docs/connector/spark/iceberg.rst

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`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
spark to manipulate Iceberg.

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

To enable the integration of Kyuubi Spark SQL engine and Iceberg through
Spark DataSource V2 API, you need to:

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

.. _spark-iceberg-deps:

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

The **classpath** of Kyuubi Spark SQL engine with Iceberg supported consists of

1. kyuubi-spark-sql-engine-\ |release|\ _2.12.jar, the engine jar deployed with a Kyuubi distribution
2. a copy of Spark distribution
3. iceberg-spark-runtime-<spark.version>_<scala.version>-<iceberg.version>.jar (example: iceberg-spark-runtime-3.5_2.12-1.7.0.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 one of these methods:

1. Put the Iceberg packages into ``$SPARK_HOME/jars`` directly
2. Set ``spark.jars=/path/to/iceberg-spark-runtime``

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

.. _spark-iceberg-conf:

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

To activate functionality of Iceberg, we can set the following configurations:

.. code-block:: properties

   spark.sql.catalog.spark_catalog=org.apache.iceberg.spark.SparkCatalog
   spark.sql.catalog.spark_catalog.type=hive
   spark.sql.catalog.spark_catalog.uri=thrift://metastore-host:port
   spark.sql.extensions=org.apache.iceberg.spark.extensions.IcebergSparkSessionExtensions

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

Taking ``CREATE TABLE`` as a example,

.. code-block:: sql

   CREATE TABLE foo (
     id bigint COMMENT 'unique id',
     data string)
   USING iceberg;

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');

Taking ``UPDATE`` as a example, Spark 3.1 added support for UPDATE queries that update matching rows in tables.

.. code-block:: sql

   UPDATE foo SET data = 'd', id = 4 WHERE id >= 3 and id < 4;

Taking ``DELETE FROM`` as a example, Spark 3 added support for DELETE FROM queries to remove data from tables.

.. code-block:: sql

   DELETE FROM foo WHERE id >= 1 and id < 2;

Taking ``MERGE INTO`` as a example,

.. code-block:: sql

   MERGE INTO target_table t
   USING source_table s
   ON t.id = s.id
   WHEN MATCHED AND s.opType = 'delete' THEN DELETE
   WHEN MATCHED AND s.opType = 'update' THEN UPDATE SET id = s.id, data = s.data
   WHEN NOT MATCHED AND s.opType = 'insert' THEN INSERT (id, data) VALUES (s.id, s.data);

.. _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/