Karan Datta created IMPALA-8953:
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Summary: Tables and Databases sharing same name can cause query
failures if table is not readable by Impala
Key: IMPALA-8953
URL: https://issues.apache.org/jira/browse/IMPALA-8953
Project: IMPALA
Issue Type: Improvement
Reporter: Karan Datta
Please see below scenario:
1) CREATE DATABASE a;
2) Create tables "a.b" and "default.a". However, create "default.a" in a format
which Impala cannot read. For example: Open CSV Serde from Hive.
3) Connect to Impala and execute below statements -
a) INVALIDATE METADATA;
b) use default;
c) select * from a.b;
Above query will lead to following exception:
CAUSED BY: TableLoadingException: Unrecognized table type for table: default.a
If the database of query "select * from a.b;" is changed to any other database
then, the query executes successfully. For example:
use test1 or use test;
select * from a.b;
Also, if the table "default.a" is created with a format that Impala can
read/load, query "select * from a.b" executes successfully.
Above scenario occurs as Impala can refer to the collection column b in table a
in database default, or it can refer to table b in database a. As Impala cannot
disambiguate between the two cases unless it knows that there is a collection
column b be in default.a, it loads metadata of table "default.a" while
executing query on table "a.b". If the table "default.a" exists and is not
readable by Impala, any query executed on tables available in database "a" from
default database will fail. For a better UX, we should improve/change this
behavior.
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