Question

我使用GridGain作为我的数据对象（pojos）的本地内存存储，我需要查询这些对象并选择具有特定值的正确对象。让我们考虑以下情况：

class Person {

    public Long id;
    public String name;
    public Organization organization;
}

class Organization{

  public Long id;
  public String name;
}

您能否建议如何进行查询以便检索，例如特定组织的所有人？我试过以下：

final GridCacheProjection<GridCacheAffinityKey<Long>, Person> appCache = cache.projection(GridCacheAffinityKey.class, Person.class);

final GridCacheQuery<Map.Entry<GridCacheAffinityKey<Long>, Person>> query = appCache.queries().createSqlQuery(Person.class, "from Person, Organization " + "where Person.organization.id = " + "Organization.id = ?");

但没有运气。我发现很多使用Person.id = Organization.id =的例子？但是我将Organization作为Person类中的对象，那么如何以这种方式编写查询或检索数据？

提前感谢任何提示。

Answer 1

您的代码看起来不正确。

查看GitHub上提供的CacheQueryExample（也随GridGain一起提供）

特别是在进行连接的部分：

// Create query which joins on 2 types to select people for a specific organization.
GridCacheQuery<Map.Entry<GridCacheAffinityKey<UUID>, Person>> qry = cache.queries().
    createSqlQuery(Person.class,
        "from Person, Organization " + "where Person.orgId = Organization.id and " +
        "lower(Organization.name) = lower(?)");

// Execute queries for find employees for different organizations.
print("Following people are 'GridGain' employees: ", qry.execute("GridGain").get());
print("Following people are 'Other' employees: ", qry.execute("Other").get());

GridGain连接两个对象的查询

1 个答案: