HDDS-11947. [Docs] [User Guide] Impala Integration.

hadoop-hdds/docs/content/integration/Impala.md

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+---
+title: Impala
+weight: 4
+menu:
+   main:
+      parent: "Application Integrations"
+---
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+
+Starting with version 4.2.0, Apache Impala provides full support for querying data stored in Apache Ozone. To utilize this functionality, ensure that your Ozone version is 1.4.0 or later.
+
+## Supported Access Protocols
+
+Impala supports the following protocols for accessing Ozone data:
+
+* ofs
+* s3a
+
+Note: The o3fs protocol is **NOT** supported by Impala.
+
+## Supported Replication Types
+
+Impala is compatible with Ozone buckets configured with either:
+
+* RATIS (Replication)
+* Erasure Coding
+
+## Querying Ozone Data with Impala
+
+Impala provides two approaches to interact with Ozone:
+
+* Managed Tables
+* External Tables
+
+### Managed Tables
+
+If the Hive Warehouse Directory is located in Ozone, you can execute Impala queries without any changes, treating the Ozone file system like HDFS. For example:
+
+```sql
+CREATE DATABASE d1;
+```
+
+```sql
+CREATE TABLE t1 (x INT, s STRING);
+```
+
+The data will be stored under the Hive Warehouse Directory path in Ozone.
+
+#### Specifying a Custom Ozone Path
+
+You can create managed databases, tables, or partitions at a specific Ozone path using the `LOCATION` clause. Example:
+
+```sql
+CREATE DATABASE d1 LOCATION 'ofs://ozone1/vol1/bucket1/d1.db';
+```
+
+```sql
+CREATE TABLE t1 LOCATION 'ofs://ozone1/vol1/bucket1/table1';
+```
+
+### External Tables
+
+You can create an external table in Impala to query Ozone data. For example:
+
+```sql
+CREATE EXTERNAL TABLE external_table (
+  id INT,
+  name STRING
+)
+LOCATION 'ofs://ozone1/vol1/bucket1/table1';
+```
+
+* With external tables, the data is expected to be created and managed by another tool.
+* Impala queries the data as-is.
+* The metadata is stored under the external warehouse directory.
+* Note: Dropping an external table in Impala does not delete the associated data.
+
+
+## Using the S3A Protocol
+
+In addition to ofs, Impala can access Ozone via the S3 Gateway using the S3A file system. For more details, refer to 
+* The [S3 Protocol]({{< ref "interface/S3.md">}})
+* The [Hadoop S3A](https://hadoop.apache.org/docs/current/hadoop-aws/tools/hadoop-aws/index.html) documentation.
+
+For additional information, consult the Apache Impala User Documentation
+[Using Impala with Apache Ozone Storage](https://impala.apache.org/docs/build/html/topics/impala_ozone.html).