\o /dev/null
\ir include/create_single_db.sql
SET client_min_messages = WARNING;
DROP DATABASE IF EXISTS single;
SET client_min_messages = NOTICE;
CREATE DATABASE single;
\c single
CREATE EXTENSION IF NOT EXISTS timescaledb CASCADE;
psql:include/create_single_db.sql:7: NOTICE:  installing required extension "postgres_fdw"
SELECT setup_timescaledb(hostname => 'fakehost'); -- fakehost makes sure there is no network connection
\o
\ir include/sql_query_results.sql
CREATE TABLE PUBLIC.hyper_1 (
  time TIMESTAMP NOT NULL,
  series_0 DOUBLE PRECISION NULL,
  series_1 DOUBLE PRECISION NULL,
  series_2 DOUBLE PRECISION NULL
);
CREATE INDEX "time_plain" ON PUBLIC.hyper_1 (time DESC, series_0);
SELECT * FROM create_hypertable('"public"."hyper_1"'::regclass, 'time'::name, number_partitions => 1, chunk_size_bytes=>10000);
 create_hypertable 
-------------------
 
(1 row)

INSERT INTO hyper_1 SELECT to_timestamp(ser), ser, ser+10000, sqrt(ser::numeric) FROM generate_series(0,10000) ser;
INSERT INTO hyper_1 SELECT to_timestamp(ser), ser, ser+10000, sqrt(ser::numeric) FROM generate_series(10001,20000) ser;
--non-aggregates use MergeAppend in both optimized and non-optimized
EXPLAIN (costs off) SELECT * FROM hyper_1 ORDER BY "time" DESC limit 2;
                             QUERY PLAN                             
--------------------------------------------------------------------
 Limit
   ->  Merge Append
         Sort Key: _hyper_1_0_replica."time" DESC
         ->  Sort
               Sort Key: _hyper_1_0_replica."time" DESC
               ->  Seq Scan on _hyper_1_0_replica
         ->  Sort
               Sort Key: _hyper_1_1_0_partition."time" DESC
               ->  Seq Scan on _hyper_1_1_0_partition
         ->  Index Scan using "1-time_plain" on _hyper_1_1_0_1_data
         ->  Index Scan using "2-time_plain" on _hyper_1_1_0_2_data
(11 rows)

SELECT * FROM hyper_1 ORDER BY "time" DESC limit 2;
           time           | series_0 | series_1 |     series_2     
--------------------------+----------+----------+------------------
 Wed Dec 31 21:33:20 1969 |    20000 |    30000 |  141.42135623731
 Wed Dec 31 21:33:19 1969 |    19999 |    29999 | 141.417820659208
(2 rows)

--aggregates use MergeAppend only in optimized
EXPLAIN (costs off) SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
                                              QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
 Limit
   ->  GroupAggregate
         Group Key: (date_trunc('minute'::text, _hyper_1_0_replica."time"))
         ->  Result
               ->  Merge Append
                     Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                           ->  Seq Scan on _hyper_1_0_replica
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_1_0_partition."time")) DESC
                           ->  Seq Scan on _hyper_1_1_0_partition
                     ->  Index Scan using "1-time_plain" on _hyper_1_1_0_1_data
                     ->  Index Scan using "2-time_plain" on _hyper_1_1_0_2_data
(14 rows)

--the minute and second results should be diff
SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
            t             |   avg   |  min  |       avg        
--------------------------+---------+-------+------------------
 Wed Dec 31 21:33:00 1969 |   19990 | 29980 | 141.385994856058
 Wed Dec 31 21:32:00 1969 | 19949.5 | 29920 | 141.242685621416
(2 rows)

SELECT date_trunc('second', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
            t             |  avg  |  min  |       avg        
--------------------------+-------+-------+------------------
 Wed Dec 31 21:33:20 1969 | 20000 | 30000 |  141.42135623731
 Wed Dec 31 21:33:19 1969 | 19999 | 29999 | 141.417820659208
(2 rows)

