Remove sorting from query plan stream properties by KochetovNicolai · Pull Request #68410 · ClickHouse/ClickHouse

KochetovNicolai · 2024-08-15T13:46:06Z

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Because it is too complicated to support.

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robot-clickhouse · 2024-08-15T13:47:37Z

This is an automated comment for commit dfe8eb0 with description of existing statuses. It's updated for the latest CI running

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KochetovNicolai · 2024-08-15T17:38:34Z

tests/queries/0_stateless/02317_distinct_in_order_optimization_explain.reference

-Sorting (Stream): __table1.a ASC, __table1.b ASC
-Sorting (Stream): __table1.a ASC, __table1.b ASC
-Sorting (Stream): a ASC, b ASC
+Sorting: __table1.a ASC


I think this is correct because for a query select distinct b, a from distinct_in_order_explain order by a you don't get (a, b) order after sorting, even if read-in-order with (a, b).

This is because the sorting step does not know anything about b and will use a stable sort (e.g. will prefer the left most input vs input with smallest b) which will break order.

KochetovNicolai · 2024-08-15T17:44:20Z

tests/queries/0_stateless/02377_optimize_sorting_by_input_stream_properties_explain.reference

-Sorting (None)
 Sorting (Sorting for ORDER BY)
-Sorting (Global): plus(a, 1) ASC
-Sorting (Chunk): a ASC


Imho, Chunk sorting does not give any helpful information, so I did remove it:

First of all, I can't guarantee that reading from MergeTree always keeps chunks sorted by PK. Even if so, it is very fragile, e.g. somebody may want to read from different parts in one read task (afiak this is already happening)

So far, Chunk may be used for Sorting (or, maybe, Distinct optimization, but I think that's wrong), but in both cases we do in-order optimization and request Stream sorting.

KochetovNicolai · 2024-08-15T17:47:01Z

tests/queries/0_stateless/02500_remove_redundant_distinct.reference

 Expression (Projection)
  Distinct
    Sorting (Sorting for ORDER BY)
-      Distinct (Preliminary DISTINCT)


The reason of the change is that Preliminary DISTINCT was pushed down over UNION.
I am not sure whether we should remove it in this case, but this was done by remove_redundant_distinct optimization. (why?)

devcrafter

Please see the comments. It's not everything, but can't anymore

devcrafter · 2024-08-21T13:17:26Z

src/Processors/QueryPlan/SortingStep.cpp

-        }
-
-        /// merge sorted
-        if (input_sort_mode == DataStream::SortScope::Stream && input_sort_desc.hasPrefix(result_description))


This case may not be covered with new implementation

devcrafter · 2024-08-28T11:46:10Z

src/Interpreters/InterpreterSelectQuery.cpp

        settings.max_block_size,
        settings.aggregation_in_order_max_block_bytes,
-        std::move(group_by_sort_description),
+        SortDescription{},


We can delete this parameter from MergingAggregatedStep

devcrafter · 2024-08-29T18:48:44Z

src/Processors/QueryPlan/ITransformingStep.cpp


 DataStream ITransformingStep::createOutputStream(
-    const DataStream & input_stream,
+    [[maybe_unused]] const DataStream & input_stream,


Should we delete these parameters at all?

I would like to remove it later, in the next PR.
There are too many steps affected.

Then probably it makes sense to add TODO comment

devcrafter · 2024-08-29T18:50:47Z

src/Interpreters/InterpreterSelectQuery.cpp

    const AggregateDescriptions & aggregates,
    bool should_produce_results_in_order_of_bucket_number,
-    SortDescription group_by_sort_description)
+    [[maybe_unused]] SortDescription group_by_sort_description)


devcrafter · 2024-08-29T19:18:43Z

src/Processors/QueryPlan/Optimizations/optimizeTree.cpp

@@ -199,8 +199,6 @@ void optimizeTreeSecondPass(const QueryPlanOptimizationSettings & optimization_s
            }
        }



Why it was deleted?

