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Improve left/inner join performance by rerange right table by keys #60341

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merged 11 commits into from
Sep 11, 2024

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KevinyhZou
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@KevinyhZou KevinyhZou commented Feb 23, 2024

Changelog category (leave one):

  • Performance Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Improve the join performance by rerange the right table by keys while the table keys are dense in left or inner hash join.

Documentation entry for user-facing changes

  • Documentation is written (mandatory for new features)

Information about CI checks: https://clickhouse.com/docs/en/development/continuous-integration/

@KevinyhZou KevinyhZou marked this pull request as draft February 23, 2024 03:21
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Note about that we may have sparse columns and working with them through IColumn interface is critical.

@nikitamikhaylov nikitamikhaylov added the can be tested Allows running workflows for external contributors label Feb 23, 2024
@robot-clickhouse-ci-2 robot-clickhouse-ci-2 added the pr-performance Pull request with some performance improvements label Feb 23, 2024
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robot-clickhouse-ci-2 commented Feb 23, 2024

This is an automated comment for commit 597181c with description of existing statuses. It's updated for the latest CI running

❌ Click here to open a full report in a separate page

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@KevinyhZou KevinyhZou marked this pull request as ready for review February 26, 2024 12:42
@jkartseva jkartseva self-assigned this Feb 28, 2024
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Some initial comments.

{
auto * batch = pool.alloc<Batch>();
*batch = Batch(this);
batch->insert(std::move(row_ref), pool);
return batch;
}

row_nums[size] = row_ref.row_num;
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why row_nums is required? Isn't row_nums[i] essentially the same as row_refs[i].row_num ?

@@ -46,6 +46,7 @@ struct RowRefList : RowRef
SizeT size = 0; /// It's smaller than size_t but keeps align in Arena.
Batch * next;
RowRef row_refs[MAX_SIZE];
UInt64 row_nums[MAX_SIZE];
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The type should be ColumnIndex

Comment on lines 110 to 132
void ColumnString::insertIndicesFrom(const IColumn & src, const IColumn::ColumnIndex * selector, const size_t & size)
{
for (size_t i = 0; i < size; ++i)
insertFrom(src, *(selector + i));
}
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This overload is not different from the base class method.


void nextBatch()
{
batch = batch->next;
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@jkartseva jkartseva Mar 2, 2024

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This invalidates the existing position, using operator ++ and nextBatch() together is not viable.

@@ -55,14 +56,14 @@ struct RowRefList : RowRef

Batch * insert(RowRef && row_ref, Arena & pool)
{
if (full())
if (full() || (size > 0 && row_ref.block != row_refs[0].block))
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The new condition should be in the form a function with a human-readable name.

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KevinyhZou commented Mar 2, 2024

we have optimize inner join use batch insert base on the pr #58278, and on our gluten case , it can performance better. please review it , thanks . @jkartseva

@KevinyhZou KevinyhZou marked this pull request as draft March 4, 2024 01:50
baibaichen pushed a commit to baibaichen/ClickHouse that referenced this pull request Mar 4, 2024
…rom` call

(cherry picked from commit 78303fb993c95765f86a5c65222a0982a38a0e3e)
@KevinyhZou KevinyhZou marked this pull request as ready for review March 14, 2024 01:59
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cc @jkartseva

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Is the most recent iteration ready for review @KevinyhZou ?

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KevinyhZou commented Mar 15, 2024

Is the most recent iteration ready for review @KevinyhZou ?

yes @jkartseva

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vdimir commented Mar 15, 2024

I assume some CI failures can be related, for example

Stateful tests (tsan) — Tests are not finished, fail: 1, passed: 7, skipped: 1 Details

Contains thread sanitizer report around HashJoin::joinBlock, see ThreadSanitizer: data race in stderr.log file:
https://s3.amazonaws.com/clickhouse-test-reports/60341/f266807e0cc64ad8ddcff741594bcc85508bd6ab/stateful_tests__tsan_/stderr.log

Cloud you please check it?

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OK

@KevinyhZou KevinyhZou force-pushed the improve_join_insert_from branch 3 times, most recently from a85bf39 to 9976aeb Compare March 27, 2024 11:21
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cc @vdimir

@KevinyhZou KevinyhZou changed the title Improve inner join performance by decrease insertFrom call Improve left/inner join performance by decrease insertFrom call Apr 2, 2024
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woolenwolfbot bot commented Jun 25, 2024

Dear @jkartseva, this PR hasn't been updated for a while. You will be unassigned. Will you continue working on it? If so, please feel free to reassign yourself.

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any comments about this pr ? @jkartseva

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I'll take a look by the end of the week @KevinyhZou

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I think we should make this feature experimental. I can help with rolling it out to the staging tier in our cloud. If there are no regressions, we may deprecate the experimental flag.

