Don't analyze the uncompressed chunk before compressing it

We don't use the statistics on the uncompressed chunk anyway. This
significantly improves the compression performance.

tsl/src/compression/compression.c

@@ -150,7 +150,6 @@ static int create_segment_filter_scankey(RowDecompressor *decompressor,
 										 char *segment_filter_col_name, StrategyNumber strategy,
 										 ScanKeyData *scankeys, int num_scankeys,
 										 Bitmapset **null_columns, Datum value, bool isnull);
-static void run_analyze_on_chunk(Oid chunk_relid);
 static void create_per_compressed_column(RowDecompressor *decompressor);
 
 /********************
@@ -425,7 +424,6 @@ compress_chunk(Oid in_table, Oid out_table, int insert_options)
 			row_compressor_process_ordered_slot(&row_compressor, slot, mycid);
 		}
 
-		run_analyze_on_chunk(in_rel->rd_id);
 		if (row_compressor.rows_compressed_into_current_value > 0)
 			row_compressor_flush(&row_compressor, mycid, true);
 
@@ -530,12 +528,6 @@ compress_chunk_sort_relation(CompressionSettings *settings, Relation in_rel)
 
 	table_endscan(scan);
 
-	/* Perform an analyze on the chunk to get up-to-date stats before compressing.
-	 * We do it at this point because we've just read out the entire chunk into
-	 * tuplesort, so its pages are likely to be cached and we can save on I/O.
-	 */
-	run_analyze_on_chunk(in_rel->rd_id);
-
 	ExecDropSingleTupleTableSlot(slot);
 
 	tuplesort_performsort(tuplesortstate);
@@ -591,26 +583,8 @@ compress_chunk_populate_sort_info_for_column(CompressionSettings *settings, Oid
 	ReleaseSysCache(tp);
 }
 
-static void
+/*
-run_analyze_on_chunk(Oid chunk_relid)
+ * Find segment by index for setting the correct sequence number if
-{
-	VacuumRelation vr = {
-		.type = T_VacuumRelation,
-		.relation = NULL,
-		.oid = chunk_relid,
-		.va_cols = NIL,
-	};
-	VacuumStmt vs = {
-		.type = T_VacuumStmt,
-		.rels = list_make1(&vr),
-		.is_vacuumcmd = false,
-		.options = NIL,
-	};
-
-	ExecVacuum(NULL, &vs, true);
-}
-
-/* Find segment by index for setting the correct sequence number if
  * we are trying to roll up chunks while compressing
  */
 static Oid

tsl/test/expected/agg_partials_pushdown.out

@@ -23,6 +23,7 @@ SELECT compress_chunk(c) FROM show_chunks('testtable') c;
  _timescaledb_internal._hyper_1_2_chunk
 (2 rows)
 
+ANALYZE testtable;
 -- Pushdown aggregation to the chunk level
 SELECT count(*), sum(v0), sum(v1), sum(v2), sum(v3) FROM testtable WHERE time >= '2000-01-01 00:00:00+0' AND time <= '2000-02-01 00:00:00+0';
  count | sum | sum | sum | sum 
@@ -61,6 +62,7 @@ SELECT count(*), sum(v0), sum(v1), sum(v2), sum(v3) FROM testtable WHERE time >=
 INSERT INTO testtable(time,device_id,v0,v1,v2,v3)
 SELECT time, device_id, device_id+1,  device_id + 2, device_id + 0.5, NULL
 FROM generate_series('2000-01-01 0:00:00+0'::timestamptz,'2000-01-10 23:55:00+0','1day') gtime(time), generate_series(1,5,1) gdevice(device_id);
+ANALYZE testtable;
 -- Pushdown aggregation to the chunk level
 SELECT count(*), sum(v0), sum(v1), sum(v2), sum(v3) FROM testtable WHERE time >= '2000-01-01 00:00:00+0' AND time <= '2000-02-01 00:00:00+0';
  count | sum | sum | sum | sum 
@@ -177,10 +179,11 @@ SELECT count(*), sum(v0), sum(v1), sum(v2), sum(v3) FROM testtable WHERE time >=
                            Filter: ((compress_hyper_2_4_chunk._ts_meta_max_1 >= ('2000-01-09 00:00:00+0'::cstring)::timestamp with time zone) AND (compress_hyper_2_4_chunk._ts_meta_min_1 <= ('2000-02-01 00:00:00+0'::cstring)::timestamp with time zone))
          ->  Partial Aggregate (actual rows=1 loops=1)
                Output: PARTIAL count(*), PARTIAL sum(_hyper_1_2_chunk.v0), PARTIAL sum(_hyper_1_2_chunk.v1), PARTIAL sum(_hyper_1_2_chunk.v2), PARTIAL sum(_hyper_1_2_chunk.v3)
-               ->  Index Scan using _hyper_1_2_chunk_testtable_time_idx on _timescaledb_internal._hyper_1_2_chunk (actual rows=10 loops=1)
+               ->  Seq Scan on _timescaledb_internal._hyper_1_2_chunk (actual rows=10 loops=1)
                      Output: _hyper_1_2_chunk.v0, _hyper_1_2_chunk.v1, _hyper_1_2_chunk.v2, _hyper_1_2_chunk.v3
-                     Index Cond: ((_hyper_1_2_chunk."time" >= ('2000-01-09 00:00:00+0'::cstring)::timestamp with time zone) AND (_hyper_1_2_chunk."time" <= ('2000-02-01 00:00:00+0'::cstring)::timestamp with time zone))
+                     Filter: ((_hyper_1_2_chunk."time" >= ('2000-01-09 00:00:00+0'::cstring)::timestamp with time zone) AND (_hyper_1_2_chunk."time" <= ('2000-02-01 00:00:00+0'::cstring)::timestamp with time zone))
-(22 rows)
+                     Rows Removed by Filter: 15
+(23 rows)
 
 -- Force plain / sorted aggregation
 SET enable_hashagg = OFF;

tsl/test/expected/compression.out

@@ -1282,12 +1282,6 @@ SELECT relpages, CASE WHEN reltuples > 0 THEN reltuples ELSE 0 END as reltuples
         0 |         0
 (1 row)
 
-SELECT histogram_bounds FROM pg_stats WHERE tablename = :statchunk AND attname = 'c1';
-                                                       histogram_bounds                                                        
--------------------------------------------------------------------------------------------------------------------------------
- {0,250,500,750,1000,1250,1500,1750,2000,2250,2500,2750,3000,3250,3500,3750,4000,4250,4500,4750,5000,5250,5500,5750,6000,6250}
-(1 row)
-
 SELECT compch.table_name  as "STAT_COMP_CHUNK_NAME"
 FROM _timescaledb_catalog.hypertable ht, _timescaledb_catalog.chunk ch
        , _timescaledb_catalog.chunk compch
@@ -1300,15 +1294,8 @@ SELECT relpages, CASE WHEN reltuples > 0 THEN reltuples ELSE 0 END as reltuples
         0 |         0
 (1 row)
 
--- Now verify stats are updated on compressed chunk table when we analyze the hypertable.
-ANALYZE stattest;
-SELECT histogram_bounds FROM pg_stats WHERE tablename = :statchunk AND attname = 'c1';
-                                                       histogram_bounds                                                        
--------------------------------------------------------------------------------------------------------------------------------
- {0,250,500,750,1000,1250,1500,1750,2000,2250,2500,2750,3000,3250,3500,3750,4000,4250,4500,4750,5000,5250,5500,5750,6000,6250}
-(1 row)
-
 -- Unfortunately, the stats on the hypertable won't find any rows to sample from the chunk
+ANALYZE stattest;
 SELECT histogram_bounds FROM pg_stats WHERE tablename = 'stattest' AND attname = 'c1';
  histogram_bounds 
 ------------------

tsl/test/expected/compression_sorted_merge-13.out

@@ -1481,6 +1481,7 @@ SELECT compress_chunk(i) FROM show_chunks('bugtab') i;
  _timescaledb_internal._hyper_11_23_chunk
 (1 row)
 
+ANALYZE bugtab;
 :PREFIX
 SELECT "time","hin"::text,"model"::text,"block"::text,"message_name"::text,"signal_name"::text,"signal_numeric_value","signal_string_value"::text FROM :chunk_table_bugtab ORDER BY "time" DESC;
                                                                                                                                                                                                                                                             QUERY PLAN                                                                                                                                                                                                                                                            

tsl/test/expected/compression_sorted_merge-14.out

@@ -1481,6 +1481,7 @@ SELECT compress_chunk(i) FROM show_chunks('bugtab') i;
  _timescaledb_internal._hyper_11_23_chunk
 (1 row)
 
+ANALYZE bugtab;
 :PREFIX
 SELECT "time","hin"::text,"model"::text,"block"::text,"message_name"::text,"signal_name"::text,"signal_numeric_value","signal_string_value"::text FROM :chunk_table_bugtab ORDER BY "time" DESC;
                                                                                                                                                                                                                                                             QUERY PLAN                                                                                                                                                                                                                                                            

tsl/test/expected/compression_sorted_merge-15.out

@@ -1481,6 +1481,7 @@ SELECT compress_chunk(i) FROM show_chunks('bugtab') i;
  _timescaledb_internal._hyper_11_23_chunk
 (1 row)
 
+ANALYZE bugtab;
 :PREFIX
 SELECT "time","hin"::text,"model"::text,"block"::text,"message_name"::text,"signal_name"::text,"signal_numeric_value","signal_string_value"::text FROM :chunk_table_bugtab ORDER BY "time" DESC;
                                                                                                                                                                                                                                                                QUERY PLAN                                                                                                                                                                                                                                                               

tsl/test/expected/compression_sorted_merge-16.out

@@ -1481,6 +1481,7 @@ SELECT compress_chunk(i) FROM show_chunks('bugtab') i;
  _timescaledb_internal._hyper_11_23_chunk
 (1 row)
 
+ANALYZE bugtab;
 :PREFIX
 SELECT "time","hin"::text,"model"::text,"block"::text,"message_name"::text,"signal_name"::text,"signal_numeric_value","signal_string_value"::text FROM :chunk_table_bugtab ORDER BY "time" DESC;
                                                                                                                                                                                                                                                                QUERY PLAN                                                                                                                                                                                                                                                               

tsl/test/expected/transparent_decompression_join_index-13.out

@@ -1,7 +1,6 @@
 -- 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.
-\c :TEST_DBNAME :ROLE_SUPERUSER
 -- github issue 5585
 create table test (
     time timestamptz not null,
@@ -33,8 +32,11 @@ select compress_chunk(show_chunks('test'));
 
 -- force an index scan
 set enable_seqscan = 'off';
--- disable jit to avoid test flakiness
+-- make some tweaks to avoid flakiness
+analyze test;
+analyze test_copy;
 set jit = off;
+set max_parallel_workers_per_gather = 0;
 explain (costs off) with query_params as (
 	select distinct a, b
 	from test_copy

tsl/test/expected/transparent_decompression_join_index-14.out

@@ -1,7 +1,6 @@
 -- 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.
-\c :TEST_DBNAME :ROLE_SUPERUSER
 -- github issue 5585
 create table test (
     time timestamptz not null,
@@ -33,8 +32,11 @@ select compress_chunk(show_chunks('test'));
 
 -- force an index scan
 set enable_seqscan = 'off';
--- disable jit to avoid test flakiness
+-- make some tweaks to avoid flakiness
+analyze test;
+analyze test_copy;
 set jit = off;
+set max_parallel_workers_per_gather = 0;
 explain (costs off) with query_params as (
 	select distinct a, b
 	from test_copy

tsl/test/expected/transparent_decompression_join_index-15.out

@@ -1,7 +1,6 @@
 -- 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.
-\c :TEST_DBNAME :ROLE_SUPERUSER
 -- github issue 5585
 create table test (
     time timestamptz not null,
@@ -33,8 +32,11 @@ select compress_chunk(show_chunks('test'));
 
 -- force an index scan
 set enable_seqscan = 'off';
--- disable jit to avoid test flakiness
+-- make some tweaks to avoid flakiness
+analyze test;
+analyze test_copy;
 set jit = off;
+set max_parallel_workers_per_gather = 0;
 explain (costs off) with query_params as (
 	select distinct a, b
 	from test_copy

tsl/test/expected/transparent_decompression_join_index-16.out

@@ -1,7 +1,6 @@
 -- 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.
-\c :TEST_DBNAME :ROLE_SUPERUSER
 -- github issue 5585
 create table test (
     time timestamptz not null,
@@ -33,8 +32,11 @@ select compress_chunk(show_chunks('test'));
 
