[PARQUET-152] Encoding issue with fixed length byte arrays

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.8.0
• Component/s: parquet-mr
• Assignee: Sergio Peña
• Reporter: Nezih Yigitbasi
• Created: 18/Dec/14 00:12
• Updated: 23/Jun/24 03:27
• Resolved: 03/Jul/15 17:52

Description

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:

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]

But then read fails with the following exception:

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

When the array's size is < dictionaryPageSize, RLE_DICTIONARY encoding is used and read works fine:

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}

Issue Links

• causes: PARQUET-2231 [Format] Encoding spec incorrect for DELTA_BYTE_ARRAY
• links to: PR-225