Fix handling of chunks with no contraints

When a catalog corruption occurs, and a chunk does not contain any
dimension slices, we crash in ts_dimension_slice_cmp(). This patch adds
a proper check and errors out before the code path is called.

Author: jnidzwetzki

.unreleased/fix_6816

@@ -0,0 +1 @@
+Fixes: #6816 Fix handling of chunks with no contraints

src/chunk_scan.c

@@ -197,6 +197,14 @@ ts_chunk_scan_by_chunk_ids(const Hyperspace *hs, const List *chunk_ids, unsigned
 			Assert(cube->capacity > cube->num_slices);
 			cube->slices[cube->num_slices++] = slice_copy;
 		}
+
+		if (cube->num_slices == 0)
+		{
+			ereport(ERROR,
+					(errcode(ERRCODE_INTERNAL_ERROR),
+					 errmsg("chunk %s has no dimension slices", get_rel_name(chunk->table_id))));
+		}
+
 		ts_hypercube_slice_sort(cube);
 		chunk->cube = cube;
 	}

test/expected/catalog_corruption.out

@@ -0,0 +1,30 @@
+-- This file and its contents are licensed under the Apache License 2.0.
+-- Please see the included NOTICE for copyright information and
+-- LICENSE-APACHE for a copy of the license.
+\c :TEST_DBNAME :ROLE_SUPERUSER
+--- Test handling of missing dimension slices
+CREATE TABLE dim_test(time TIMESTAMPTZ, device int);
+SELECT create_hypertable('dim_test', 'time', chunk_time_interval => INTERVAL '1 day');
+NOTICE:  adding not-null constraint to column "time"
+   create_hypertable   
+-----------------------
+ (1,public,dim_test,t)
+(1 row)
+
+-- Create two chunks
+INSERT INTO dim_test values('2000-01-01 00:00:00', 1);
+INSERT INTO dim_test values('2020-01-01 00:00:00', 1);
+SELECT id AS dim_slice_id FROM _timescaledb_catalog.dimension_slice
+  ORDER BY id DESC LIMIT 1
+  \gset
+-- Delete the dimension slice for the second chunk
+DELETE FROM _timescaledb_catalog.chunk_constraint WHERE dimension_slice_id = :dim_slice_id;
+\set ON_ERROR_STOP 0
+-- Select data
+SELECT * FROM dim_test;
+ERROR:  chunk _hyper_1_2_chunk has no dimension slices
+-- Select data using ordered append
+SELECT * FROM dim_test ORDER BY time;
+ERROR:  chunk _hyper_1_2_chunk has no dimension slices
+\set ON_ERROR_STOP 1
+DROP TABLE dim_test;

test/sql/CMakeLists.txt

@@ -5,6 +5,7 @@ set(TEST_FILES
     alter.sql
     alternate_users.sql
     baserel_cache.sql
+    catalog_corruption.sql
     chunks.sql
     chunk_adaptive.sql
     chunk_utils.sql

test/sql/catalog_corruption.sql

@@ -0,0 +1,33 @@
+-- This file and its contents are licensed under the Apache License 2.0.
+-- Please see the included NOTICE for copyright information and
+-- LICENSE-APACHE for a copy of the license.
+
+\c :TEST_DBNAME :ROLE_SUPERUSER
+
+--- Test handling of missing dimension slices
+CREATE TABLE dim_test(time TIMESTAMPTZ, device int);
+SELECT create_hypertable('dim_test', 'time', chunk_time_interval => INTERVAL '1 day');
+
+-- Create two chunks
+INSERT INTO dim_test values('2000-01-01 00:00:00', 1);
+INSERT INTO dim_test values('2020-01-01 00:00:00', 1);
+
+SELECT id AS dim_slice_id FROM _timescaledb_catalog.dimension_slice
+  ORDER BY id DESC LIMIT 1
+  \gset
+
+-- Delete the dimension slice for the second chunk
+DELETE FROM _timescaledb_catalog.chunk_constraint WHERE dimension_slice_id = :dim_slice_id;
+
+\set ON_ERROR_STOP 0
+
+-- Select data
+SELECT * FROM dim_test;
+
+-- Select data using ordered append
+SELECT * FROM dim_test ORDER BY time;
+
+\set ON_ERROR_STOP 1
+
+DROP TABLE dim_test;
+