[apache#2323] docs: document UnparsedType data type which handles a…

…n unresolvable type from the catalog (apache#2337)

### What changes were proposed in this pull request?

Document `UnparsedType` data type which handles an unresolvable type
from the catalog.

### Why are the changes needed?

`UnparsedType` data type that handles an unresolvable type from the
catalog is supported in apache#2140.

Fix: apache#2323

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

No.

docs/apache-hive-catalog.md

@@ -116,6 +116,10 @@ The following table lists the data types mapped from the Hive catalog to Graviti
 | `struct`                    | `struct`            | 0.2.0         |
 | `uniontype`                 | `uniontype`         | 0.2.0         |
 
+:::info
+Since 0.5.0, the data types other than listed above are mapped to Gravitino **[Unparsed Type](./manage-metadata-using-gravitino.md#unparsed-type)** that represents an unresolvable data type from the Hive catalog.
+:::
+
 ### Table properties
 
 Table properties supply or set metadata for the underlying Hive tables.

docs/jdbc-mysql-catalog.md

@@ -103,6 +103,7 @@ Please refer to [Manage Metadata Using Gravitino](./manage-metadata-using-gravit
 
 :::info
 MySQL doesn't support Gravitino `Boolean` `Fixed` `Struct` `List` `Map` `Timestamp_tz` `IntervalDay` `IntervalYear` `Union` `UUID` type.
+Meanwhile, the data types other than listed above are mapped to Gravitino **[Unparsed Type](./manage-metadata-using-gravitino.md#unparsed-type)** that represents an unresolvable data type since 0.5.0.
 :::
 
 #### Table column auto-increment

docs/jdbc-postgresql-catalog.md

@@ -108,6 +108,7 @@ Please refer to [Manage Metadata Using Gravitino](./manage-metadata-using-gravit
 
 :::info
 PostgreSQL doesn't support Gravitino `Fixed` `Struct` `List` `Map` `IntervalDay` `IntervalYear` `Union` `UUID` type.
+Meanwhile, the data types other than listed above are mapped to Gravitino **[Unparsed Type](./manage-metadata-using-gravitino.md#unparsed-type)** that represents an unresolvable data type since 0.5.0.
 :::
 
 #### Table column auto-increment

docs/lakehouse-iceberg-catalog.md

@@ -215,6 +215,7 @@ Apache Iceberg doesn't support Gravitino `EvenDistribution` type.
 
 :::info
 Apache Iceberg doesn't support Gravitino `Varchar` `Fixedchar` `Byte` `Short` `Union` type.
+Meanwhile, the data types other than listed above are mapped to Gravitino **[Unparsed Type](./manage-metadata-using-gravitino.md#unparsed-type)** that represents an unresolvable data type since 0.5.0.
 :::
 
 ### Table properties

docs/manage-metadata-using-gravitino.md

@@ -609,8 +609,8 @@ You can create a table by sending a `POST` request to the `/api/metalakes/{metal
 ```shell
 curl -X POST -H "Accept: application/vnd.gravitino.v1+json" \
 -H "Content-Type: application/json" -d '{
-  "name": "exmaple_table",
-  "comment": "This is an exmaple table",
+  "name": "example_table",
+  "comment": "This is an example table",
   "columns": [
     {
       "name": "id",
@@ -756,7 +756,7 @@ Map<String, String> tablePropertiesMap = ImmutableMap.<String, String>builder()
         .build();
 
 tableCatalog.createTable(
-  NameIdentifier.of("metalake", "catalog", "schema", "exmaple_table"),
+  NameIdentifier.of("metalake", "catalog", "schema", "example_table"),
   new Column[] {
     Column.of("id", Types.IntegerType.get(), "id column comment", false, true, Literals.integerLiteral(-1)),
     Column.of("name", Types.VarCharType.of(500), "name column comment", true, false, Literals.NULL),
@@ -768,7 +768,7 @@ tableCatalog.createTable(
       ), "info column comment", true, false, null),
     Column.of("dt", Types.DateType.get(), "dt column comment", true, false, null)
   },
-  "This is an exmaple table",
+  "This is an example table",
   tablePropertiesMap,
   new Transform[] {Transforms.identity("id")},
   Distributions.of(Strategy.HASH, 32, NamedReference.field("id")),
@@ -823,6 +823,32 @@ The following types that Gravitino supports:
 
 The related java doc is [here](pathname:///docs/0.4.0/api/java/com/datastrato/gravitino/rel/types/Type.html).
 
+##### Unparsed type
+
+Unparsed type is a special type of column type, currently serves exclusively for presenting the data type of a column when it's unsolvable.
+The following shows the data structure of an unparsed type in JSON and Java, enabling easy retrieval of its value.
+
+<Tabs>
+  <TabItem value="Json" label="Json">
+
+```json
+{
+  "type": "unparsed",
+  "unparsedType": "user-defined"
+}
+```
+
+  </TabItem>
+  <TabItem value="java" label="Java">
+
+```java
+// The result of the following type is a string "user-defined"
+String unparsedValue = ((UnparsedType) type).unparsedType();
+```
+
+  </TabItem>
+</Tabs>
+
 #### Table column default value
 
 When defining a table column, you can specify a [literal](./expression.md#literal) or an [expression](./expression.md) as the default value. The default value typically applies to new rows that are inserted into the table by the underlying catalog.
@@ -906,7 +932,8 @@ tableCatalog.loadTable(NameIdentifier.of("metalake", "hive_catalog", "schema", "
 </Tabs>
 
 :::note
-When Gravitino loads a table from a catalog that supports default value, if Gravitino is unable to parse the default value, it will use an **[Unparsed Expression](./expression.md#unparsed-expression)** to preserve the original default value, ensuring that the table can be loaded successfully.
+- When Gravitino loads a table from a catalog with various data types, if Gravitino is unable to parse the data type, it will use an **[Unparsed Type](#unparsed-type)** to preserve the original data type, ensuring that the table can be loaded successfully.
+- When Gravitino loads a table from a catalog that supports default value, if Gravitino is unable to parse the default value, it will use an **[Unparsed Expression](./expression.md#unparsed-expression)** to preserve the original default value, ensuring that the table can be loaded successfully.
 :::
 
 ### Alter a table

docs/open-api/datatype.yaml

@@ -14,6 +14,7 @@ components:
         - $ref: "#/components/schemas/ListType"
         - $ref: "#/components/schemas/MapType"
         - $ref: "#/components/schemas/UnionType"
+        - $ref: "#/components/schemas/UnparsedType"
 
     PrimitiveType:
       type: string
@@ -162,4 +163,24 @@ components:
         comment:
           type: string
           description: The comment of the struct field
-          nullable: true
+          nullable: true
+
+    UnparsedType:
+      type: object
+      required:
+        - type
+        - unparsedType
+      properties:
+        type:
+          type: string
+          enum:
+            - "unparsed"
+        unparsedType:
+          type: string
+          description: The unparsed type
+      example: {
+        "type": "unparsed",
+        "unparsedType": [
+          "user-defined"
+        ]
+      }