Add index creation for chunks without segmentby

Previously, for chunks without a segmentby column specified in the
compression settings, no indexes were created. This change allows
indexes to be created on orderby columns only in this scenario.

Since there is no segmentby in the compression settings for these chunks
we also disable segmentwise recompression for them as it is more optimal
to do a full recompression in this case.

.unreleased/pr_7436

@@ -0,0 +1 @@
+Implements: #7436 Add index creation on orderby columns

tsl/src/compression/api.c

@@ -1051,6 +1051,14 @@ get_compressed_chunk_index_for_recompression(Chunk *uncompressed_chunk)
 
 	CompressionSettings *settings = ts_compression_settings_get(compressed_chunk->table_id);
 
+	int num_segmentby = ts_array_length(settings->fd.segmentby);
+
+	if(num_segmentby == 0) {
+		table_close(compressed_chunk_rel, NoLock);
+		table_close(uncompressed_chunk_rel, NoLock);
+		return InvalidOid;
+	}
+
 	CatalogIndexState indstate = CatalogOpenIndexes(compressed_chunk_rel);
 	Oid index_oid = get_compressed_chunk_index(indstate, settings);
 	CatalogCloseIndexes(indstate);

tsl/src/compression/compression_storage.c

@@ -308,11 +308,6 @@ create_compressed_chunk_indexes(Chunk *chunk, CompressionSettings *settings)
 		}
 	}
 
-	if (list_length(indexcols) == 0)
-	{
-		return;
-	}
-
 	SortByDir ordering;
 	SortByNulls nulls_ordering;
 

tsl/test/expected/compression_bgw.out

@@ -175,8 +175,8 @@ WHERE compression_status LIKE 'Compressed'
 ORDER BY chunk_name;
     chunk_name    | before_compression_total_bytes | after_compression_total_bytes 
 ------------------+--------------------------------+-------------------------------
- _hyper_3_5_chunk |                          24576 |                         24576
- _hyper_3_6_chunk |                          24576 |                         24576
+ _hyper_3_5_chunk |                          24576 |                         40960
+ _hyper_3_6_chunk |                          24576 |                         40960
 (2 rows)
 
 --integer tests
@@ -215,8 +215,8 @@ WHERE compression_status LIKE 'Compressed'
 ORDER BY chunk_name;
     chunk_name     | before_compression_total_bytes | after_compression_total_bytes 
 -------------------+--------------------------------+-------------------------------
- _hyper_5_12_chunk |                          24576 |                         24576
- _hyper_5_13_chunk |                          24576 |                         24576
+ _hyper_5_12_chunk |                          24576 |                         40960
+ _hyper_5_13_chunk |                          24576 |                         40960
 (2 rows)
 
 --bigint test
@@ -255,8 +255,8 @@ WHERE compression_status LIKE 'Compressed'
 ORDER BY chunk_name;
     chunk_name     | before_compression_total_bytes | after_compression_total_bytes 
 -------------------+--------------------------------+-------------------------------
- _hyper_7_19_chunk |                          24576 |                         24576
- _hyper_7_20_chunk |                          24576 |                         24576
+ _hyper_7_19_chunk |                          24576 |                         40960
+ _hyper_7_20_chunk |                          24576 |                         40960
 (2 rows)
 
