORDER BY 1, 2;
+
+-- test creating a hypertable with a primary key where the partitioning column is not part of the primary key
+CREATE TABLE test_schema.partition_not_pk (id INT NOT NULL, device_id INT NOT NULL, time TIMESTAMPTZ NOT NULL, a TEXT NOT NULL, PRIMARY KEY (id));
+\set ON_ERROR_STOP 0
+select create_hypertable ('test_schema.partition_not_pk', 'time');
+\set ON_ERROR_STOP 1
+DROP TABLE test_schema.partition_not_pk;
+
+-- test creating a hypertable with a composite key where the partitioning column is not part of the composite key
+CREATE TABLE test_schema.partition_not_pk (id INT NOT NULL, device_id INT NOT NULL, time TIMESTAMPTZ NOT NULL, a TEXT NOT NULL, PRIMARY KEY (id, device_id));
+\set ON_ERROR_STOP 0
+select create_hypertable ('test_schema.partition_not_pk', 'time');
+\set ON_ERROR_STOP 1
+DROP TABLE test_schema.partition_not_pk;