{
for (size_t i = 0; i < block.columns(); ++i)
{
auto & col = *(block.getByPosition(i).column->assumeMutable());
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assumeMutableRef()

Comment on lines 925 to 926
M(Int32, join_to_sort_perkey_rows_threshold, 40, "The lower limit of per-key average rows in the right table to determine whether to sort it in hash join.", 0) \
M(Int32, join_to_sort_table_rows_threshold, 10000, "The upper limit of rows in the right table to determine whether to sort it in hash join.", 0) \
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How were the 40 and 10000 thresholds selected?

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Let's make this feature experimental (e.g., allow_experimental_inner_join_right_table_sorting) and provide a functional test with this setting SET to 1.

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The meaning of the thresholds is unclear without reading the code. We could consider one of the following options: updating the description to clarify how changing the setting affects user-experience (for example, using a special join method that improves performance for wide tables but increases memory consumption) or, even better, removing the thresholds and choosing the best value automatically.

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@KevinyhZou KevinyhZou Sep 4, 2024

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I tested locally and found that if there are many rows on the right but very few matching rows, sorting will lead to performance degradation. In this scenario, I found through testing that 10000 of join_to_sort_table_rows_threshold is a reasonable value, which means the right table is not very big and will not cause significant performance degradation due to sorting. On the contrary, if there are lots of matching rows to output, the threshold can be increased to allow a larger right table to be sorted, which can still achieve significant performance improvement.

And another threshold was set default value 40, as I test on the table when the table is not dense enough, and the sorting may also cause the performance degradation, when the threshold set up to 40, then no performance slow down. @jkartseva

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I have update the description of the threshold settings, take a look at it whether would be ok? @vdimir

@@ -115,6 +115,7 @@ class AddedColumns
}
join_data_avg_perkey_rows = join.getJoinedData()->avgPerKeyRows();
output_by_row_list_threshold = join.getTableJoin().outputByRowListPerkeyRowsThreshold();
join_data_sorted = join.getJoinedData()->sorted;
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Let's move this to the initialization list.


void HashJoin::tryRerangeRightTableData()
{
if ((kind != JoinKind::Inner && kind != JoinKind::Left) || strictness != JoinStrictness::All || table_join->getMixedJoinExpression())
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!isInnerOrLeft(kind)

void HashJoin::tryRerangeRightTableDataImpl(Map & map [[maybe_unused]])
{
constexpr JoinFeatures<KIND, STRICTNESS, Map> join_features;
if constexpr (join_features.is_all_join && (join_features.left || join_features.inner))
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The external function tryRerangeRightTableData already checks these conditions.
Let's throw a LOGICAL_ERROR if they are not satisfied here.

auto it = rows_ref.begin();
if (it.ok())
{
if (blocks.empty() || blocks.back().rows() > DEFAULT_BLOCK_SIZE)
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Shouldn't the condition be blocks.back().rows() >= DEFAULT_BLOCK_SIZE?

kind,
strictness,
data->maps.front(),
false,
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nit: /*prefer_use_maps_all*/ false

src/Interpreters/HashJoin/HashJoin.cpp Outdated Show resolved Hide resolved
Comment on lines 1430 to 1435
if (sample_block_with_columns_to_add.columns() == 0)
{
LOG_DEBUG(log, "The joined right table total rows :{}, total keys :{}, columns added:{}",
data->rows_to_join, data->keys_to_join, sample_block_with_columns_to_add.columns());
return;
}
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Please elaborate on this condition.
Also, why log sample_block_with_columns_to_add.columns()?

data->rows_to_join, data->keys_to_join, sample_block_with_columns_to_add.columns());
return;
}
joinDispatch(
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nit:

[[maybe_unused]] bool result = joinDispatch(...);
chassert(result);

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cc @jkartseva

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I think this looks good, let's adjust the setting names (see comment) and provide cleaner descriptions, and I'll approve & merge.

@@ -922,6 +922,9 @@ class IColumn;
M(Bool, implicit_transaction, false, "If enabled and not already inside a transaction, wraps the query inside a full transaction (begin + commit or rollback)", 0) \
M(UInt64, grace_hash_join_initial_buckets, 1, "Initial number of grace hash join buckets", 0) \
M(UInt64, grace_hash_join_max_buckets, 1024, "Limit on the number of grace hash join buckets", 0) \
M(Int32, join_to_sort_perkey_rows_threshold, 40, "Rerange the right table by key in left or inner hash join when the per-key average rows of it exceed this value (means the table keys is dense) and its number of rows is not too many(controlled by `join_to_sort_table_rows_threshold`), to make the join output by the data batch of key, which would improve performance.", 0) \
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In general, a description should be more focused on the particular setting it's describing.

I think it should be reworded, e.g.:
The lower limit of per-key average rows in the right table to determine whether to rerange the right table by key in left or inner join. This setting ensures that the optimization is not applied for sparse table keys...

Also, the setting name should contain "lower" or "min".

