Major Description
REPRO STEPS:
create database skewtest;
use skewtest;
create table skew (id bigint, acct string) skewed by (acct) on ('CC','CH');
create index skew_indx on table skew (id) as 'org.apache.hadoop.hive.ql.index.compact.CompactIndexHandler' WITH DEFERRED REBUILD;
Last DDL fails with following error.
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. InvalidObjectException(message:Invalid skew column [acct])
When creating a table, Hive has sanity tests to make sure the columns have proper names and the skewed columns are subset of the table columns. Here we fail because index table has skewed column info. Index tables's skewed columns include
{acct} and the columns are {id, _bucketname, _offsets}. As the skewed column {acct}is not part of the table columns Hive throws the exception.
The reason why Index table got skewed column info even though its definition has no such info is: When creating the index table a deep copy of the base table's StorageDescriptor (SD) (in this case 'skew') is made. And in that copied SD, index specific parameters are set and unrelated parameters are reset. Here skewed column info is not reset (there are few other params that are not reset). That's why the index table contains the skewed column info.
Fix: Instead of deep copying the base table StorageDescriptor, create a new one from gathered info. This way it avoids the index table to inherit unnecessary properties in SD from base table.