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Fix ordered append for partially compressed chunks
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In the exclusive presence of partially compressed chunks, this
optimization was not applied because no pathkeys were supplied.
Additionally, this patch makes sure that if applicable, the
`enable_decompression_sorted_merge` optimization is chosen for
the path, since it is more beneficial due to the ability to
push down the sort below DecompressChunk.
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@konskov
konskov committed Aug 23, 2023
1 parent d1246ee commit 373c556
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Showing 10 changed files with 4,515 additions and 53 deletions.
51 changes: 24 additions & 27 deletions tsl/src/nodes/decompress_chunk/decompress_chunk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -772,34 +772,31 @@ ts_decompress_chunk_generate_paths(PlannerInfo *root, RelOptInfo *chunk_rel, Hyp
*/
if (batch_merge_path != NULL)
{
Path *merge_append_path =
(Path *) create_merge_append_path_compat(root,
chunk_rel,
list_make2(batch_merge_path,
uncompressed_path),
root->query_pathkeys,
req_outer,
NIL);

add_path(chunk_rel, merge_append_path);
path = (Path *) create_merge_append_path_compat(root,
chunk_rel,
list_make2(batch_merge_path,
uncompressed_path),
root->query_pathkeys,
req_outer,
NIL);
}

/*
* Ideally, we would like for this to be a MergeAppend path.
* However, accumulate_append_subpath will cut out MergeAppend
* and directly add its children, so we have to combine the children
* into a MergeAppend node later, at the chunk append level.
*/
path = (Path *) create_append_path_compat(root,
chunk_rel,
list_make2(path, uncompressed_path),
NIL /* partial paths */,
NIL /* pathkeys */,
req_outer,
0,
false,
false,
path->rows + uncompressed_path->rows);
else
/*
* Ideally, we would like for this to be a MergeAppend path.
* However, accumulate_append_subpath will cut out MergeAppend
* and directly add its children, so we have to combine the children
* into a MergeAppend node later, at the chunk append level.
*/
path = (Path *) create_append_path_compat(root,
chunk_rel,
list_make2(path, uncompressed_path),
NIL /* partial paths */,
root->query_pathkeys /* pathkeys */,
req_outer,
0,
false,
false,
path->rows + uncompressed_path->rows);
}

/* this has to go after the path is copied for the ordered path since path can get freed in
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37 changes: 23 additions & 14 deletions tsl/test/expected/compression.out
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Original file line number Diff line number Diff line change
Expand Up @@ -1972,23 +1972,32 @@ SELECT * FROM ht_metrics_partially_compressed ORDER BY time DESC, device LIMIT 1
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
-> Gather Merge
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
Workers Planned: 2
Output: ht_metrics_partially_compressed."time", ht_metrics_partially_compressed.device, ht_metrics_partially_compressed.value
-> Custom Scan (ChunkAppend) on public.ht_metrics_partially_compressed
Output: ht_metrics_partially_compressed."time", ht_metrics_partially_compressed.device, ht_metrics_partially_compressed.value
Order: ht_metrics_partially_compressed."time" DESC, ht_metrics_partially_compressed.device
Startup Exclusion: false
Runtime Exclusion: false
-> Sort
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
Output: _hyper_41_76_chunk."time", _hyper_41_76_chunk.device, _hyper_41_76_chunk.value
Sort Key: _hyper_41_76_chunk."time" DESC, _hyper_41_76_chunk.device
-> Custom Scan (DecompressChunk) on _timescaledb_internal._hyper_41_76_chunk
Output: _hyper_41_76_chunk."time", _hyper_41_76_chunk.device, _hyper_41_76_chunk.value
-> Seq Scan on _timescaledb_internal.compress_hyper_42_78_chunk
Output: compress_hyper_42_78_chunk."time", compress_hyper_42_78_chunk.device, compress_hyper_42_78_chunk.value, compress_hyper_42_78_chunk._ts_meta_count, compress_hyper_42_78_chunk._ts_meta_sequence_num, compress_hyper_42_78_chunk._ts_meta_min_1, compress_hyper_42_78_chunk._ts_meta_max_1
-> Merge Append
Sort Key: _hyper_41_75_chunk."time" DESC, _hyper_41_75_chunk.device
-> Parallel Append
-> Parallel Seq Scan on _timescaledb_internal._hyper_41_75_chunk
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
-> Custom Scan (DecompressChunk) on _timescaledb_internal._hyper_41_76_chunk
Output: _hyper_41_76_chunk."time", _hyper_41_76_chunk.device, _hyper_41_76_chunk.value
-> Parallel Seq Scan on _timescaledb_internal.compress_hyper_42_78_chunk
Output: compress_hyper_42_78_chunk."time", compress_hyper_42_78_chunk.device, compress_hyper_42_78_chunk.value, compress_hyper_42_78_chunk._ts_meta_count, compress_hyper_42_78_chunk._ts_meta_sequence_num, compress_hyper_42_78_chunk._ts_meta_min_1, compress_hyper_42_78_chunk._ts_meta_max_1
-> Sort
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
Sort Key: _hyper_41_75_chunk."time" DESC, _hyper_41_75_chunk.device
-> Custom Scan (DecompressChunk) on _timescaledb_internal._hyper_41_75_chunk
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
-> Parallel Seq Scan on _timescaledb_internal.compress_hyper_42_77_chunk
-> Seq Scan on _timescaledb_internal.compress_hyper_42_77_chunk
Output: compress_hyper_42_77_chunk."time", compress_hyper_42_77_chunk.device, compress_hyper_42_77_chunk.value, compress_hyper_42_77_chunk._ts_meta_count, compress_hyper_42_77_chunk._ts_meta_sequence_num, compress_hyper_42_77_chunk._ts_meta_min_1, compress_hyper_42_77_chunk._ts_meta_max_1
(19 rows)
-> Sort
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
Sort Key: _hyper_41_75_chunk."time" DESC, _hyper_41_75_chunk.device
-> Seq Scan on _timescaledb_internal._hyper_41_75_chunk
Output: _hyper_41_75_chunk."time", _hyper_41_75_chunk.device, _hyper_41_75_chunk.value
(28 rows)

