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https://issues.apache.org/jira/browse/HIVE-16559?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16001148#comment-16001148
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Barna Zsombor Klara commented on HIVE-16559:
--------------------------------------------
I ran the same test as in the Jira description but with ORC as the file format
and HIVE_SCHEMA_EVOLUTION set to false and ended up with:{{Error:
java.io.IOException: java.lang.ClassCastException:
org.apache.hadoop.io.IntWritable cannot be cast to org.apache.hadoop.io.Text
(state=,code=0)}} when trying to select from the altered table.
I don't think ORC supports this either.
But then again I don't really understand that check for ORC, how does setting
HIVE_SCHEMA_EVOLUTION to false end up with a "supported" mode for schema
evolution?
> Parquet schema evolution for partitioned tables may break if table and
> partition serdes differ
> ----------------------------------------------------------------------------------------------
>
> Key: HIVE-16559
> URL: https://issues.apache.org/jira/browse/HIVE-16559
> Project: Hive
> Issue Type: Bug
> Components: Serializers/Deserializers
> Reporter: Barna Zsombor Klara
> Assignee: Barna Zsombor Klara
> Fix For: 3.0.0
>
> Attachments: HIVE-16559.01.patch
>
>
> Parquet schema evolution should make it possible to have partitions/tables
> backed by files with different schemas. Hive should match the table columns
> with file columns based on the column name if possible.
> However if the serde for a table is missing columns from the serde of a
> partition Hive fails to match the columns together.
> Steps to reproduce:
> {code}
> CREATE TABLE myparquettable_parted
> (
> name string,
> favnumber int,
> favcolor string,
> age int,
> favpet string
> )
> PARTITIONED BY (day string)
> STORED AS PARQUET;
> INSERT OVERWRITE TABLE myparquettable_parted
> PARTITION(day='2017-04-04')
> SELECT
> 'mary' as name,
> 5 AS favnumber,
> 'blue' AS favcolor,
> 35 AS age,
> 'dog' AS favpet;
> alter table myparquettable_parted
> REPLACE COLUMNS
> (
> favnumber int,
> age int
> ); <!--- No cascade option, so the partition will not be altered.
> {code}
> {{SELECT * FROM myparquettable_parted where day='2017-04-04';}}
> will fail with:
> {{java.lang.UnsupportedOperationException: Cannot inspect
> org.apache.hadoop.io.IntWritable}}
> Hive should either match the columns together or prevent the user from
> dropping columns from the table.
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