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https://issues.apache.org/jira/browse/PARQUET-152?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17677297#comment-17677297
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Antoine Pitrou commented on PARQUET-152:
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It would be nice if the encodings spec had been updated as well, because for
now it mentions that DELTA_BYTE_ARRAY is only supported for BYTE_ARRAY columns,
not FIXED_LEN_BYTE_ARRAY. See PARQUET-2231.
> Encoding issue with fixed length byte arrays
> --------------------------------------------
>
> Key: PARQUET-152
> URL: https://issues.apache.org/jira/browse/PARQUET-152
> Project: Parquet
> Issue Type: Bug
> Reporter: Nezih Yigitbasi
> Assignee: Sergio Peña
> Priority: Minor
> Fix For: 1.8.0
>
>
> While running some tests against the master branch I hit an encoding issue
> that seemed like a bug to me.
> I noticed that when writing a fixed length byte array and the array's size is
> > dictionaryPageSize (in my test it was 512), the encoding falls back to
> DELTA_BYTE_ARRAY as seen below:
> {noformat}
> Dec 17, 2014 3:41:10 PM INFO: parquet.hadoop.ColumnChunkPageWriteStore:
> written 12,125B for [flba_field] FIXED_LEN_BYTE_ARRAY: 5,000 values, 1,710B
> raw, 1,710B comp, 5 pages, encodings: [DELTA_BYTE_ARRAY]
> {noformat}
> But then read fails with the following exception:
> {noformat}
> Caused by: parquet.io.ParquetDecodingException: Encoding DELTA_BYTE_ARRAY is
> only supported for type BINARY
> at parquet.column.Encoding$7.getValuesReader(Encoding.java:193)
> at
> parquet.column.impl.ColumnReaderImpl.initDataReader(ColumnReaderImpl.java:534)
> at
> parquet.column.impl.ColumnReaderImpl.readPageV2(ColumnReaderImpl.java:574)
> at
> parquet.column.impl.ColumnReaderImpl.access$400(ColumnReaderImpl.java:54)
> at
> parquet.column.impl.ColumnReaderImpl$3.visit(ColumnReaderImpl.java:518)
> at
> parquet.column.impl.ColumnReaderImpl$3.visit(ColumnReaderImpl.java:510)
> at parquet.column.page.DataPageV2.accept(DataPageV2.java:123)
> at
> parquet.column.impl.ColumnReaderImpl.readPage(ColumnReaderImpl.java:510)
> at
> parquet.column.impl.ColumnReaderImpl.checkRead(ColumnReaderImpl.java:502)
> at
> parquet.column.impl.ColumnReaderImpl.consume(ColumnReaderImpl.java:604)
> at
> parquet.column.impl.ColumnReaderImpl.<init>(ColumnReaderImpl.java:348)
> at
> parquet.column.impl.ColumnReadStoreImpl.newMemColumnReader(ColumnReadStoreImpl.java:63)
> at
> parquet.column.impl.ColumnReadStoreImpl.getColumnReader(ColumnReadStoreImpl.java:58)
> at
> parquet.io.RecordReaderImplementation.<init>(RecordReaderImplementation.java:267)
> at parquet.io.MessageColumnIO$1.visit(MessageColumnIO.java:131)
> at parquet.io.MessageColumnIO$1.visit(MessageColumnIO.java:96)
> at
> parquet.filter2.compat.FilterCompat$NoOpFilter.accept(FilterCompat.java:136)
> at parquet.io.MessageColumnIO.getRecordReader(MessageColumnIO.java:96)
> at
> parquet.hadoop.InternalParquetRecordReader.checkRead(InternalParquetRecordReader.java:129)
> at
> parquet.hadoop.InternalParquetRecordReader.nextKeyValue(InternalParquetRecordReader.java:198)
> ... 16 more
> {noformat}
> When the array's size is < dictionaryPageSize, RLE_DICTIONARY encoding is
> used and read works fine:
> {noformat}
> Dec 17, 2014 3:39:50 PM INFO: parquet.hadoop.ColumnChunkPageWriteStore:
> written 50B for [flba_field] FIXED_LEN_BYTE_ARRAY: 5,000 values, 3B raw, 3B
> comp, 1 pages, encodings: [RLE_DICTIONARY, PLAIN], dic { 1 entries, 8B raw,
> 1B comp}
> {noformat}
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