 --TEST 8

tsl/test/expected/compression_indexcreate.out

@@ -0,0 +1,124 @@
+-- This file and its contents are licensed under the Timescale License.
+-- Please see the included NOTICE for copyright information and
+-- LICENSE-TIMESCALE for a copy of the license.
+-- force index scan to be used when possible
+set enable_seqscan to false;
+\set PREFIX 'EXPLAIN (analyze, costs off, summary off, timing off) '
+create table segind(time timestamptz, a int, b int);
+select create_hypertable('segind', by_range('time'));
+NOTICE:  adding not-null constraint to column "time"
+ create_hypertable 
+-------------------
+ (1,t)
+(1 row)
+
+-- enable compression on hypertable with no segment by column
+alter table segind set (timescaledb.compress, timescaledb.compress_segmentby='', timescaledb.compress_orderby='time, b');
+insert into segind values('2024-11-08 10:31:28.436014-07', 1, 1), ('2024-11-08 10:32:28.436014-07', 2, 1), ('2024-11-08 10:33:28.436014-07', 3, 1), ('2024-11-08 10:34:28.436014-07', 2, 1), ('2024-11-08 10:35:28.436014-07', 1, 2), ('2024-11-08 10:36:28.436014-07', 4, 1);
+-- compress chunk
+-- this should create an index using orderby columns
+select compress_chunk(show_chunks('segind'));
+             compress_chunk             
+----------------------------------------
+ _timescaledb_internal._hyper_1_1_chunk
+(1 row)
+
+-- query using orderby columns should use the index
+:PREFIX select * from segind where b = 1;
+                                                                 QUERY PLAN                                                                 
+--------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=5 loops=1)
+   Vectorized Filter: (b = 1)
+   Rows Removed by Filter: 1
+   ->  Index Scan using compress_hyper_2_2_chunk__ts_meta_min_1__ts_meta_max_1__ts__idx on compress_hyper_2_2_chunk (actual rows=1 loops=1)
+         Index Cond: ((_ts_meta_min_2 <= 1) AND (_ts_meta_max_2 >= 1))
+(5 rows)
+
+:PREFIX select * from segind where time = '2024-11-08 10:32:28.436014-07';
+                                                                                            QUERY PLAN                                                                                             
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=1 loops=1)
+   Vectorized Filter: ("time" = 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone)
+   Rows Removed by Filter: 5
+   ->  Index Scan using compress_hyper_2_2_chunk__ts_meta_min_1__ts_meta_max_1__ts__idx on compress_hyper_2_2_chunk (actual rows=1 loops=1)
+         Index Cond: ((_ts_meta_min_1 <= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone) AND (_ts_meta_max_1 >= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone))
+(5 rows)
+
+:PREFIX select * from segind where b = 1 and time = '2024-11-08 10:32:28.436014-07';
+                                                                                                                      QUERY PLAN                                                                                                                       
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=1 loops=1)
+   Vectorized Filter: ((b = 1) AND ("time" = 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone))
+   Rows Removed by Filter: 5
+   ->  Index Scan using compress_hyper_2_2_chunk__ts_meta_min_1__ts_meta_max_1__ts__idx on compress_hyper_2_2_chunk (actual rows=1 loops=1)
+         Index Cond: ((_ts_meta_min_1 <= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone) AND (_ts_meta_max_1 >= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone) AND (_ts_meta_min_2 <= 1) AND (_ts_meta_max_2 >= 1))
+(5 rows)
+
+-- a query on another column should perform a seq scan since there is no index on it
+:PREFIX select * from segind where a = 1;
+                                QUERY PLAN                                 
+---------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=2 loops=1)
+   Vectorized Filter: (a = 1)
+   Rows Removed by Filter: 4
+   ->  Seq Scan on compress_hyper_2_2_chunk (actual rows=1 loops=1)
+(4 rows)
+
+-- decompress the chunk to drop the index
+select decompress_chunk(show_chunks('segind'));
+            decompress_chunk            
+----------------------------------------
+ _timescaledb_internal._hyper_1_1_chunk
+(1 row)
+
+-- change compression settings to use segmentby column
+alter table segind set (timescaledb.compress, timescaledb.compress_segmentby='a', timescaledb.compress_orderby='time, b');
+-- compress chunk
+-- this should create an index using segmentby and orderby columns
+select compress_chunk(show_chunks('segind'));
+             compress_chunk             
+----------------------------------------
+ _timescaledb_internal._hyper_1_1_chunk
+(1 row)
+
+-- queries using segmentby or orderby columns should use the index
+:PREFIX select * from segind where b = 1;
+                                                                 QUERY PLAN                                                                 
+--------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=5 loops=1)
+   Vectorized Filter: (b = 1)
+   Rows Removed by Filter: 1
+   ->  Index Scan using compress_hyper_2_3_chunk_a__ts_meta_min_1__ts_meta_max_1__t_idx on compress_hyper_2_3_chunk (actual rows=4 loops=1)
+         Index Cond: ((_ts_meta_min_2 <= 1) AND (_ts_meta_max_2 >= 1))
+(5 rows)
+
+:PREFIX select * from segind where time = '2024-11-08 10:32:28.436014-07';
+                                                                                            QUERY PLAN                                                                                             
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=1 loops=1)
+   Vectorized Filter: ("time" = 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone)
+   Rows Removed by Filter: 3
+   ->  Index Scan using compress_hyper_2_3_chunk_a__ts_meta_min_1__ts_meta_max_1__t_idx on compress_hyper_2_3_chunk (actual rows=2 loops=1)
+         Index Cond: ((_ts_meta_min_1 <= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone) AND (_ts_meta_max_1 >= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone))
+(5 rows)
+
+:PREFIX select * from segind where b = 1 and time = '2024-11-08 10:32:28.436014-07';
+                                                                                                                      QUERY PLAN                                                                                                                       
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=1 loops=1)
+   Vectorized Filter: ((b = 1) AND ("time" = 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone))
+   Rows Removed by Filter: 3
+   ->  Index Scan using compress_hyper_2_3_chunk_a__ts_meta_min_1__ts_meta_max_1__t_idx on compress_hyper_2_3_chunk (actual rows=2 loops=1)
+         Index Cond: ((_ts_meta_min_1 <= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone) AND (_ts_meta_max_1 >= 'Fri Nov 08 09:32:28.436014 2024 PST'::timestamp with time zone) AND (_ts_meta_min_2 <= 1) AND (_ts_meta_max_2 >= 1))
+(5 rows)
+
+:PREFIX select * from segind where a = 1;
+                                                                 QUERY PLAN                                                                 
+--------------------------------------------------------------------------------------------------------------------------------------------
+ Custom Scan (DecompressChunk) on _hyper_1_1_chunk (actual rows=2 loops=1)
+   ->  Index Scan using compress_hyper_2_3_chunk_a__ts_meta_min_1__ts_meta_max_1__t_idx on compress_hyper_2_3_chunk (actual rows=1 loops=1)
+         Index Cond: (a = 1)
+(3 rows)
+
+-- cleanup
+RESET enable_seqscan;

