[#2348] Improvement(docs): Add user doc for relational entity store

docs/how-to-install.md

@@ -43,7 +43,8 @@ The Gravitino binary distribution package contains the following files:
     |   └── log4j2.properties       # log4j configuration for the Gravitino server.
     |── libs/                       # Gravitino server dependencies libraries.
     |── logs/                       # Gravitino server logs. Automatically created after the Gravitino server starts.
-    └── data/                       # Default directory for the Gravitino server to store data.
+    |── data/                       # Default directory for the Gravitino server to store data.
+    └── scripts/                    # Extra scripts for Gravitino.
 ```
 
 #### Configure the Gravitino server

docs/how-to-use-relational-entity-storage.md

@@ -0,0 +1,80 @@
+---
+title: How to use relational entity storage
+slug: /how-to-use-relational-entity-storage
+license: "Copyright 2024 Datastrato Pvt Ltd.
+This software is licensed under the Apache License version 2."
+---
+
+## Introduction
+
+Gravitino supports using `Relational Entity Storage` to store metadata after the version `0.5.0`.  
+
+### What is Relational Entity Storage
+Before the version `0.5.0`, Gravitino only supports `KV Entity Storage` to store metadata.
+`Relational Entity Storage` is an entity storage implementation that is compatible with `KV Entity Storage` at the interface layer and uses relational databases as the metadata backend storage.
+
+### Target users
+`Relational Entity Storage` is mainly aimed at users who are accustomed to using `RDBMS` to store data or lack available a KV storage, and want to use Gravitino.  
+
+### Advantages
+With `Relational Entity Storage`, you can quickly deploy Gravitino in a production environment and take advantage of relational storage to manage metadata.  
+
+### What kind of backend storage are supported
+Currently, `Relational Entity Storage` supports the `JDBC Backend`, and it uses `MySQL` as the default storage for `JDBC Backend`.
+
+
+## Steps for usage
+
+### Prerequisites
+
++ MySQL 5.7 or 8.0
++ Gravitino distribution package
++ MySQL connector Jar (Should be compatible with the version of MySQL instance)
+
+### Step 1: Get the initialization script
+
+You need `download` and `unzip` the distribution package firstly, please see: [How to install Gravitino](how-to-install.md).
+Then you can get the initialization script in the directory:
+```text
+${distribution_package_directory}/scripts/mysql/
+```
+The script names like `schema-{version}-mysql.sql`, and the `version` depends on your Gravitino version.  
+For example, if your Gravitino version is `0.5.0`, then you should choose the `schema-0.5.0-mysql.sql` script.
+
+### Step 2: Initialize the database
+
+Please `create a database` in MySQL in advance, and `execute` the initialization script obtained above in the database.
+
+### Step 3: Place the MySQL connector Jar
+
+You should `download` the MySQL connector Jar for the corresponding version of MySQL you use (You can download it from the [maven-central-repo](https://repo1.maven.org/maven2/mysql/mysql-connector-java/)), which names like `mysql-connector-java-{driver-version}.jar`.  
+Then please place it in the distribution package directory:
+```text
+${distribution_package_directory}/libs/
+```
+
+### Step 4: Set up the Gravitino server configs
+
+Find the server configuration file names `gravitino.conf` in the distribution package directory:
+
+```text
+${distribution_package_directory}/conf/
+```
+Then set up the following server configs:
+```text
+gravitino.entity.store = relational
+gravitino.entity.store.relational = JDBCBackend
+gravitino.entity.store.relational.jdbcUrl = ${your_jdbc_url}
+gravitino.entity.store.relational.jdbcDriver = ${your_driver_name}
+gravitino.entity.store.relational.jdbcUser = ${your_username}
+gravitino.entity.store.relational.jdbcPassword = ${your_password}
+```
+
+### Step 5: Start the server
+
+Finally, you can run the script in the distribution package directory to start the server:
+
+```shell
+./${distribution_package_directory}/bin/gravitino.sh start
+```
+