Add a GUC variable to enable/disable OSM for

SELECTs

src/chunk_scan.c

@@ -11,6 +11,7 @@
 
 #include "debug_point.h"
 #include "dimension_vector.h"
+#include "guc.h"
 #include "hypertable.h"
 #include "hypercube.h"
 #include "scan_iterator.h"

src/guc.c

@@ -73,6 +73,7 @@ bool ts_guc_enable_constraint_exclusion = true;
 bool ts_guc_enable_qual_propagation = true;
 bool ts_guc_enable_cagg_reorder_groupby = true;
 bool ts_guc_enable_now_constify = true;
+bool ts_guc_enable_osm_reads = true;
 TSDLLEXPORT bool ts_guc_enable_transparent_decompression = true;
 bool ts_guc_enable_per_data_node_queries = true;
 bool ts_guc_enable_async_append = true;
@@ -292,6 +293,18 @@ _guc_init(void)
 							 NULL,
 							 NULL);
 
+	DefineCustomBoolVariable("timescaledb.enable_tiered_reads",
+							 "Enable tiered data reads",
+							 "Enable reading of tiered data by including a foreign table "
+							 "representing the data in the object storage into the query plan",
+							 &ts_guc_enable_osm_reads,
+							 true,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+
 	DefineCustomIntVariable("timescaledb.max_insert_batch_size",
 							"The max number of tuples to batch before sending to a data node",
 							"When acting as a access node, TimescaleDB splits batches of "

src/guc.h

@@ -25,6 +25,7 @@ extern bool ts_guc_enable_runtime_exclusion;
 extern bool ts_guc_enable_constraint_exclusion;
 extern bool ts_guc_enable_cagg_reorder_groupby;
 extern bool ts_guc_enable_now_constify;
+extern bool ts_guc_enable_osm_reads;
 extern TSDLLEXPORT bool ts_guc_enable_transparent_decompression;
 extern TSDLLEXPORT bool ts_guc_enable_per_data_node_queries;
 extern TSDLLEXPORT bool ts_guc_enable_async_append;

src/hypertable_restrict_info.c

@@ -20,6 +20,7 @@
 #include "dimension.h"
 #include "dimension_slice.h"
 #include "dimension_vector.h"
+#include "guc.h"
 #include "hypercube.h"
 #include "partitioning.h"
 #include "scan_iterator.h"
@@ -664,6 +665,18 @@ ts_hypertable_restrict_info_get_chunks(HypertableRestrictInfo *hri, Hypertable *
 		 * No restrictions on hyperspace. Just enumerate all the chunks.
 		 */
 		chunk_ids = ts_chunk_get_chunk_ids_by_hypertable_id(ht->fd.id);
+
+		/*
+		 * If the hypertable has an OSM chunk it would end up in the list
+		 * as well. We need to remove it when OSM reads are disabled via GUC
+		 * variable.
+		 */
+		if (!ts_guc_enable_osm_reads)
+		{
+			int32 osm_chunk_id = ts_chunk_get_osm_chunk_id(ht->fd.id);
+
+			chunk_ids = list_delete_int(chunk_ids, osm_chunk_id);
+		}
 	}
 	else
 	{
@@ -686,16 +699,25 @@ ts_hypertable_restrict_info_get_chunks(HypertableRestrictInfo *hri, Hypertable *
 		}
 
 		/*
-		 * Always include the OSM chunk if we have one. It has some virtual
-		 * dimension slices (at the moment, (+inf, +inf) slice for time, but it
-		 * used to be different and might change again.) So sometimes it will
-		 * match and sometimes it won't, so we have to check if it's already
-		 * there not to add a duplicate.
+		 * Always include the OSM chunk if we have one and OSM reads are
+		 * enabled. It has some virtual dimension slices (at the moment,
+		 * (+inf, +inf) slice for time, but it used to be different and might
+		 * change again.) So sometimes it will match and sometimes it won't,
+		 * so we have to check if it's already there not to add a duplicate.
+		 * Similarly if OSM reads are disabled then we exclude the OSM chunk.
 		 */
 		int32 osm_chunk_id = ts_chunk_get_osm_chunk_id(ht->fd.id);
-		if (osm_chunk_id != 0 && !list_member_int(chunk_ids, osm_chunk_id))
+
+		if (osm_chunk_id != INVALID_CHUNK_ID)
 		{
-			chunk_ids = lappend_int(chunk_ids, osm_chunk_id);
+			if (!ts_guc_enable_osm_reads)
+			{
+				chunk_ids = list_delete_int(chunk_ids, osm_chunk_id);
+			}
+			else if (!list_member_int(chunk_ids, osm_chunk_id))
+			{
+				chunk_ids = lappend_int(chunk_ids, osm_chunk_id);
+			}
 		}
 	}
 

