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https://issues.apache.org/jira/browse/PARQUET-796?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15742687#comment-15742687
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Jakub Liska commented on PARQUET-796:
-------------------------------------
Certainly, it is a timestamp column, so the values have very high cardinality,
almost each value is unique unless there are records that occurred within the
same millisecond. So the delta encoding is the only suitable encoding for this
column I guess.
> Delta Encoding is not used when dictionary enabled
> --------------------------------------------------
>
> Key: PARQUET-796
> URL: https://issues.apache.org/jira/browse/PARQUET-796
> Project: Parquet
> Issue Type: Bug
> Components: parquet-mr
> Affects Versions: 1.9.0
> Reporter: Jakub Liska
> Priority: Critical
> Fix For: 1.9.1
>
>
> Current code doesn't enable using both Delta Encoding and Dictionary
> Encoding. If I instantiate ParquetWriter like this :
> {code}
> val writer = new ParquetWriter[Group](outFile, new GroupWriteSupport, codec,
> blockSize, pageSize, dictPageSize, enableDictionary = true, true,
> ParquetProperties.WriterVersion.PARQUET_2_0, configuration)
> {code}
> Then this piece of code :
> https://github.com/apache/parquet-mr/blob/master/parquet-column/src/main/java/org/apache/parquet/column/values/factory/DefaultValuesWriterFactory.java#L78-L86
> Causes that DictionaryValuesWriter is used instead of the inferred
> DeltaLongEncodingWriter.
> The original issue is here :
> https://github.com/apache/parquet-mr/pull/154#issuecomment-266489768
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