[AMORO-3404] Correct the description about MySQL usage

docs/admin-guides/deployment-on-kubernetes.md

@@ -156,17 +156,17 @@ ingress:
 
 ### Configure the database.
 
-AMS default is to use Derby database for storage. When the pod is destroyed, the data will also disappear.
-In production environments, we recommend using MySQL as the storage for system data.
+AMS uses embedded [Apache Derby](https://db.apache.org/derby/) as its backend storage by default.
+In production environments, we recommend using a RDBMS(Relational Database Management System) with higher availability guarantees as the storage for system data, you can ref to [Database Configuration](/deployment/#configure-system-database) for more detail.
 
 ```yaml
 amoroConf: 
   database:
-    type: mysql
-    driver: com.mysql.cj.jdbc.Driver
-    url: <jdbc-uri>
-    username: <mysql-user>
-    password: <mysql-password>
+    type: ${your_database_type}
+    driver: ${your_database_driver}
+    url: ${your_jdbc_url}
+    username: ${your_username}
+    password: ${your_password}
 ```
 
 
@@ -291,4 +291,4 @@ Notes:
 
 By default, the `serviceAccount` will be used to create the flink-optimizer. 
 Therefore, if you need to schedule the flink-optimizer across namespaces, 
-please create a `cluster-role` or use your own created `serviceAccount`.
+please create a `cluster-role` or use your own created `serviceAccount`.

docs/admin-guides/deployment.md

@@ -100,42 +100,26 @@ Make sure the port is not used before configuring it.
 
 ### Configure system database
 
-You can use MySQL/PostgreSQL as the system database instead of the default Derby.
+AMS uses embedded [Apache Derby](https://db.apache.org/derby/) as the backend storage by default, so you can use `Derby` directly without any additional configuration.
 
-If you would like to use MySQL as the system database, you need to manually download the [MySQL JDBC Connector](https://repo1.maven.org/maven2/com/mysql/mysql-connector-j/8.1.0/mysql-connector-j-8.1.0.jar)
-and move it into the `{AMORO_HOME}/lib/` directory. You can use the following command to complete these operations:
-```shell
-$ cd ${AMORO_HOME}
-$ MYSQL_JDBC_DRIVER_VERSION=8.0.30
-$ wget https://repo1.maven.org/maven2/mysql/mysql-connector-java/${MYSQL_JDBC_DRIVER_VERSION}/mysql-connector-java-${MYSQL_JDBC_DRIVER_VERSION}.jar
-$ mv mysql-connector-java-${MYSQL_JDBC_DRIVER_VERSION}.jar lib
-```
+You can also configure a relational backend storage as you needed.
 
-Create an empty database in MySQL/PostgreSQL, then AMS will automatically create tables in this MySQL/PostgreSQL database when it first started.
-If you want to create tables on yourself, set `ams.database.auto-create-tables` to false.
+> If you would like to use MySQL as the system database, you need to manually download the [MySQL JDBC Connector](https://repo1.maven.org/maven2/com/mysql/mysql-connector-j/8.1.0/mysql-connector-j-8.1.0.jar)
+and move it into the `${AMORO_HOME}/lib/` directory.
 
+You need to create an empty database in the RDBMS before to start the server, then AMS will automatically create tables in the database when it first started.
 
-One thing you need to do is Adding MySQL/PostgreSQL configuration under `config.yaml` of Ams:
+One thing you need to do is adding configuration under `config.yaml` of Ams:
 
 ```yaml
-# MySQL
 ams:
   database:
-    type: mysql
-    jdbc-driver-class: com.mysql.cj.jdbc.Driver
-    url: jdbc:mysql://127.0.0.1:3306/amoro?useUnicode=true&characterEncoding=UTF8&autoReconnect=true&useAffectedRows=true&allowPublicKeyRetrieval=true&useSSL=false
-    username: root
-    password: root
+    type: ${database_type} # postgres or mysql
+    jdbc-driver-class: ${your_driver_name}
+    url: ${your_jdbc_url}
+    username: ${your_username}
+    password: ${your_password}
     auto-create-tables: true
-# PostgreSQL
-#ams:
-#  database:
-#    type: postgres
-#    jdbc-driver-class: org.postgresql.Driver
-#    url: jdbc:postgresql://127.0.0.1:5432/amoro
-#    auto-create-tables: false
-#    username: user
-#    password: passwd
 ```
 
 ### Configure high availability
@@ -301,7 +285,7 @@ $ bin/ams.sh stop
 
 ### Upgrade system databases
 
-You can find all the upgrade SQL scripts under `{AMORO_HOME}/conf/mysql/` with name pattern `upgrade-a.b.c-to-x.y.z.sql`.
+You can find all the upgrade SQL scripts under `${AMORO_HOME}/conf/${db_type}/` with name pattern `upgrade-a.b.c-to-x.y.z.sql`.
 Execute the upgrade SQL scripts one by one to your system database based on your starting and target versions.
 
 ### Replace all libs and plugins

docs/concepts/catalogs.md

@@ -34,7 +34,7 @@ the multi-catalog feature can be used to support SQL across data sources, such a
 
 ```SQL
 SELECT c.ID, c.NAME, c.AGE, o.AMOUNT
-FROM MYSQL.ONLINE.CUSTOMERS c JOIN HIVE.OFFLINE.ORDERS o
+FROM ${CATALOG_A}.ONLINE.CUSTOMERS c JOIN ${CATALOG_B}.OFFLINE.ORDERS o
 ON (c.ID = o.CUSTOMER_ID)
 ```
 
@@ -67,4 +67,4 @@ Through metadata center and SQL-based federated computing of the computing engin
 such as DataOps and DataFabric
 - Automatic catalog detection: In compute engines like Spark and Flink, it is possible to automatically detect the creation and changes of a
 catalog, enabling a one-time configuration for permanent scalability.
-
+