diff --git a/README.md b/README.md
index 1e1d8c2..d1f2301 100644
--- a/README.md
+++ b/README.md
@@ -2,36 +2,78 @@
 
 Database document generator
 
-# Features
+you could use `databasir` to generate database meta model, or render it as markdown / pdf (TODO) / html (TODO)
 
-- render as markdown
-- render as html (TODO)
-- render as PDF (TODO)
+# How to use
 
-# Quick Start
+## Database Meta to Java Model
 
 ```java
-// First: get database connection
-Class.forName("com.mysql.cj.jdbc.Driver");
-Properties info=new Properties();
-info.put("user","root");
-info.put("password","123456");
-// this config is used by mysql
-info.put("useInformationSchema","true");
-String url="jdbc:mysql://localhost:3306/patient?useUnicode=true&characterEncoding=UTF-8&useSSL=false&allowPublicKeyRetrieval=true";
-var connection=DriverManager.getConnection(url,info);
-
-// Second: generate doc model
-var config=DatabaseDocConfiguration.builder()
-    .databaseName("patient")
-    .connection(connection)
-    .build();
+java.sql.Connection connection = ...;
+DatabaseDocConfig config = DatabaseDocConfig.builder()
+        .databaseName("Demo")
+        .connection(connection)
+        .build();
 DatabaseDoc doc = JdbcDatabaseDocFactory.of().create(config).orElseThrow();
+```
 
-// Final: Render as markdown
-try(FileOutputStream out=new FileOutputStream("doc.md")){
-    MarkdownRender.of(new RenderConfiguration()).rendering(doc,out);
-}catch(IOException e){
+## Render as Markdown
+```java
+java.sql.Connection connection = ...;
+DatabaseDocConfig config = DatabaseDocConfig.builder()
+        .databaseName("Demo")
+        .connection(connection)
+        .build();
+DatabaseDoc doc = JdbcDatabaseDocFactory.of().create(config).orElseThrow();
+try (FileOutputStream out = new FileOutputStream("doc.md")) {
+    RenderConfig renderConfig = new RenderConfig();
+    Render.markdownRender(renderConfig).rendering(doc, out);
+} catch (IOException e) {
     throw new IllegalStateException(e);
 }
-```
\ No newline at end of file
+```
+
+- Example
+
+![](README/table-doc.png)
+
+
+## Ignore tables or columns
+
+support regex pattern to ignore table or column
+
+```java
+java.sql.Connection connection = ...;
+DatabaseDocConfig config = DatabaseDocConfig.builder()
+        .databaseName("Demo")
+        .connection(connection)
+        .ignoreTableRegexes(Arrays.asList("mysql_*"))
+        .ignoreColumnRegexes(Arrays.asList("id"))
+        .build();
+DatabaseDoc doc = JdbcDatabaseDocFactory.of().create(config).orElseThrow();
+```
+
+## Extension
+
+Default factory
+
+- tableDocFactory ->  `com.databasir.core.doc.factory.jdbc.JdbcTableDocFactory`
+- columnDocFactory -> `com.databasir.core.doc.factory.jdbc.JdbcTableColumnDocFactory`
+- indexDocFactory -> `com.databasir.core.doc.factory.jdbc.JdbcTableIndexDocFactory`
+- triggerDocFactory -> `com.databasir.core.doc.factory.jdbc.JdbcTableTriggerDocFactory`
+
+Custom configuration
+```java
+java.sql.Connection connection = ...;
+DatabaseDocConfig config = DatabaseDocConfig.builder()
+        .databaseName("Demo")
+        .connection(connection)
+        .tableDocFactory(...) // your custom table doc factory
+        .tableColumnDocFactory(...) // your custom column doc factory
+        .tableIndexDocFactory(...) // your custom index doc factory
+        .tableTriggerDocFactory(...) // your custom trigger doc factory
+        .build();
+DatabaseDoc doc = JdbcDatabaseDocFactory.of().create(config).orElseThrow();
+```
+
+
diff --git a/README/table-doc.png b/README/table-doc.png
new file mode 100644
index 0000000..4631cbf
Binary files /dev/null and b/README/table-doc.png differ
diff --git a/core/src/main/java/com/databasir/core/doc/factory/DatabaseDocConfig.java b/core/src/main/java/com/databasir/core/doc/factory/DatabaseDocConfig.java
index 63559d0..3afb89f 100644
--- a/core/src/main/java/com/databasir/core/doc/factory/DatabaseDocConfig.java
+++ b/core/src/main/java/com/databasir/core/doc/factory/DatabaseDocConfig.java
@@ -26,9 +26,6 @@ public class DatabaseDocConfig {
     @Builder.Default
     private List<String> ignoreColumnRegexes = Collections.emptyList();
 
-    @Builder.Default
-    private DatabaseDocFactory databaseDocFactory = new JdbcDatabaseDocFactory();
-
     @Builder.Default
     private TableDocFactory tableDocFactory = new JdbcTableDocFactory();
 
diff --git a/core/src/test/java/App.java b/core/src/test/java/App.java
index f40f188..7d6b01d 100644
--- a/core/src/test/java/App.java
+++ b/core/src/test/java/App.java
@@ -25,14 +25,14 @@ public class App {
 
         // generate doc model
         var config = DatabaseDocConfig.builder()
-                .databaseName("patient")
+                .databaseName("user")
                 .connection(connection)
                 .tableTriggerDocFactory(new MysqlTableTriggerDocFactory())
                 .build();
         DatabaseDoc doc = JdbcDatabaseDocFactory.of().create(config).orElseThrow();
 
         // render as markdown
-        try (FileOutputStream out = new FileOutputStream("doc.md")) {
+        try (FileOutputStream out = new FileOutputStream("user.md")) {
             RenderConfig renderConfig = new RenderConfig();
             renderConfig.setRenderTriggers(true);
             Render.markdownRender(renderConfig).rendering(doc, out);