[KYUUBI #6691] A new Spark SQL command to merge small files

[gabrywu]

🔍 Description

Issue References 🔗

This pull request closing #6691

Describe Your Solution 🔧

There are many cases in which a SQL generate small files, we MUST merge them into bigger ones.
I create a new Spark SQL command to merge small files, which doesn't read-write all of the records of a table, it just merges files in a binary level. Take a CSV table for example, it only appends the byte array from one file to another one, without reading & writing records

Syntax here

compact table table_name [INTO ${targetFileSize} ${targetFileSizeUnit} ] [ cleanup | retain | list ]
-- targetFileSizeUnit can be 'm','mb'
-- cleanup means cleaning compact staging folders, which contains original small files, default behavior
-- retain means retaining compact staging folders, for testing, and we can recover with the staging data
-- list means this command only get the merging result, and don't run actually

recover compact table table_name
-- recover a table if compact table command fails

Types of changes 🔖

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Test Plan 🧪

Behavior Without This Pull Request ⚰️

Behavior With This Pull Request 🎉

Related Unit Tests

---

Checklist 📝

• This patch was not authored or co-authored using Generative Tooling

Be nice. Be informative.

[pan3793]

cc @ulysses-you

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 582 lines in your changes missing coverage. Please review.

Project coverage is 0.00%. Comparing base (353877b) to head (fd39f66).
Report is 26 commits behind head on master.

Files with missing lines	Patch %	Lines
...ache/kyuubi/sql/compact/SmallFileCollectExec.scala	0.00%	75 Missing ⚠️
.../kyuubi/sql/compact/merge/AbstractFileMerger.scala	0.00%	61 Missing ⚠️
...yuubi/sql/compact/RecoverCompactTableCommand.scala	0.00%	46 Missing ⚠️
...ache/kyuubi/sql/compact/CompactTableResolver.scala	0.00%	43 Missing ⚠️
...a/org/apache/kyuubi/sql/compact/CompactTable.scala	0.00%	38 Missing ⚠️
...e/kyuubi/sql/compact/merge/ParquetFileMerger.scala	0.00%	36 Missing ⚠️
...apache/kyuubi/sql/compact/SmallFileMergeExec.scala	0.00%	34 Missing ⚠️
...uubi/sql/compact/CachePerformanceViewCommand.scala	0.00%	33 Missing ⚠️
.../apache/kyuubi/sql/compact/CompactTableUtils.scala	0.00%	33 Missing ⚠️
...a/org/apache/spark/sql/SparkInternalExplorer.scala	0.00%	26 Missing ⚠️
... and 12 more

Additional details and impacted files

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  Coverage    0.00%   0.00%            
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  Files         682     706    +24     
  Lines       42192   42861   +669     
  Branches     5755    5851    +96     
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- Misses      42192   42861   +669     

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[gabrywu]

@cxzl25 @ulysses-you all tests pass

[ulysses-you]

thank you @gabrywu , about the syntax, is there any reason to introduce compact table ? Why not use procedure like

Call kyuubi.compact(table => 'xx', targetSizeInBytes => 'xxx', mode => 'xxx')

[gabrywu]

thank you @gabrywu , about the syntax, is there any reason to introduce compact table ? Why not use procedure like

Call kyuubi.compact(table => 'xx', targetSizeInBytes => 'xxx', mode => 'xxx')

The answer is same to the question, why use procedure?
I created this command based on spark2.x when the call procedure was not the mainstream proposal.
And by the way, a call procedure is becoming a mainstream proposal?

[gabrywu]

@cxzl25 what do you think of the call kyuubi.compact procedure?

[gabrywu]

@AngersZhuuuu can you help to review this PR?

[pan3793]

For the syntax part, given Delta and Iceberg's dominance in the lakehouse market, I suggest following either Delta's VACCUM or Iceberg's CALL syntax.

Additional information:

• Kyuubi Spark extension already adopted Delta ZORDER syntax
• Spark 4.0 adopting the Iceberg CALL syntax, see SPARK-48781

[gabrywu]

we'd better talk about the syntax and make a final decision in the dev emails dev@kyuubi.apache.org, otherwise, the upcoming PR will still not use CALL procedure
@pan3793 , @ulysses-you , @cxzl25

[gabrywu]

An email thread to decide which one should be used, command or call procedure
[VOTE][DISCUSS] A Spark SQL command or Call procedure

[turboFei]

do you support to compact one partition for partitioned table？

[gabrywu]

do you support to compact one partition for partitioned table？

hi, @turboFei I removed this feature from this PR. only support partition table internally.

[gabrywu]

Close this PR and will create a new one if apache/spark/pull/47190 is released in next Spark version v4.0.0