 -- force an index scan
 set enable_seqscan = 'off';
--- disable jit to avoid test flakiness
+-- make some tweaks to avoid flakiness
+analyze test;
+analyze test_copy;
 set jit = off;
+set max_parallel_workers_per_gather = 0;
 explain (costs off) with query_params as (
 	select distinct a, b
 	from test_copy

tsl/test/shared/expected/decompress_tracking.out

@@ -18,6 +18,7 @@ SELECT count(compress_chunk(ch)) FROM show_chunks('decompress_tracking') ch;
      2
 (1 row)
 
+ANALYZE decompress_tracking;
 -- no tracking without analyze
 :EXPLAIN UPDATE decompress_tracking SET value = value + 3;
 QUERY PLAN
@@ -131,31 +132,35 @@ QUERY PLAN
 -- test prepared statements EXPLAIN still works after execution
 SET plan_cache_mode TO force_generic_plan;
 PREPARE p1 AS UPDATE decompress_tracking SET value = value + 3 WHERE device = 'd1';
-BEGIN; EXPLAIN EXECUTE p1; EXECUTE p1; EXPLAIN EXECUTE p1; ROLLBACK;
+BEGIN;
+    EXPLAIN (COSTS OFF) EXECUTE p1;
 QUERY PLAN
- Custom Scan (HypertableModify)  (cost=0.00..70.83 rows=433 width=18)
+ Custom Scan (HypertableModify)
-   ->  Update on decompress_tracking  (cost=0.00..70.83 rows=433 width=18)
+   ->  Update on decompress_tracking
          Update on _hyper_X_X_chunk decompress_tracking_1
          Update on _hyper_X_X_chunk decompress_tracking_2
-         ->  Result  (cost=0.00..70.83 rows=433 width=18)
+         ->  Result
-               ->  Append  (cost=0.00..65.42 rows=433 width=18)
+               ->  Append
-                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1  (cost=0.00..31.62 rows=432 width=18)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1
                            Filter: (device = 'd1'::text)
-                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2  (cost=0.00..31.62 rows=1 width=18)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2
                            Filter: (device = 'd1'::text)
 (10 rows)
 
+    EXECUTE p1;
+    EXPLAIN (COSTS OFF) EXECUTE p1;
 QUERY PLAN
- Custom Scan (HypertableModify)  (cost=0.00..70.83 rows=433 width=18)
+ Custom Scan (HypertableModify)
-   ->  Update on decompress_tracking  (cost=0.00..70.83 rows=433 width=18)
+   ->  Update on decompress_tracking
          Update on _hyper_X_X_chunk decompress_tracking_1
          Update on _hyper_X_X_chunk decompress_tracking_2
-         ->  Result  (cost=0.00..70.83 rows=433 width=18)
+         ->  Result
-               ->  Append  (cost=0.00..65.42 rows=433 width=18)
+               ->  Append
-                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1  (cost=0.00..31.62 rows=432 width=18)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_1
                            Filter: (device = 'd1'::text)
-                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2  (cost=0.00..31.62 rows=1 width=18)
+                     ->  Seq Scan on _hyper_X_X_chunk decompress_tracking_2
                            Filter: (device = 'd1'::text)
 (10 rows)
 
+ROLLBACK;
 DROP TABLE decompress_tracking;

tsl/test/shared/sql/decompress_tracking.sql

@@ -15,6 +15,8 @@ INSERT INTO decompress_tracking SELECT '2020-01-01'::timestamptz + format('%s ho
 
 SELECT count(compress_chunk(ch)) FROM show_chunks('decompress_tracking') ch;
 
+ANALYZE decompress_tracking;
+
 -- no tracking without analyze
 :EXPLAIN UPDATE decompress_tracking SET value = value + 3;
 
@@ -30,6 +32,10 @@ BEGIN; :EXPLAIN_ANALYZE INSERT INTO decompress_tracking (VALUES ('2020-01-01 1:3
 -- test prepared statements EXPLAIN still works after execution
 SET plan_cache_mode TO force_generic_plan;
 PREPARE p1 AS UPDATE decompress_tracking SET value = value + 3 WHERE device = 'd1';
-BEGIN; EXPLAIN EXECUTE p1; EXECUTE p1; EXPLAIN EXECUTE p1; ROLLBACK;
+BEGIN;
+    EXPLAIN (COSTS OFF) EXECUTE p1;
+    EXECUTE p1;
+    EXPLAIN (COSTS OFF) EXECUTE p1;
+ROLLBACK;
 
 DROP TABLE decompress_tracking;

tsl/test/sql/agg_partials_pushdown.sql

@@ -18,6 +18,8 @@ FROM generate_series('2000-01-01 0:00:00+0'::timestamptz,'2000-01-10 23:55:00+0'
 
 SELECT compress_chunk(c) FROM show_chunks('testtable') c;
 
+ANALYZE testtable;
+
 -- Pushdown aggregation to the chunk level
 SELECT count(*), sum(v0), sum(v1), sum(v2), sum(v3) FROM testtable WHERE time >= '2000-01-01 00:00:00+0' AND time <= '2000-02-01 00:00:00+0';
 
@@ -29,6 +31,8 @@ INSERT INTO testtable(time,device_id,v0,v1,v2,v3)
 SELECT time, device_id, device_id+1,  device_id + 2, device_id + 0.5, NULL
 FROM generate_series('2000-01-01 0:00:00+0'::timestamptz,'2000-01-10 23:55:00+0','1day') gtime(time), generate_series(1,5,1) gdevice(device_id);
 
+ANALYZE testtable;
+
 -- Pushdown aggregation to the chunk level
 SELECT count(*), sum(v0), sum(v1), sum(v2), sum(v3) FROM testtable WHERE time >= '2000-01-01 00:00:00+0' AND time <= '2000-02-01 00:00:00+0';
 

tsl/test/sql/compression.sql

@@ -542,7 +542,6 @@ SELECT count(*) from stattest;
 -- Uncompressed chunk table is empty since we just compressed the chunk and moved everything to compressed chunk table.
 -- reltuples is initially -1 on PG14 before VACUUM/ANALYZE was run
 SELECT relpages, CASE WHEN reltuples > 0 THEN reltuples ELSE 0 END as reltuples FROM pg_class WHERE relname = :statchunk;
-SELECT histogram_bounds FROM pg_stats WHERE tablename = :statchunk AND attname = 'c1';
 
 SELECT compch.table_name  as "STAT_COMP_CHUNK_NAME"
 FROM _timescaledb_catalog.hypertable ht, _timescaledb_catalog.chunk ch
@@ -553,10 +552,8 @@ FROM _timescaledb_catalog.hypertable ht, _timescaledb_catalog.chunk ch
 -- reltuples is initially -1 on PG14 before VACUUM/ANALYZE was run
 SELECT relpages, CASE WHEN reltuples > 0 THEN reltuples ELSE 0 END as reltuples FROM pg_class WHERE relname = :'STAT_COMP_CHUNK_NAME';
 
--- Now verify stats are updated on compressed chunk table when we analyze the hypertable.
-ANALYZE stattest;
-SELECT histogram_bounds FROM pg_stats WHERE tablename = :statchunk AND attname = 'c1';
 -- Unfortunately, the stats on the hypertable won't find any rows to sample from the chunk
+ANALYZE stattest;
 SELECT histogram_bounds FROM pg_stats WHERE tablename = 'stattest' AND attname = 'c1';
 SELECT relpages, reltuples FROM pg_class WHERE relname = :statchunk;
 

tsl/test/sql/compression_sorted_merge.sql.in

@@ -524,6 +524,8 @@ SELECT chunk_schema || '.' || chunk_name AS "chunk_table_bugtab"
 
 SELECT compress_chunk(i) FROM show_chunks('bugtab') i;
 
+ANALYZE bugtab;
+
 :PREFIX
 SELECT "time","hin"::text,"model"::text,"block"::text,"message_name"::text,"signal_name"::text,"signal_numeric_value","signal_string_value"::text FROM :chunk_table_bugtab ORDER BY "time" DESC;
 

tsl/test/sql/transparent_decompression_join_index.sql.in

@@ -2,8 +2,6 @@
 -- Please see the included NOTICE for copyright information and
 -- LICENSE-TIMESCALE for a copy of the license.
 
-\c :TEST_DBNAME :ROLE_SUPERUSER
-
 -- github issue 5585
 create table test (
     time timestamptz not null,
@@ -28,8 +26,11 @@ alter table test set (timescaledb.compress, timescaledb.compress_segmentby='a, b
 select compress_chunk(show_chunks('test'));
 -- force an index scan
 set enable_seqscan = 'off';
--- disable jit to avoid test flakiness
+-- make some tweaks to avoid flakiness
+analyze test;
+analyze test_copy;
 set jit = off;
+set max_parallel_workers_per_gather = 0;
 
 explain (costs off) with query_params as (
 	select distinct a, b