19 changes: 11 additions & 8 deletions tsl/test/expected/compression_insert.out
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Original file line number Diff line number Diff line change
Expand Up @@ -734,15 +734,15 @@ INSERT INTO trigger_test VALUES
( '2010-01-01',10,10, 'ten', 222);
NOTICE: Trigger t1_mod BEFORE INSERT ROW on _hyper_11_15_chunk: ("Sat Jan 01 00:00:00 2000 PST",1,11,eleven,111) <NULL>
NOTICE: Trigger t1_mod BEFORE INSERT ROW on _hyper_11_18_chunk: ("Fri Jan 01 00:00:00 2010 PST",10,10,ten,222) <NULL>
SELECT * FROM trigger_test ORDER BY 1 ,2, 5;
SELECT * FROM trigger_test ORDER BY 1 ,2, 3, 5;
time | device | value | addcolv | addcoli
------------------------------+--------+-------+---------+---------
Fri Dec 31 22:00:00 1999 PST | 1 | 0 | |
Fri Dec 31 22:00:00 1999 PST | 1 | 0 | |
Sat Jan 01 00:00:00 2000 PST | 1 | 111 | eleven | 111
Sat Jan 01 00:00:00 2000 PST | 1 | 1 | |
Sat Jan 01 00:00:00 2000 PST | 1 | 0 | |
Sat Jan 01 00:00:00 2000 PST | 1 | 0 | |
Sat Jan 01 00:00:00 2000 PST | 1 | 1 | |
Sat Jan 01 00:00:00 2000 PST | 1 | 111 | eleven | 111
Fri Jan 01 00:00:00 2010 PST | 10 | 10 | ten | 222
Fri Jan 01 00:00:00 2010 PST | 10 | 110 | ten | 222
(8 rows)
Expand Down Expand Up @@ -802,15 +802,18 @@ INSERT INTO test_ordering SELECT 1;
:PREFIX SELECT * FROM test_ordering ORDER BY 1;
QUERY PLAN
-------------------------------------------------------------------------------------
Sort
Sort Key: _hyper_13_20_chunk."time"
-> Append
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_sequence_num DESC
-> Seq Scan on compress_hyper_14_21_chunk
-> Seq Scan on _hyper_13_20_chunk
(8 rows)
-> Sort
Sort Key: _hyper_13_20_chunk."time"
-> Seq Scan on _hyper_13_20_chunk
(11 rows)

INSERT INTO test_ordering VALUES (105),(104),(103);
-- should be ordered append
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