tsl/test/expected/compression_insert.out

@@ -790,13 +790,11 @@ SELECT compress_chunk(format('%I.%I',chunk_schema,chunk_name), true) FROM timesc
 
 -- should be ordered append
 :PREFIX SELECT * FROM test_ordering ORDER BY 1;
-                                               QUERY PLAN                                               
---------------------------------------------------------------------------------------------------------
+                                                         QUERY PLAN                                                         
+----------------------------------------------------------------------------------------------------------------------------
  Custom Scan (DecompressChunk) on _hyper_13_20_chunk
-   ->  Sort
-         Sort Key: compress_hyper_14_21_chunk._ts_meta_min_1, compress_hyper_14_21_chunk._ts_meta_max_1
-         ->  Seq Scan on compress_hyper_14_21_chunk
-(4 rows)
+   ->  Index Scan Backward using compress_hyper_14_21_chunk__ts_meta_min_1__ts_meta_max_1_idx on compress_hyper_14_21_chunk
+(2 rows)
 
 INSERT INTO test_ordering SELECT 1;
 -- should not be ordered append
@@ -807,39 +805,35 @@ INSERT INTO test_ordering SELECT 1;
 -- It was hard to include a path without pushed down sort for consideration, as `add_path` would reject
 -- the path with sort pushdown, which is desirable in most cases
 :PREFIX SELECT * FROM test_ordering ORDER BY 1;
-                                                     QUERY PLAN                                                     
---------------------------------------------------------------------------------------------------------------------
+                                                               QUERY PLAN                                                               
+----------------------------------------------------------------------------------------------------------------------------------------
  Custom Scan (ChunkAppend) on test_ordering
    Order: test_ordering."time"
    ->  Merge Append
          Sort Key: _hyper_13_20_chunk."time"
          ->  Custom Scan (DecompressChunk) on _hyper_13_20_chunk
-               ->  Sort
-                     Sort Key: compress_hyper_14_21_chunk._ts_meta_min_1, compress_hyper_14_21_chunk._ts_meta_max_1
-                     ->  Seq Scan on compress_hyper_14_21_chunk
+               ->  Index Scan Backward using compress_hyper_14_21_chunk__ts_meta_min_1__ts_meta_max_1_idx on compress_hyper_14_21_chunk
          ->  Sort
                Sort Key: _hyper_13_20_chunk."time"
                ->  Seq Scan on _hyper_13_20_chunk
-(11 rows)
+(9 rows)
 
