[jira] [Resolved] (SPARK-21392) Unable to infer schema when loading large Parquet file

["Hyukjin Kwon (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-21392?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hyukjin Kwon resolved SPARK-21392.
----------------------------------
    Resolution: Invalid

Let's start this on mailing list. I think we are lost around here about the actual issue.

> Unable to infer schema when loading large Parquet file
> ------------------------------------------------------
>
>                 Key: SPARK-21392
>                 URL: https://issues.apache.org/jira/browse/SPARK-21392
>             Project: Spark
>          Issue Type: Bug
>          Components: PySpark
>    Affects Versions: 2.1.1, 2.2.0
>         Environment: Spark 2.1.1. python 2.7.6
>            Reporter: Stuart Reynolds
>              Labels: parquet, pyspark
>
> The following boring code works up until when I read in the parquet file.
> {code:none}
> import numpy as np
> import pandas as pd
> import pyspark
> from pyspark import SQLContext, SparkContext, SparkConf
> print pyspark.__version__
> sc = SparkContext(conf=SparkConf().setMaster('local'))
> df = pd.DataFrame({"mi":np.arange(100), "eid":np.arange(100)})
> print df
> sqlc = SQLContext(sc)
> df = sqlc.createDataFrame(df)
> df = df.createOrReplaceTempView("outcomes")
> rdd = sqlc.sql("SELECT eid,mi FROM outcomes limit 5")
> print rdd.schema
> rdd.show()
> rdd.write.parquet("mi", mode="overwrite")
> rdd2 = sqlc.read.parquet("mi")  # FAIL!
> {code}
> {code:none}
> # print pyspark.__version__
> 2.2.0
> # print df
>     eid  mi
> 0     0   0
> 1     1   1
> 2     2   2
> 3     3   3
> ...
> [100 rows x 2 columns]
> # print rdd.schema
> StructType(List(StructField(eid,LongType,true),StructField(mi,LongType,true)))
> # rdd.show()
> +---+---+
> |eid| mi|
> +---+---+
> |  0|  0|
> |  1|  1|
> |  2|  2|
> |  3|  3|
> |  4|  4|
> +---+---+
> {code}
>     
> fails with:
> {code:none}
>     rdd2 = sqlc.read.parquet("mixx")
>   File "/usr/local/lib/python2.7/dist-packages/pyspark/sql/readwriter.py", line 291, in parquet
>     return self._df(self._jreader.parquet(_to_seq(self._spark._sc, paths)))
>   File "/usr/local/lib/python2.7/dist-packages/py4j/java_gateway.py", line 1133, in __call__
>     answer, self.gateway_client, self.target_id, self.name)
>   File "/usr/local/lib/python2.7/dist-packages/pyspark/sql/utils.py", line 69, in deco
>     raise AnalysisException(s.split(': ', 1)[1], stackTrace)
> pyspark.sql.utils.AnalysisException: u'Unable to infer schema for Parquet. It must be specified manually.;'
> {code}
> The documentation for parquet says the format is self describing, and the full schema was available when the parquet file was saved. What gives?
> Works with master='local', but fails with my cluster is specified.



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