Sergio Peña created HIVE-8065:
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Summary: Support HDFS encryption functionality on Hive
Key: HIVE-8065
URL: https://issues.apache.org/jira/browse/HIVE-8065
Project: Hive
Issue Type: Improvement
Affects Versions: 0.13.1
Reporter: Sergio Peña
Assignee: Sergio Peña
The new encryption support on HDFS makes Hive incompatible and unusable when
this feature is used.
HDFS encryption is designed so that an user can configure different encryption
zones (or directories) for multi-tenant environments. An encryption zone has an
exclusive encryption key, such as AES-128 or AES-256. Because of security
compliance, the HDFS does not allow to move/rename files between encryption
zones. Renames are allowed only inside the same encryption zone. A copy is
allowed between encryption zones.
See HDFS-6134 for more details about HDFS encryption design.
Hive currently uses a scratch directory (like /tmp/$user/$random). This scratch
directory is used for the output of intermediate data (between MR jobs) and for
the final output of the hive query which is later moved to the table directory
location.
If Hive tables are in different encryption zones than the scratch directory,
then Hive won't be able to renames those files/directories, and it will make
Hive unusable.
To handle this problem, we can change the scratch directory of the
query/statement to be inside the same encryption zone of the table directory
location. This way, the renaming process will be successful.
Also, for statements that move files between encryption zones (i.e. LOAD DATA),
a copy may be executed instead of a rename. This will cause an overhead when
copying large data files, but it won't break the encryption on Hive.
Another security thing to consider is when using joins selects. If Hive joins
different tables with different encryption key strengths, then the results of
the select might break the security compliance of the tables. Let's say two
tables with 128 bits and 256 bits encryption are joined, then the temporary
results might be stored in the 128 bits encryption zone. This will conflict
with the table encrypted with 256 bits temporary.
To fix this, Hive should be able to select the scratch directory that is more
secured/encrypted in order to save the intermediate data temporary with no
compliance issues.
For instance:
{noformat}
SELECT * FROM table-aes128 t1 JOIN table-aes256 t2 WHERE t1.id == t2.id;
{noformat}
- This should use a scratch directory (or staging directory) inside the
table-aes256 table location.
{noformat}
INSERT OVERWRITE TABLE table-unencrypted SELECT * FROM table-aes1;
{noformat}
- This should use a scratch directory inside the table-aes1 location.
{noformat}
FROM table-unencrypted
INSERT OVERWRITE TABLE table-aes128 SELECT id, name
INSERT OVERWRITE TABLE table-aes256 SELECT id, name
{noformat}
- This should use a scratch directory on each of the tables locations.
- The first SELECT will have its scratch directory on table-aes128 directory.
- The second SELECT will have its scratch directory on table-aes256 directory.
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