.. Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

..    http://www.apache.org/licenses/LICENSE-2.0

.. Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

`Iceberg`_
==========

Apache Iceberg is an open table format for huge analytic datasets.
Iceberg adds tables to compute engines including Spark, Trino, PrestoDB, Flink, Hive and Impala
using a high-performance table format that works just like a SQL table.

.. tip::
   This article assumes that you have mastered the basic knowledge and operation of `Iceberg`_.
   For the knowledge about Iceberg not mentioned in this article,
   you can obtain it from its `Official Documentation`_.

By using kyuubi, we can run SQL queries towards Iceberg which is more
convenient, easy to understand, and easy to expand than directly using
hive to manipulate Iceberg.

Iceberg Integration
-------------------

To enable the integration of kyuubi hive sql engine and Iceberg, you need to:

- Referencing the Iceberg :ref:`dependencies<hive-iceberg-deps>`
- Setting the hive extension and catalog :ref:`configurations<hive-iceberg-conf>`

.. _hive-iceberg-deps:

Dependencies
************

The **classpath** of kyuubi hive sql engine with Iceberg supported consists of

1. kyuubi-hive-sql-engine-\ |release|\ _2.12.jar, the engine jar deployed with Kyuubi distributions
2. a copy of hive distribution
3. iceberg-hive-runtime-<hive.version>_<scala.version>-<iceberg.version>.jar (example: iceberg-hive-runtime-3.2_2.12-0.14.0.jar), which can be found in the `Maven Central`_

In order to make the Iceberg packages visible for the runtime classpath of engines, we can use the method:

1. Execute ADD JAR statement in the Kyuubi to add dependencies to Hive’s auxiliary classpath. For example:

.. code-block:: sql

   ADD JAR /path/to/iceberg-hive-runtime.jar;

.. warning::
   Please mind the compatibility of different Iceberg and Hive versions, which can be confirmed on the page of `Iceberg multi engine support`_.

.. _hive-iceberg-conf:

Configurations
**************

To activate functionality of Iceberg, we can set the following configurations:
Set ``iceberg.engine.hive.enabled=true`` in the Hadoop configuration. For example, setting this in the hive-site.xml

Iceberg Operations
------------------

Taking ``CREATE TABLE`` as a example,

.. code-block:: sql

   CREATE TABLE x (i int) STORED BY 'org.apache.iceberg.mr.hive.HiveIcebergStorageHandler';
   CREATE EXTERNAL TABLE x (i int) STORED BY 'org.apache.iceberg.mr.hive.HiveIcebergStorageHandler';

Taking ``SELECT`` as a example,

.. code-block:: sql

   SELECT * FROM foo;

Taking ``INSERT`` as a example,

.. code-block:: sql

   INSERT INTO foo VALUES (1, 'a'), (2, 'b'), (3, 'c');
   INSERT OVERWRITE TABLE target SELECT * FROM source;

Taking ``ALTER`` as a example,

.. code-block:: sql

   ALTER TABLE t SET TBLPROPERTIES('...'='...');


.. _Iceberg: https://iceberg.apache.org/
.. _Official Documentation: https://iceberg.apache.org/docs/latest/
.. _Maven Central: https://mvnrepository.com/artifact/org.apache.iceberg
.. _Iceberg multi engine support: https://iceberg.apache.org/multi-engine-support/