Update all JSON type mappings to VARIANT

Change JSON type mappings to VARIANT across all migration docs:
- PostgreSQL: json/jsonb → VARIANT
- MySQL: JSON → VARIANT
- Elasticsearch: object, flattened → VARIANT

VARIANT type provides better flexible schema support for semi-structured
data migration. Added links to VARIANT documentation.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dataroaring

docs/migration/elasticsearch-to-doris.md

@@ -49,8 +49,8 @@ This guide covers migrating data from Elasticsearch to Apache Doris. Doris can s
 | date | DATE or DATETIME | See [Date Handling](#handling-date-types) |
 | ip | STRING | |
 | nested | VARIANT | See [VARIANT type](../data-operate/import/complex-types/variant.md) for flexible schema |
-| object | JSON | |
-| flattened | JSON | Supported since Doris 3.1.4, 4.0.3 |
+| object | VARIANT | See [VARIANT type](../data-operate/import/complex-types/variant.md) |
+| flattened | VARIANT | Supported since Doris 3.1.4, 4.0.3 |
 | geo_point | STRING | Store as "lat,lon" string |
 | geo_shape | STRING | Store as GeoJSON string |
 

docs/migration/mysql-to-doris.md

@@ -39,7 +39,7 @@ This guide covers migrating data from MySQL to Apache Doris. MySQL is one of the
 | TEXT / MEDIUMTEXT / LONGTEXT | STRING | |
 | BINARY / VARBINARY | STRING | |
 | BLOB / MEDIUMBLOB / LONGBLOB | STRING | |
-| JSON | JSON | |
+| JSON | VARIANT | See [VARIANT type](../data-operate/import/complex-types/variant.md) |
 | ENUM | STRING | |
 | SET | STRING | |
 | BIT | BOOLEAN / BIGINT | BIT(1) maps to BOOLEAN |

docs/migration/postgresql-to-doris.md

@@ -37,7 +37,7 @@ This guide covers migrating data from PostgreSQL to Apache Doris. You can choose
 | date | DATE | |
 | time | STRING | Doris does not support TIME type |
 | interval | STRING | |
-| json / jsonb | JSON or STRING | Use STRING for better query performance |
+| json / jsonb | VARIANT | See [VARIANT type](../data-operate/import/complex-types/variant.md) for flexible schema |
 | uuid | STRING | |
 | bytea | STRING | |
 | array | ARRAY | See [Handling Arrays](#handling-arrays) |
@@ -379,7 +379,7 @@ FROM pg_catalog.schema.pg_table;
 
 ### Handling JSON/JSONB
 
-For complex JSON queries, map to Doris STRING and use JSON functions:
+PostgreSQL JSON/JSONB maps to Doris VARIANT type, which supports flexible schema and efficient JSON operations:
 
 ```sql
 -- Query JSON fields

i18n/zh-CN/docusaurus-plugin-content-docs/current/migration/elasticsearch-to-doris.md

@@ -49,8 +49,8 @@
 | date | DATE 或 DATETIME | 参见[日期处理](#处理日期类型) |
 | ip | STRING | |
 | nested | VARIANT | 参见 [VARIANT 类型](../data-operate/import/complex-types/variant.md)，支持灵活 Schema |
-| object | JSON | |
-| flattened | JSON | Doris 3.1.4、4.0.3 起支持 |
+| object | VARIANT | 参见 [VARIANT 类型](../data-operate/import/complex-types/variant.md) |
+| flattened | VARIANT | Doris 3.1.4、4.0.3 起支持 |
 | geo_point | STRING | 存储为 "lat,lon" 字符串 |
 | geo_shape | STRING | 存储为 GeoJSON 字符串 |
 

i18n/zh-CN/docusaurus-plugin-content-docs/current/migration/mysql-to-doris.md

@@ -39,7 +39,7 @@
 | TEXT / MEDIUMTEXT / LONGTEXT | STRING | |
 | BINARY / VARBINARY | STRING | |
 | BLOB / MEDIUMBLOB / LONGBLOB | STRING | |
-| JSON | JSON | |
+| JSON | VARIANT | 参见 [VARIANT 类型](../data-operate/import/complex-types/variant.md) |
 | ENUM | STRING | |
 | SET | STRING | |
 | BIT | BOOLEAN / BIGINT | BIT(1) 映射为 BOOLEAN |

i18n/zh-CN/docusaurus-plugin-content-docs/current/migration/postgresql-to-doris.md

@@ -37,7 +37,7 @@
 | date | DATE | |
 | time | STRING | Doris 不支持 TIME 类型 |
 | interval | STRING | |
-| json / jsonb | JSON 或 STRING | 使用 STRING 可获得更好的查询性能 |
+| json / jsonb | VARIANT | 参见 [VARIANT 类型](../data-operate/import/complex-types/variant.md)，支持灵活 Schema |
 | uuid | STRING | |
 | bytea | STRING | |
 | array | ARRAY | 参见[处理数组](#处理数组) |
@@ -367,7 +367,7 @@ FROM pg_catalog.schema.pg_table;
 
 ### 处理 JSON/JSONB
 
-对于复杂的 JSON 查询，映射到 Doris STRING 并使用 JSON 函数：
+PostgreSQL JSON/JSONB 映射到 Doris VARIANT 类型，支持灵活 Schema 和高效的 JSON 操作：
 
 ```sql
 -- 查询 JSON 字段