I'm looking for a way to modify a parquet data table in HIVE to remove some fields. The table is managed but it doesn't matter because I can convert it to external.
The problem is that I can not use the command ALTER TABLE ... REPLACE COLUMN with partitioned parquet tables.
It is works well for textfile format (partitioned or not) and only for non-partitioned parquet tables.
I've tried to replace column but this is the result:
hive> ALTER TABLE db_test.mytable REPLACE COLUMNS(name String);
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask.
Replacing columns cannot drop columns for table db_test.mytable.
SerDe may be incompatible
I've thought about some solutions, but none of them fits my scenario:
First
- [Optional] Convert the table in external.
- Delete the table.
- Re-create the table with the fields that I want.
- MSCK REPAIR TABLE to add HDFS partitions.
- [Optional] Convert back to managed table.
Second
- Create temporary table as selection of the original table with the fields that I choose.
- Delete the original table.
- Rename the temporary table to the original name.
Both options affect my process because I would lose the statistics of my table. This table is consumed with MicroStrategy by Impala and I need to mantain the statistics.
In addition, the second solution is bad with very large data tables.
Any suggestions?
Thanks in advance.
