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https://issues.apache.org/jira/browse/ARROW-3564?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Uwe L. Korn resolved ARROW-3564.
--------------------------------
Resolution: Fixed
Issue resolved by pull request 3331
[https://github.com/apache/arrow/pull/3331]
> [Python] writing version 2.0 parquet format with dictionary encoding enabled
> ----------------------------------------------------------------------------
>
> Key: ARROW-3564
> URL: https://issues.apache.org/jira/browse/ARROW-3564
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, Python
> Affects Versions: 0.11.0
> Reporter: Hatem Helal
> Assignee: Hatem Helal
> Priority: Major
> Labels: parquet, pull-request-available
> Fix For: 0.13.0
>
> Attachments: example_v1.0_dict_False.parquet,
> example_v1.0_dict_True.parquet, example_v2.0_dict_False.parquet,
> example_v2.0_dict_True.parquet, pyarrow_repro.py
>
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> Using pyarrow v0.11.0, the attached script writes a simple table (lifted from
> the [pyarrow doc|https://arrow.apache.org/docs/python/parquet.html]) to both
> parquet format versions 1.0 and 2.0, with and without dictionary encoding
> enabled.
> Inspecting the written files using
> [parquet-tools|https://github.com/apache/parquet-mr/tree/master/parquet-tools]
> appears to show that dictionary encoding is not used in either of the
> version 2.0 files. Both files report that the columns are encoded using
> {{PLAIN,RLE}} and that the dictionary page offset is zero. I was expecting
> that the column encoding would include {{RLE_DICTIONARY}}. Attached are the
> script with repro steps and the files that were generated by it.
> Below is the output of using {{parquet-tools meta}} on the version 2.0 files
> {panel:title=version='2.0', use_dictionary = True}
> {panel}
> |{{% parquet-tools meta example_v2.0_dict_True.parquet}}
> {{file:
> [file:.../example_v2.0_dict_True.parquet|file:///.../example_v2.0_dict_True.parquet]}}
> {{creator: parquet-cpp version 1.5.1-SNAPSHOT}} \{ Unknown macro:
> {extra}
> }}
>
> {{file schema: schema}}
>
> {{--------------------------------------------------------------------------------}}
> {{one: OPTIONAL DOUBLE R:0 D:1}}
> {{three: OPTIONAL BOOLEAN R:0 D:1}}
> {{two: OPTIONAL BINARY R:0 D:1}}
> {{__index_level_0__: OPTIONAL BINARY R:0 D:1}}
>
> {{row group 1: RC:3 TS:211 OFFSET:4}}
>
> {{--------------------------------------------------------------------------------}}
> {{one: DOUBLE SNAPPY DO:0 FPO:4 SZ:65/63/0.97 VC:3
> ENC:PLAIN,RLE ST:[min: -1.0, max: 2.5, num_nulls: 1]}}
> {{three: BOOLEAN SNAPPY DO:0 FPO:142 SZ:36/34/0.94 VC:3
> ENC:PLAIN,RLE ST:[min: false, max: true, num_nulls: 0]}}
> {{two: BINARY SNAPPY DO:0 FPO:225 SZ:60/58/0.97 VC:3
> ENC:PLAIN,RLE ST:[min: 0x626172, max: 0x666F6F, num_nulls: 0]}}
> {{__index_level_0__: BINARY SNAPPY DO:0 FPO:328 SZ:50/48/0.96 VC:3
> ENC:PLAIN,RLE ST:[min: 0x61, max: 0x63, num_nulls: 0]}}|
> {panel:title=version='2.0', use_dictionary = False}
> {panel}
> |{{% parquet-tools meta example_v2.0_dict_False.parquet}}
> {{file:
> [file:.../example_v2.0_dict_False.parquet|file:///.../example_v2.0_dict_False.parquet]}}
> {{creator: parquet-cpp version 1.5.1-SNAPSHOT}} \{ Unknown macro:
> {extra}
> }}
>
> {{file schema: schema}}
>
> {{--------------------------------------------------------------------------------}}
> {{one: OPTIONAL DOUBLE R:0 D:1}}
> {{three: OPTIONAL BOOLEAN R:0 D:1}}
> {{two: OPTIONAL BINARY R:0 D:1}}
> {{__index_level_0__: OPTIONAL BINARY R:0 D:1}}
>
> {{row group 1: RC:3 TS:211 OFFSET:4}}
>
> {{--------------------------------------------------------------------------------}}
> {{one: DOUBLE SNAPPY DO:0 FPO:4 SZ:65/63/0.97 VC:3
> ENC:PLAIN,RLE ST:[min: -1.0, max: 2.5, num_nulls: 1]}}
> {{three: BOOLEAN SNAPPY DO:0 FPO:142 SZ:36/34/0.94 VC:3
> ENC:PLAIN,RLE ST:[min: false, max: true, num_nulls: 0]}}
> {{two: BINARY SNAPPY DO:0 FPO:225 SZ:60/58/0.97 VC:3
> ENC:PLAIN,RLE ST:[min: 0x626172, max: 0x666F6F, num_nulls: 0]}}
> {{__index_level_0__: BINARY SNAPPY DO:0 FPO:328 SZ:50/48/0.96 VC:3
> ENC:PLAIN,RLE ST:[min: 0x61, max: 0x63, num_nulls: 0]}}|
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