rdblue commented on a change in pull request #2544: URL: https://github.com/apache/iceberg/pull/2544#discussion_r624755589
########## File path: site/docs/hive.md ########## @@ -17,117 +17,297 @@ # Hive -## Hive read support -Iceberg supports the reading of Iceberg tables from [Hive](https://hive.apache.org) by using a [StorageHandler](https://cwiki.apache.org/confluence/display/Hive/StorageHandlers). Please note that only Hive 2.x versions are currently supported. +Iceberg supports reading and writing Iceberg tables through [Hive](https://hive.apache.org) by using a [StorageHandler](https://cwiki.apache.org/confluence/display/Hive/StorageHandlers). +Here is the current compatibility matrix for Iceberg Hive support: -### Table creation -This section explains the various steps needed in order to overlay a Hive table "on top of" an existing Iceberg table. Iceberg tables are created using either a [`Catalog`](./javadoc/master/index.html?org/apache/iceberg/catalog/Catalog.html) or an implementation of the [`Tables`](./javadoc/master/index.html?org/apache/iceberg/Tables.html) interface and Hive needs to be configured accordingly to read data from these different types of table. +| Feature | Hive 2.x | Hive 3.1.2 | +| ------------------------ | ---------------------- | ---------------------- | +| CREATE EXTERNAL TABLE | ✔️ | ✔️ | +| CREATE TABLE | ✔️ | ✔️ | +| DROP TABLE | ✔️ | ✔️ | +| SELECT | ✔️ (MapReduce and Tez) | ✔️ (MapReduce and Tez) | +| INSERT INTO | ✔️ (MapReduce only)️ | ✔️ (MapReduce only) | -#### Add the Iceberg Hive Runtime jar file to the Hive classpath -Regardless of the table type, the `HiveIcebergStorageHandler` and supporting classes need to be made available on Hive's classpath. These are provided by the `iceberg-hive-runtime` jar file. For example, if using the Hive shell, this can be achieved by issuing a statement like so: -```sql -add jar /path/to/iceberg-hive-runtime.jar; -``` -There are many others ways to achieve this including adding the jar file to Hive's auxiliary classpath (so it is available by default) - please refer to Hive's documentation for more information. +## Enabling Iceberg support in Hive -#### Using Hadoop Tables -Iceberg tables created using `HadoopTables` are stored entirely in a directory in a filesystem like HDFS. +### Loading runtime jar -##### Create an Iceberg table -The first step is to create an Iceberg table using the Spark/Java/Python API and `HadoopTables`. For the purposes of this documentation we will assume that the table is called `table_a` and that the table location is `hdfs://some_path/table_a`. +To enable Iceberg support in Hive, the `HiveIcebergStorageHandler` and supporting classes need to be made available on Hive's classpath. +These are provided by the `iceberg-hive-runtime` jar file. +For example, if using the Hive shell, this can be achieved by issuing a statement like so: -##### Create a Hive table -Now overlay a Hive table on top of this Iceberg table by issuing Hive DDL like so: -```sql -CREATE EXTERNAL TABLE table_a -STORED BY 'org.apache.iceberg.mr.hive.HiveIcebergStorageHandler' -LOCATION 'hdfs://some_bucket/some_path/table_a'; ``` - -#### Query the Iceberg table via Hive -You should now be able to issue Hive SQL `SELECT` queries using the above table and see the results returned from the underlying Iceberg table. -```sql -SELECT * from table_a; +add jar /path/to/iceberg-hive-runtime.jar; ``` -#### Using Hive Catalog -Iceberg tables created using `HiveCatalog` are automatically registered with Hive. +There are many others ways to achieve this including adding the jar file to Hive's auxiliary classpath so it is available by default. +Please refer to Hive's documentation for more information. -##### Create an Iceberg table -The first step is to create an Iceberg table using the Spark/Java/Python API and `HiveCatalog`. For the purposes of this documentation we will assume that the table is called `table_b` and that the table location is `s3://some_path/table_b`. In order for Iceberg to correctly set up the Hive table for querying some configuration values need to be set, the two options for this are described below - you can use either or the other depending on your use case. +### Enabling support + +#### Hadoop configuration + +The value `iceberg.engine.hive.enabled` needs to be set to `true` in the Hadoop configuration in the environment. +For example, it can be added to the Hive configuration file on the classpath of the application creating or modifying (altering, inserting etc.) the table by modifying the relevant `hive-site.xml`. +You can also do it programmatically like so: -##### Hive Configuration -The value `iceberg.engine.hive.enabled` needs to be set to `true` and added to the Hive configuration file on the classpath of the application creating or modifying (altering, inserting etc.) the table. This can be done by modifying the relevant `hive-site.xml`. Alternatively this can be done programmatically like so: ```java Configuration hadoopConfiguration = spark.sparkContext().hadoopConfiguration(); -hadoopConfiguration.set(ConfigProperties.ENGINE_HIVE_ENABLED, "true"); //iceberg.engine.hive.enabled=true +hadoopConfiguration.set(ConfigProperties.ENGINE_HIVE_ENABLED, "true"); // iceberg.engine.hive.enabled=true HiveCatalog catalog = new HiveCatalog(hadoopConfiguration); ... catalog.createTable(tableId, schema, spec); ``` -##### Table Property Configuration -The property `engine.hive.enabled` needs to be set to `true` and added to the table properties when creating the Iceberg table. This can be done like so: +#### Table property configuration + +Alternatively, the property `engine.hive.enabled` can be set to `true` and added to the table properties when creating the Iceberg table. +Here is an example of doing it programmatically: + ```java - Map<String, String> tableProperties = new HashMap<String, String>(); - tableProperties.put(TableProperties.ENGINE_HIVE_ENABLED, "true"); //engine.hive.enabled=true - catalog.createTable(tableId, schema, spec, tableProperties); +Catalog catalog = ...; +Map<String, String> tableProperties = Maps.newHashMap(); +tableProperties.put(TableProperties.ENGINE_HIVE_ENABLED, "true"); // engine.hive.enabled=true +catalog.createTable(tableId, schema, spec, tableProperties); ``` -#### Query the Iceberg table via Hive -In order to query a Hive table created by either of the HiveCatalog methods described above you need to first set a Hive configuration value like so: -```sql -SET iceberg.mr.catalog=hive; +The table level configuration overwrites the global Hadoop configuration. + +## Iceberg and Hive catalog compatibility + +### Global Hive catalog + +From the Hive engine's perspective, there is only 1 global data catalog, which is the Hive metastore defined in the Hadoop configuration in the runtime environment. Review comment: Nits: "one" instead of "1" and "that is defined . . ." rather than ", which is the Hive metastore defined . . ." -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