It was moved to applyOrder.cpp, the branch for MergingAggregatedStep

devcrafter · 2024-08-29T19:51:31Z

src/Processors/QueryPlan/ReadFromRemote.cpp


-    output_stream.sort_description = std::move(output_sort_description);
-    output_stream.sort_scope = DataStream::SortScope::Stream;
+    // output_stream.sort_description = std::move(output_sort_description);


Remove please

devcrafter · 2024-08-29T19:55:52Z

src/Processors/QueryPlan/ReadFromRemote.cpp

 }

-void ReadFromRemote::enforceSorting(SortDescription output_sort_description)
+void ReadFromRemote::enforceSorting([[maybe_unused]] SortDescription output_sort_description)


Remove param, and rename probably to enableMemoryBoundMerging()

devcrafter · 2024-08-29T19:56:43Z

src/Processors/QueryPlan/ReadFromRemote.cpp

 }

-void ReadFromParallelRemoteReplicasStep::enforceSorting(SortDescription output_sort_description)
+void ReadFromParallelRemoteReplicasStep::enforceSorting([[maybe_unused]] SortDescription output_sort_description)


devcrafter · 2024-08-29T19:58:38Z

src/Processors/QueryPlan/Optimizations/optimizeReadInOrder.cpp

        bool use_buffering = order_info->limit == 0;
        sorting->convertToFinishSorting(order_info->sort_description_for_merging, use_buffering);
-        updateStepsDataStreams(steps_to_update);
+        // updateStepsDataStreams(steps_to_update);


devcrafter · 2024-08-29T19:59:00Z

src/Processors/QueryPlan/Optimizations/optimizeReadInOrder.cpp

+AggregationInputOrder buildInputOrderInfo(AggregatingStep & aggregating, QueryPlan::Node & node)
 {
-    QueryPlan::Node * reading_node = findReadingStep(node, backward_path);
+    QueryPlan::Node * reading_node = findReadingStep(node, false);


comment on parameter

devcrafter · 2024-09-24T09:52:34Z

src/Processors/QueryPlan/DistinctStep.h

        const Names & columns_,
-        bool pre_distinct_, /// If is enabled, execute distinct for separate streams. Otherwise, merge streams.
-        bool optimize_distinct_in_order_);
+        /// If is enabled, execute distinct for separate streams. Otherwise, merge streams.


Probably

Suggested change

/// If is enabled, execute distinct for separate streams. Otherwise, merge streams.

/// If is enabled, execute distinct for separate streams, otherwise for merged streams.

devcrafter · 2024-09-24T10:12:30Z

src/Processors/QueryPlan/ITransformingStep.cpp


 DataStream ITransformingStep::createOutputStream(
-    const DataStream & input_stream,
+    [[maybe_unused]] const DataStream & input_stream,


Then probably it makes sense to add TODO comment

devcrafter · 2024-09-25T08:32:24Z

src/Storages/MergeTree/MergeTask.cpp

            global_ctx->deduplicate_by_columns,
-            false /*pre_distinct*/,
-            true /*optimize_distinct_in_order TODO: looks like it should be enabled*/);
+            false /*pre_distinct*/);


In this case, we do not apply in order optimization anymore - which would lead to increased memory consumption during merges, at least

Oh, that's a good catch!
Looks like we did not have a test for this :(

* [GLUTEN-1632][CH]Daily Update Clickhouse Version (20240928) * Fix build due to ClickHouse/ClickHouse#65625 * Fix build due to ClickHouse/ClickHouse#68410 --------- Co-authored-by: kyligence-git <gluten@kyligence.io> Co-authored-by: Chang Chen <baibaichen@gmail.com>

novikd · 2024-09-30T13:01:36Z

This PR fixed push_down_limit performance test but broke optimize_sorting_for_input_stream.

KochetovNicolai · 2024-09-30T14:07:55Z

Ok, it is only with optimize_read_in_order=0, which is 1 by default.
~~Will fix it later.~~

UPD
I have decided not to fix two failed tests.
They are based on the assumption that reading from MergeTree returns chunks ordered by sorting key

Sorting (Chunk): CounterID ASC, EventDate ASC

I believe this assumption is not valid (or, at least, very fragile). We can easily have a situation when the reading task reads from 2 parts and forms a single chunk from it.
We can enforce returning sorted chunks if needed. But why do we need it if we already have a read-in-order feature enabled by default?

) * [GLUTEN-1632][CH]Daily Update Clickhouse Version (20240928) * Fix build due to ClickHouse/ClickHouse#65625 * Fix build due to ClickHouse/ClickHouse#68410 --------- Co-authored-by: kyligence-git <gluten@kyligence.io> Co-authored-by: Chang Chen <baibaichen@gmail.com>

KochetovNicolai added 5 commits August 7, 2024 17:11

Removing sorting from Plan stream.

