MyBatis Cursor: Read Large Data Efficiently

1 year ago
Noah Thompson
1 minute

In MyBatis, you can use a cursor to fetch query results row by row. This allows avoiding loading all data into memory at once, making it useful for handling large amounts of data.

The method for reading data using cursors is as follows:

  1. Define a method in the Mapper interface that returns a Cursor type, for example:
Cursor<User> getUserCursor();
  1. Write the corresponding SQL statements in the Mapper XML file, and use cursors to fetch data, for example:
<select id="getUserCursor" resultType="User" statementType="CALLABLE">
    {call get_users_cursor(#{result, mode=OUT, jdbcType=CURSOR, javaType=ResultSet})}
</select>
  1. When calling the method of the Mapper interface, you can obtain a Cursor object to retrieve the query results row by row, for example:
try (Cursor<User> cursor = userMapper.getUserCursor()) {
    while (cursor.hasNext()) {
        User user = cursor.next();
        // 处理每一行数据
    }
}

By using the above method, you can use a cursor to read the query result set line by line, avoiding loading all data into memory at once, improving performance and reducing memory consumption.

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