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https://issues.apache.org/jira/browse/SPARK-4781?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Armbrust resolved SPARK-4781.
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Resolution: Won't Fix
This is by design, the alter table command in hive only changes metadata. From
the HiveQL guide:
{code}
The column change command will only modify Hive's metadata, and will not modify
data. Users should make sure the actual data layout of the table/partition
conforms with the metadata definition.
{code}
If you want to change column names for parquet data you would need to create a
VIEW on the base table.
> Column values become all NULL after doing ALTER TABLE CHANGE for renaming
> column names (Parquet external table in HiveContext)
> ------------------------------------------------------------------------------------------------------------------------------
>
> Key: SPARK-4781
> URL: https://issues.apache.org/jira/browse/SPARK-4781
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 1.2.0, 1.3.0, 1.2.1
> Reporter: Jianshi Huang
>
> I have a table say created like follows:
> {code}
> CREATE EXTERNAL TABLE pmt (
> `sorted::cre_ts` string
> )
> STORED AS PARQUET
> LOCATION '...'
> {code}
> And I renamed the column from sorted::cre_ts to cre_ts by doing:
> {code}
> ALTER TABLE pmt CHANGE `sorted::cre_ts` cre_ts string
> {code}
> After renaming the column, the values in the column become all NULLs.
> {noformat}
> Before renaming:
> scala> sql("select `sorted::cre_ts` from pmt limit 1").collect
> res12: Array[org.apache.spark.sql.Row] = Array([12/02/2014 07:38:54])
> Execute renaming:
> scala> sql("alter table pmt change `sorted::cre_ts` cre_ts string")
> res13: org.apache.spark.sql.SchemaRDD =
> SchemaRDD[972] at RDD at SchemaRDD.scala:108
> == Query Plan ==
> <Native command: executed by Hive>
> After renaming:
> scala> sql("select cre_ts from pmt limit 1").collect
> res16: Array[org.apache.spark.sql.Row] = Array([null])
> {noformat}
> Jianshi
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