9f8113d

Removing sorting from Plan stream.

a379081

Better properties for SortingStep.

9136bc7

Add optimizeDistinctInOrder.

f49fc4c

Update 02317_distinct_in_order_optimization_explain result

a5ada39

robot-ch-test-poll added the pr-not-for-changelog This PR should not be mentioned in the changelog label Aug 15, 2024

KochetovNicolai added 2 commits August 15, 2024 14:04

Fixing style.

41a5e81

Fix some tests.

8cdc04e

KochetovNicolai commented Aug 15, 2024

View reviewed changes

KochetovNicolai added 3 commits August 16, 2024 08:47

Fix some tests.

509bad4

Merge branch 'master' into remove-sorting-from-stream-properties

1d3027b

Cleanup.

abd4d3e

maxknv force-pushed the remove-sorting-from-stream-properties branch from 0f50d2a to a6d53c2 Compare August 16, 2024 11:21

devcrafter self-assigned this Aug 16, 2024

KochetovNicolai force-pushed the remove-sorting-from-stream-properties branch from feb8219 to 1d3027b Compare August 16, 2024 12:06

KochetovNicolai added 6 commits August 16, 2024 12:09

Cleanup

7f1575c

Fixing some tests.

b6af876

Merge branch 'master' into remove-sorting-from-stream-properties

835fb24

Fix tidy

198018b

Unflaky tests.

40db825

Cleanup.

cba404b

KochetovNicolai marked this pull request as ready for review August 19, 2024 08:28

KochetovNicolai and others added 3 commits August 19, 2024 10:56

Merge branch 'master' into remove-sorting-from-stream-properties

5c6bfd9

Merge branch 'master' into remove-sorting-from-stream-properties

9fa9e9e

Update optimizeReadInOrder.cpp

e95843d

devcrafter reviewed Aug 29, 2024

View reviewed changes

Merge branch 'master' into remove-sorting-from-stream-properties

fd73284

KochetovNicolai added 8 commits September 13, 2024 14:39

Fixing build.

243939a

Re-implement optimize_sorting_by_input_stream_properties. Add a test.

5f6d95d

Fixing tests.

83a5ccd

Fixing tests.

5589442

Fixing tests.

a3cd1ba

Refactor optimizeReadInOrder a bit.

80056be

Review fixes.

ca4b366

More review fixes.

d31c9dd

KochetovNicolai requested a review from devcrafter September 18, 2024 09:38

KochetovNicolai added 3 commits September 20, 2024 13:51

Merge branch 'master' into remove-sorting-from-stream-properties

77f7e1b

Update QueryPlanOptimizationSettings.cpp

1f0323c

Merge branch 'master' into remove-sorting-from-stream-properties

9004bb6

devcrafter reviewed Sep 25, 2024

View reviewed changes

KochetovNicolai added 2 commits September 26, 2024 12:36

Merge branch 'master' into remove-sorting-from-stream-properties

e0599ff

Review fixes.

dfe8eb0

KochetovNicolai added this pull request to the merge queue Sep 27, 2024

Merged via the queue into master with commit a8fe70f Sep 27, 2024

KochetovNicolai deleted the remove-sorting-from-stream-properties branch September 27, 2024 10:39

robot-ch-test-poll1 added the pr-synced-to-cloud The PR is synced to the cloud repo label Sep 27, 2024

baibaichen added a commit to Kyligence/gluten that referenced this pull request Sep 28, 2024

Fix build due to ClickHouse/ClickHouse#68410

c317908

This was referenced Sep 30, 2024

Analyzer: Broken performance tests #62245

Closed

Analyzer: fix push down limit #65100

Closed

KochetovNicolai mentioned this pull request Oct 1, 2024

Remove QueryPlan DataStream. #70158

Merged

20 tasks

		@@ -199,8 +199,6 @@ void optimizeTreeSecondPass(const QueryPlanOptimizationSettings & optimization_s
		}
		}

	/// If is enabled, execute distinct for separate streams. Otherwise, merge streams.
	/// If is enabled, execute distinct for separate streams, otherwise for merged streams.

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KochetovNicolai commented Aug 15, 2024 •

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robot-clickhouse commented Aug 15, 2024 •

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