--test that when index on time used by constraint, still works correctly
EXPLAIN (costs off)
SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) 
FROM hyper_1 
WHERE time < to_timestamp(900) 
GROUP BY t 
ORDER BY t DESC 
LIMIT 2;
                                                 QUERY PLAN                                                  
-------------------------------------------------------------------------------------------------------------
 Limit
   ->  GroupAggregate
         Group Key: (date_trunc('minute'::text, _hyper_1_0_replica."time"))
         ->  Result
               ->  Merge Append
                     Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                           ->  Seq Scan on _hyper_1_0_replica
                                 Filter: ("time" < 'Wed Dec 31 16:15:00 1969 PST'::timestamp with time zone)
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_1_0_partition."time")) DESC
                           ->  Seq Scan on _hyper_1_1_0_partition
                                 Filter: ("time" < 'Wed Dec 31 16:15:00 1969 PST'::timestamp with time zone)
                     ->  Index Scan using "1-time_plain" on _hyper_1_1_0_1_data
                           Index Cond: ("time" < 'Wed Dec 31 16:15:00 1969 PST'::timestamp with time zone)
                     ->  Index Scan using "2-time_plain" on _hyper_1_1_0_2_data
                           Index Cond: ("time" < 'Wed Dec 31 16:15:00 1969 PST'::timestamp with time zone)
(18 rows)

SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) 
FROM hyper_1 
WHERE time < to_timestamp(900) 
GROUP BY t 
ORDER BY t DESC 
LIMIT 2;
            t             |  avg  |  min  |       avg        
--------------------------+-------+-------+------------------
 Wed Dec 31 16:14:00 1969 | 869.5 | 10840 | 29.4858228711055
 Wed Dec 31 16:13:00 1969 | 809.5 | 10780 | 28.4500853206775
(2 rows)

--test that still works with an expression index on data_trunc.
DROP INDEX "time_plain";
CREATE INDEX "time_trunc" ON PUBLIC.hyper_1 (date_trunc('minute', time));
EXPLAIN (costs off) SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
                                              QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
 Limit
   ->  GroupAggregate
         Group Key: (date_trunc('minute'::text, _hyper_1_0_replica."time"))
         ->  Result
               ->  Merge Append
                     Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                           ->  Seq Scan on _hyper_1_0_replica
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_1_0_partition."time")) DESC
                           ->  Seq Scan on _hyper_1_1_0_partition
                     ->  Index Scan Backward using "3-time_trunc" on _hyper_1_1_0_1_data
                     ->  Index Scan Backward using "4-time_trunc" on _hyper_1_1_0_2_data
(14 rows)

SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
            t             |   avg   |  min  |       avg        
--------------------------+---------+-------+------------------
 Wed Dec 31 21:33:00 1969 |   19990 | 29980 | 141.385994856058
 Wed Dec 31 21:32:00 1969 | 19949.5 | 29920 | 141.242685621416
(2 rows)

--test that works with both indexes
CREATE INDEX "time_plain" ON PUBLIC.hyper_1 (time DESC, series_0);
EXPLAIN (costs off) SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
                                              QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
 Limit
   ->  GroupAggregate
         Group Key: (date_trunc('minute'::text, _hyper_1_0_replica."time"))
         ->  Result
               ->  Merge Append
                     Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_0_replica."time")) DESC
                           ->  Seq Scan on _hyper_1_0_replica
                     ->  Sort
                           Sort Key: (date_trunc('minute'::text, _hyper_1_1_0_partition."time")) DESC
                           ->  Seq Scan on _hyper_1_1_0_partition
                     ->  Index Scan Backward using "3-time_trunc" on _hyper_1_1_0_1_data
                     ->  Index Scan Backward using "4-time_trunc" on _hyper_1_1_0_2_data
(14 rows)

SELECT date_trunc('minute', time) t, avg(series_0), min(series_1), avg(series_2) FROM hyper_1 GROUP BY t ORDER BY t DESC limit 2;
            t             |   avg   |  min  |       avg        
--------------------------+---------+-------+------------------
 Wed Dec 31 21:33:00 1969 |   19990 | 29980 | 141.385994856058
 Wed Dec 31 21:32:00 1969 | 19949.5 | 29920 | 141.242685621416
(2 rows)