[ https://issues.apache.org/jira/browse/PARQUET-980?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Cheng Lian updated PARQUET-980: ------------------------------- Affects Version/s: 1.8.1 1.8.2 > Cannot read row group larger than 2GB > ------------------------------------- > > Key: PARQUET-980 > URL: https://issues.apache.org/jira/browse/PARQUET-980 > Project: Parquet > Issue Type: Bug > Components: parquet-mr > Affects Versions: 1.8.0, 1.8.1, 1.8.2 > Reporter: Herman van Hovell > > Parquet MR 1.8.2 does not support reading row groups which are larger than 2 > GB. > See:https://github.com/apache/parquet-mr/blob/parquet-1.8.x/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileReader.java#L1064 > We are seeing this when writing skewed records. This throws off the > estimation of the memory check interval in the InternalParquetRecordWriter. > The following spark code illustrates this: > {noformat} > /** > * Create a data frame that will make parquet write a file with a row group > larger than 2 GB. Parquet > * only checks the size of the row group after writing a number of records. > This number is based on > * average row size of the already written records. This is problematic in > the following scenario: > * - The initial (100) records in the record group are relatively small. > * - The InternalParquetRecordWriter checks if it needs to write to disk (it > should not), it assumes > * that the remaining records have a similar size, and (greatly) increases > the check interval (usually > * to 10000). > * - The remaining records are much larger then expected, making the row > group larger than 2 GB (which > * makes reading the row group impossible). > * > * The data frame below illustrates such a scenario. This creates a row group > of approximately 4GB. > */ > val badDf = spark.range(0, 2200, 1, 1).mapPartitions { iterator => > var i = 0 > val random = new scala.util.Random(42) > val buffer = new Array[Char](750000) > iterator.map { id => > // the first 200 records have a length of 1K and the remaining 2000 have > a length of 750K. > val numChars = if (i < 200) 1000 else 750000 > i += 1 > // create a random array > var j = 0 > while (j < numChars) { > // Generate a char (borrowed from scala.util.Random) > buffer(j) = (random.nextInt(0xD800 - 1) + 1).toChar > j += 1 > } > // create a string: the string constructor will copy the buffer. > new String(buffer, 0, numChars) > } > } > badDf.write.parquet("somefile") > val corruptedDf = spark.read.parquet("somefile") > corruptedDf.select(count(lit(1)), max(length($"value"))).show() > {noformat} > The latter fails with the following exception: > {noformat} > java.lang.NegativeArraySizeException > at > org.apache.parquet.hadoop.ParquetFileReader$ConsecutiveChunkList.readAll(ParquetFileReader.java:1064) > at > org.apache.parquet.hadoop.ParquetFileReader.readNextRowGroup(ParquetFileReader.java:698) > ... > {noformat} > This seems to be fixed by commit > https://github.com/apache/parquet-mr/commit/6b605a4ea05b66e1a6bf843353abcb4834a4ced8 > in parquet 1.9.x. Is there any chance that we can fix this in 1.8.x? > This can happen when -- This message was sent by Atlassian JIRA (v6.3.15#6346)