cassandra - Apache Cassandra - 以 LIMIT 作为参数的访问器不起作用

Question

我正在尝试将参数传递给访问器查询。我有以下内容:

@Accessor
public interface ActivityAccessor {

    @Query("SELECT * FROM activity WHERE user_id = :id limit :limit")
    Result<UserActivity> findUserActivityByUserId(@Param("id") Long ownerId, @Param("limit") int limit);
}

调用访问器方法:

MappingManager manager = new MappingManager (getSession());
ActivityAccessor activityAccessor = manager.createAccessor(ActivityAccessor.class);
Result<UserActivity> activities = activityAccessor.findUserActivityByUserId(userId, 20);

我收到以下错误:

Caused by: com.datastax.driver.core.exceptions.SyntaxError: line 1:99 no viable alternative at input 'limit' (... LIMIT :[limit])

但是，当我更改访问器方法以明确声明限制值时，它工作得很好:

@Query("SELECT * FROM activity WHERE user_id = :id limit 20")
Result<UserActivity> findUserActivityByUserId(@Param("id") Long ownerId);

有人知道为什么会发生这种情况吗？

Answer 1

limit 是保留的 CQL 关键字，不能用作命名参数。把它换成别的东西。例如:

@Query("SELECT * FROM activity WHERE user_id = :id limit :max")
Result<UserActivity> findUserActivityByUserId(@Param("id") Long ownerId, @Param("max") int limit);