tsl/test/expected/chunk_utils_internal.out

@@ -569,6 +569,55 @@ SELECT * from ht_try WHERE timec > '2020-01-01 01:00' ORDER BY 1;
  Thu May 05 01:00:00 2022 PDT |    222 |   222
 (1 row)
 
+--TEST GUC variable to enable/disable OSM chunk
+SET timescaledb.enable_tiered_reads=false;
+EXPLAIN (COSTS OFF) SELECT * from ht_try;
+          QUERY PLAN           
+-------------------------------
+ Seq Scan on _hyper_5_10_chunk
+(1 row)
+
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec > '2022-01-01 01:00';
+                                    QUERY PLAN                                    
+----------------------------------------------------------------------------------
+ Index Scan using _hyper_5_10_chunk_ht_try_timec_idx on _hyper_5_10_chunk
+   Index Cond: (timec > 'Sat Jan 01 01:00:00 2022 PST'::timestamp with time zone)
+(2 rows)
+
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec < '2023-01-01 01:00';
+                                    QUERY PLAN                                    
+----------------------------------------------------------------------------------
+ Index Scan using _hyper_5_10_chunk_ht_try_timec_idx on _hyper_5_10_chunk
+   Index Cond: (timec < 'Sun Jan 01 01:00:00 2023 PST'::timestamp with time zone)
+(2 rows)
+
+SET timescaledb.enable_tiered_reads=true;
+EXPLAIN (COSTS OFF) SELECT * from ht_try;
+              QUERY PLAN               
+---------------------------------------
+ Append
+   ->  Foreign Scan on child_fdw_table
+   ->  Seq Scan on _hyper_5_10_chunk
+(3 rows)
+
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec > '2022-01-01 01:00';
+                                       QUERY PLAN                                       
+----------------------------------------------------------------------------------------
+ Append
+   ->  Foreign Scan on child_fdw_table
+   ->  Index Scan using _hyper_5_10_chunk_ht_try_timec_idx on _hyper_5_10_chunk
+         Index Cond: (timec > 'Sat Jan 01 01:00:00 2022 PST'::timestamp with time zone)
+(4 rows)
+
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec < '2023-01-01 01:00';
+                                       QUERY PLAN                                       
+----------------------------------------------------------------------------------------
+ Append
+   ->  Foreign Scan on child_fdw_table
+   ->  Index Scan using _hyper_5_10_chunk_ht_try_timec_idx on _hyper_5_10_chunk
+         Index Cond: (timec < 'Sun Jan 01 01:00:00 2023 PST'::timestamp with time zone)
+(4 rows)
+
 --TEST insert into a OSM chunk fails. actually any insert will fail. But we just need
 -- to mock the hook and make sure the timescaledb code works correctly.
 SELECT ts_setup_osm_hook();

tsl/test/sql/chunk_utils_internal.sql

@@ -344,6 +344,16 @@ SELECT * from ht_try WHERE  timec > '2000-01-01 01:00' and timec < '2022-01-01 0
 
 SELECT * from ht_try WHERE timec > '2020-01-01 01:00' ORDER BY 1;
 
+--TEST GUC variable to enable/disable OSM chunk
+SET timescaledb.enable_tiered_reads=false;
+EXPLAIN (COSTS OFF) SELECT * from ht_try;
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec > '2022-01-01 01:00';
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec < '2023-01-01 01:00';
+SET timescaledb.enable_tiered_reads=true;
+EXPLAIN (COSTS OFF) SELECT * from ht_try;
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec > '2022-01-01 01:00';
+EXPLAIN (COSTS OFF) SELECT * from ht_try WHERE timec < '2023-01-01 01:00';
+
 --TEST insert into a OSM chunk fails. actually any insert will fail. But we just need
 -- to mock the hook and make sure the timescaledb code works correctly.