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ARROW-5902: [Java] Implement hash table and equals & hashCode API for dictionary encoding#4846

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tianchen92 wants to merge 6 commits intoapache:masterfrom
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ARROW-5902: [Java] Implement hash table and equals & hashCode API for dictionary encoding#4846
tianchen92 wants to merge 6 commits intoapache:masterfrom
tianchen92:hasher

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@tianchen92 tianchen92 commented Jul 10, 2019

As discussed in #4792

Implement a hash table to only store hash & index, meanwhile add check equal function in ValueVector API.

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tianchen92 commented Jul 10, 2019

@emkornfield Hi Micah, I made a simple implementation for dictionary hash table.
1 Implement hash table to store dictionary vector hash & index, support lookup with given toEncode vector index.
2 add hashCode and equals methods in ValueVector API.
Please take a look and give some comments, thanks!

liyafan82
liyafan82 reviewed Jul 11, 2019
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tianchen92 commented Jul 11, 2019

@liyafan82 Thanks for your comments, This PR is just a demo as I commented as WIP and this will work for VarCharVector type encoding in TestDictionaryVector to test correctness. default and memory copy already commented as TODO to make it perfect since we have to use memory level hashCode and implement equals in all type vectors.

@tianchen92 tianchen92 mentioned this pull request Jul 12, 2019
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@tianchen92 tianchen92 changed the title ARROW-5902: [Java][WIP] Implement HashTable for dictionary encoding ARROW-5902: [Java] Implement hash table and equals & hashCode API for dictionary encoding Jul 13, 2019
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codecov-io commented Jul 13, 2019 •
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Codecov Report

Merging #4846 into master will increase coverage by 2.16%.
The diff coverage is n/a.

Impacted file tree graph

@@            Coverage Diff             @@
##           master    #4846      +/-   ##
==========================================
+ Coverage   87.42%   89.58%   +2.16%     
==========================================
  Files         994      661     -333     
  Lines      140102    96617   -43485     
  Branches     1418        0    -1418     
==========================================
- Hits       122481    86555   -35926     
+ Misses      17259    10062    -7197     
+ Partials      362        0     -362
Impacted Files Coverage Δ
cpp/src/gandiva/precompiled/decimal_ops.cc 97.17% <0%> (ø) ⬆️
cpp/src/gandiva/precompiled/decimal_ops_test.cc 97.43% <0%> (ø) ⬆️
r/src/recordbatch.cpp
r/R/Table.R
js/src/util/fn.ts
go/arrow/array/bufferbuilder.go
r/src/symbols.cpp
rust/datafusion/src/execution/projection.rs
rust/datafusion/src/execution/filter.rs
rust/arrow/src/csv/writer.rs
... and 326 more

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emkornfield
emkornfield reviewed Jul 16, 2019
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java/vector/src/main/java/org/apache/arrow/vector/util/ByteFunctionHelpers.java Outdated
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this is a no-op I believe.

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@tianchen92 tianchen92 Jul 16, 2019

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Thanks for comments, IMO, what dose this mean? :)

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@emkornfield Could you please explain this a little more? thanks

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@emkornfield emkornfield Jul 18, 2019

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I think Integer.hashCode(value) == value?

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@tianchen92 tianchen92 Jul 18, 2019

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I see, you are right, thanks, fixed.

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This looks like a good start do you see performance improvements? If so I think the next step would be to add unit tests.

Also, CC @praveenbingo and @pravindra to make sure they don't have concerns with the new interfaces.

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tianchen92 commented Jul 16, 2019 •
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This looks like a good start do you see performance improvements? If so I think the next step would be to add unit tests.

Also, CC @praveenbingo and @pravindra to make sure they don't have concerns with the new interfaces.

Sure, I have already added a DictionaryEncoderBenchmark and list its previous performance data in #4786.
The performance improvement with this PR is as below:
DictionaryEncoderBenchmarks#testEncode:
Before: 5 415703.943 ± 9258.049 ns/op
After: 5 386094.115 ± 19138.808 ns/op

And add what kind of UT? now TestDictionaryVector already support many types like Struct, List, Binary, Varchar etc.

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emkornfield commented Jul 19, 2019

Sorry forgot about the existing unit tests. LGTM.

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emkornfield commented Jul 19, 2019

+1, than you

kszucs pushed a commit that referenced this pull request Jul 22, 2019
@tianchen92 @kszucs
ARROW-5902: [Java] Implement hash table and equals & hashCode API for…
88caa6b 
… dictionary encoding

As discussed in #4792

Implement a hash table to only store hash & index, meanwhile add check equal function in ValueVector API.

Author: tianchen <[email protected]>

Closes #4846 from tianchen92/hasher and squashes the following commits:

2db7302 <tianchen> fix
5facc2a <tianchen> resolve comments
175192a <tianchen> fix test and style
7a87526 <tianchen> implementation of equals and hashCode
c89608b <tianchen> fix
8f2e1a2 <tianchen> hash table prototype
@tianchen92 tianchen92 mentioned this pull request Aug 10, 2019
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@asfimport asfimport mentioned this pull request Aug 1, 2019
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pribor pushed a commit to GlobalWebIndex/arrow that referenced this pull request Oct 24, 2025
@tianchen92 @kou
ARROW-5902: [Java] Implement hash table and equals & hashCode API for…
0f3dd97 
… dictionary encoding

As discussed in apache#4792

Implement a hash table to only store hash & index, meanwhile add check equal function in ValueVector API.

Author: tianchen <[email protected]>

Closes apache#4846 from tianchen92/hasher and squashes the following commits:

2db7302 <tianchen> fix
5facc2a <tianchen> resolve comments
175192a <tianchen> fix test and style
7a87526 <tianchen> implementation of equals and hashCode
c89608b <tianchen> fix
8f2e1a2 <tianchen> hash table prototype
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