 INSERT INTO test_ordering VALUES (105),(104),(103);
 -- should be ordered append
 :PREFIX SELECT * FROM test_ordering ORDER BY 1;
-                                                     QUERY PLAN                                                     
---------------------------------------------------------------------------------------------------------------------
+                                                               QUERY PLAN                                                               
+----------------------------------------------------------------------------------------------------------------------------------------
  Custom Scan (ChunkAppend) on test_ordering
    Order: test_ordering."time"
    ->  Merge Append
          Sort Key: _hyper_13_20_chunk."time"
          ->  Custom Scan (DecompressChunk) on _hyper_13_20_chunk
-               ->  Sort
-                     Sort Key: compress_hyper_14_21_chunk._ts_meta_min_1, compress_hyper_14_21_chunk._ts_meta_max_1
-                     ->  Seq Scan on compress_hyper_14_21_chunk
+               ->  Index Scan Backward using compress_hyper_14_21_chunk__ts_meta_min_1__ts_meta_max_1_idx on compress_hyper_14_21_chunk
          ->  Sort
                Sort Key: _hyper_13_20_chunk."time"
                ->  Seq Scan on _hyper_13_20_chunk
    ->  Index Only Scan Backward using _hyper_13_22_chunk_test_ordering_time_idx on _hyper_13_22_chunk
-(12 rows)
+(10 rows)
 
 --insert into compressed + uncompressed chunk
 INSERT INTO test_ordering VALUES (21), (22),(113);
@@ -881,19 +875,15 @@ SELECT compress_chunk(format('%I.%I',chunk_schema,chunk_name), true) FROM timesc
 
 -- should be ordered append
 :PREFIX SELECT * FROM test_ordering ORDER BY 1;
-                                                  QUERY PLAN                                                  
---------------------------------------------------------------------------------------------------------------
+                                                            QUERY PLAN                                                            
+----------------------------------------------------------------------------------------------------------------------------------
  Custom Scan (ChunkAppend) on test_ordering
    Order: test_ordering."time"
    ->  Custom Scan (DecompressChunk) on _hyper_13_20_chunk
-         ->  Sort
-               Sort Key: compress_hyper_14_23_chunk._ts_meta_min_1, compress_hyper_14_23_chunk._ts_meta_max_1
-               ->  Seq Scan on compress_hyper_14_23_chunk
+         ->  Index Scan Backward using compress_hyper_14_23_chunk__ts_meta_min_1__ts_meta_max_1_idx on compress_hyper_14_23_chunk
    ->  Custom Scan (DecompressChunk) on _hyper_13_22_chunk
-         ->  Sort
-               Sort Key: compress_hyper_14_24_chunk._ts_meta_min_1, compress_hyper_14_24_chunk._ts_meta_max_1
-               ->  Seq Scan on compress_hyper_14_24_chunk
-(10 rows)
+         ->  Index Scan Backward using compress_hyper_14_24_chunk__ts_meta_min_1__ts_meta_max_1_idx on compress_hyper_14_24_chunk
+(6 rows)
 
 SET timescaledb.enable_decompression_sorted_merge = 1;
 -- TEST cagg triggers with insert into compressed chunk

tsl/test/expected/compression_qualpushdown.out

@@ -135,9 +135,9 @@ order by factorid, end_dt;
          Output: _hyper_3_4_chunk.factorid, _hyper_3_4_chunk.end_dt, _hyper_3_4_chunk.logret
          Filter: ((_hyper_3_4_chunk.end_dt >= '12-10-2012'::date) AND (_hyper_3_4_chunk.end_dt <= '12-11-2012'::date))
          Vectorized Filter: (_hyper_3_4_chunk.fmid = 56)
-         ->  Seq Scan on _timescaledb_internal.compress_hyper_4_5_chunk
+         ->  Index Scan using compress_hyper_4_5_chunk__ts_meta_min_1__ts_meta_max_1_idx on _timescaledb_internal.compress_hyper_4_5_chunk
                Output: compress_hyper_4_5_chunk._ts_meta_count, compress_hyper_4_5_chunk.fmid, compress_hyper_4_5_chunk.factorid, compress_hyper_4_5_chunk.start_dt, compress_hyper_4_5_chunk._ts_meta_min_1, compress_hyper_4_5_chunk._ts_meta_max_1, compress_hyper_4_5_chunk.end_dt, compress_hyper_4_5_chunk.interval_number, compress_hyper_4_5_chunk.logret, compress_hyper_4_5_chunk.knowledge_date
-               Filter: ((compress_hyper_4_5_chunk._ts_meta_max_1 >= '12-10-2012'::date) AND (compress_hyper_4_5_chunk._ts_meta_min_1 <= '12-11-2012'::date))
+               Index Cond: ((compress_hyper_4_5_chunk._ts_meta_min_1 <= '12-11-2012'::date) AND (compress_hyper_4_5_chunk._ts_meta_max_1 >= '12-10-2012'::date))
 (10 rows)
 
 --no pushdown here