1

我将尝试直接用代码描述我的问题，然后说我需要什么，请注意，我已将我的代码最小化，以解决我遇到的问题：

我从 Entity 获取提要列表：

@Entity
public class Feed {

    @Id
    @Column
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @ManyToOne
    @JoinColumn(name = "event_id")
    private Event event;

    @ManyToOne
    @JoinColumn(name = "event_trigger_id")
    private EventTypeTrigger eventTrigger;
}

在这里，我试图让这个实体充满正确的count值。

@Entity
public class EventTrigger {

    @Id
    @Column
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(nullable = false)
    private String title;

    @Transient
    private int count;
}

存储计数数据的提要实体。

@Entity
public class EventTriggerFeed {
    @Id
    @Column
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;


    @Column(nullable = false)
    private int count;

    @ManyToOne
    @JoinColumn(name = "event_id", nullable = false)
    @JsonBackReference
    private Event event;

    @ManyToOne
    @JoinColumn(name = "event_trigger_id", nullable = false)
    @JsonBackReference
    private EventTrigger eventTrigger;
}

从我尝试调用的服务中：

public List<Feed> findUserFeeds(int userId) {
        return Ebean.find(Feed.class).findList();
    }

我可以像这样获得每个触发器的计数：

public int getCountFromEventTriggerFeed(int triggerId, int eventId) {
        return Ebean.find(EventTriggerFeed.class)
                .where().eq("eventTrigger.id",triggerId).eq("event.id",eventId)
                .findUnique().getCount();
    }

我只是想获取Feed具有Event信息和EventTrigger信息的列表，并且count属性填充了来自的计数值EventTriggerFeed

我只是在没有太多迭代的情况下坚持了完美的方式，我正在考虑获取每个EventTrigger内行的计数值Feed，但这可能会导致我打很多电话：

for (Feed feed : findUserFeeds(userId)) {
    int eventId = feed.getEvent().getId();
    int triggerId = feed.getEventTrigger().getId();
    feed.getEventTrigger().setCount(getCountFromEventTriggerFeed(triggerId, eventId))
}

但是你能想象如果我有 50 个提要吗？

有没有关于如何优化这个头痛的想法？

4

1 回答 1

0

我通过在文件中创建视图来解决这个问题，.sql如下所示：

CREATE OR REPLACE VIEW `event_feed_summary_view` AS
  SELECT
    max(feed.trigger_count) * up.amount AS total_amount,
    feed.trigger_count,
    uf.feed_id,
    feed.event_id,
    feed.event_trigger_id,
    up.amount
  FROM event_trigger_feeds feed
    INNER JOIN event_type_triggers trig ON feed.event_trigger_id AND trig.id
    INNER JOIN user_feed uf ON uf.event_id = feed.event_id AND uf.event_trigger_id = feed.event_trigger_id
  GROUP BY uf.feed_id, feed.event_id, feed.event_trigger_id;

我把这段代码放在里面conf/db_views/create_views.sql

我在我的模块中启动时调用了这个文件OnStartup：

@Singleton
public class OnStartup {

    @Inject
    public OnStartup(final Configuration configuration, final Environment environment, Database db) {


        // Create views
            Logger.info("Creating / Replacing the Tables views in database");
            InputStream is = environment.classLoader().getResourceAsStream("db_views/create_views.sql");
            String sql;
            try {
                sql = IOUtils.toString(is);
                if (sql != null) {
                    Connection conn = db.getConnection();
                    try {
                        Statement stmt = conn.createStatement();
                        try {
                            stmt.execute(sql);
                            Logger.info("Views Created");
                        } finally {
                            try {
                                stmt.close();
                            } catch (SQLException e) {
                                e.printStackTrace();
                            }
                        }
                    } catch (SQLException e) {
                        Logger.error("Could create Statement ");
                        e.printStackTrace();
                    } finally {
                        try {
                            conn.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
                }
            } catch (IOException e) {
                Logger.error("Could not find create view script");
                e.printStackTrace();
            }
    }
}

使用 Ebean 我得到的结果是SqlQuery：

public long getTotal(int feedId) {
    String sql = "select sum(total_amount) as total from event_feed_summary_view where feed_id = :feed_id;";
    SqlQuery sqlQuery = Ebean.createSqlQuery(sql);
    sqlQuery.setParameter("feed_id", feedId);
    SqlRow r = sqlQuery.findUnique();
    if (r != null && r.getLong("total") != null) {
        return r.getLong("total");
    }
    return 0;
}
于 2016-04-19T14:46:11.917 回答