MyBatis Cursor Guide for Large Data

1 year ago
Ava Mitchell
1 minute

In MyBatis, you can use a Cursor to handle large data queries in order to reduce memory consumption. Cursors allow you to retrieve query results one by one, instead of loading all results into memory at once. In MyBatis, you can specify the use of a Cursor for data retrieval by setting the fetchType attribute in the select tag, for example:

<select id="selectUsers" resultType="User" fetchType="lazyLoading">
    SELECT * FROM users 
</select>

In this example, data is queried using the Cursor method by specifying fetchType=”lazyLoading”. When calling this query method, MyBatis will return a Cursor object, allowing data to be retrieved one by one from the Cursor object.

Alternatively, you can also utilize the org.apache.ibatis.cursor.Cursor interface to handle Cursor objects, for example:

try (SqlSession session = sqlSessionFactory.openSession()) {
    try (Cursor<User> cursor = session.selectCursor("selectUsers")) {
        for (User user : cursor) {
            // 处理查询结果
        }
    }
}

In this example, a Cursor object is obtained using the session.selectCursor method, and the query results can be processed one by one through a for loop. It is important to remember to manually close the Cursor object after processing all the data to release resources.

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