@@ -922,6 +922,9 @@ class IColumn;
M(Bool, implicit_transaction, false, "If enabled and not already inside a transaction, wraps the query inside a full transaction (begin + commit or rollback)", 0) \
M(UInt64, grace_hash_join_initial_buckets, 1, "Initial number of grace hash join buckets", 0) \
M(UInt64, grace_hash_join_max_buckets, 1024, "Limit on the number of grace hash join buckets", 0) \
M(Int32, join_to_sort_perkey_rows_threshold, 40, "Rerange the right table by key in left or inner hash join when the per-key average rows of it exceed this value (means the table keys is dense) and its number of rows is not too many(controlled by `join_to_sort_table_rows_threshold`), to make the join output by the data batch of key, which would improve performance.", 0) \
M(Int32, join_to_sort_table_rows_threshold, 10000, "Rerange the right table by key in left or inner hash join when its number of rows not exceed this value and the table keys is dense (controlled by `join_to_sort_perkey_rows_threshold`), to make the join performance improve as output by the data batch of key, but not cost too much on the table reranging.", 0) \
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Similarly:
The upper threshold of the number of rows in the right table to determine whether to rerange the right table by key in left or inner join.

Or:
The maximum number of rows in the right table...

"upper" or "max" should be in the setting name.

{"input_format_try_infer_datetimes_only_datetime64", true, false, "Allow to infer DateTime instead of DateTime64 in data formats"},
{"join_to_sort_perkey_rows_threshold", 0, 40, "Rerange the right table by key in left or inner hash join when the per-key average rows of it exceed this value (means the table keys is dense) and its number of rows is not too many(controlled by `join_to_sort_table_rows_threshold`), to make the join output by the data batch of key, which would improve performance."},
{"join_to_sort_table_rows_threshold", 0, 10000, "Rerange the right table by key in left or inner hash join when its number of rows not exceed this value and the table keys is dense (controlled by `join_to_sort_perkey_rows_threshold`), to make the join performance improve as output by the data batch of key, but not cost too much on the table reranging."},
{"allow_experimental_join_right_table_sorting", false, false, "If it is set to true, and the conditions of `join_to_sort_perkey_rows_threshold` and `join_to_sort_perkey_rows_threshold` are met, then we will try to rerange the right table by key to improve the performance in left or inner hash join."},
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Let's remove "try" from the description:

"...are met, rerange the right table by key..."

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Looks good, thank you for working on this.

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Please update the Changelog entry with a more generalized summary. The present description is too verbose and focused on the specific case.

@KevinyhZou
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done

@KevinyhZou KevinyhZou changed the title Improve left/inner join performance by decrease insertFrom call Improve left/inner join performance by rerange right table by keys Sep 11, 2024
@jkartseva jkartseva added this pull request to the merge queue Sep 11, 2024
Merged via the queue into ClickHouse:master with commit b5289c1 Sep 11, 2024
215 of 218 checks passed
@robot-clickhouse-ci-1 robot-clickhouse-ci-1 added the pr-synced-to-cloud The PR is synced to the cloud repo label Sep 11, 2024
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zvonand commented Sep 12, 2024

Upgrade check is failing after this one in other PRs:

https://s3.amazonaws.com/clickhouse-test-reports/65488/e76e6d56e17148d34c95cbd91b024dd3b042e4e6/upgrade_check__debug_.html

New settings are not reflected in settings changes history (see new_settings.txt) 	FAIL

   ┌─name────────────────────────────────────────┐
1. │ join_to_sort_minimum_perkey_rows            │
2. │ join_to_sort_maximum_table_rows             │
3. │ allow_experimental_join_right_table_sorting │
   └─────────────────────────────────────────────┘

https://s3.amazonaws.com/clickhouse-test-reports/60341/597181c45e2395991cbb032c7eb2dc3542124e6c/upgrade_check__debug_.html

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It seems this settings should be added to 24.9, and I will try to fix this. @zvonand

@@ -922,6 +922,9 @@ class IColumn;
M(Bool, implicit_transaction, false, "If enabled and not already inside a transaction, wraps the query inside a full transaction (begin + commit or rollback)", 0) \
M(UInt64, grace_hash_join_initial_buckets, 1, "Initial number of grace hash join buckets", 0) \
M(UInt64, grace_hash_join_max_buckets, 1024, "Limit on the number of grace hash join buckets", 0) \
M(Int32, join_to_sort_minimum_perkey_rows, 40, "The lower limit of per-key average rows in the right table to determine whether to rerange the right table by key in left or inner join. This setting ensures that the optimization is not applied for sparse table keys", 0) \
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Same as https://github.com/ClickHouse/ClickHouse/pull/63677/files#r1771844385. Why is this a Int32 it it's treated as unsigned and it shouldn't be negative?

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Yes, the type is wrong. And I have made a pr to change the type to UInt64, #69886

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9 participants