更高效的 SQLite 触发器“汇总”多行

Question

我正在从我的路由器收集传输数据；它提供每日、每月和每两分钟（间隔 120 秒）的摘要。如果我在一天中（因此在月中）重新启动路由器，这些报告将不完整。但是，我仍然有区间数据，并且可以汇总启动前后的记录。

以前，我在更新三个单独的表后使用脚本执行了此汇总操作。这很慢，因为我必须查询给定日期间隔的总和，然后是月份间隔。更新间隔时执行汇总会更快。所以我把一个触发器放在一起。问题是我编写触发器的方式，它更新每个间隔插入的每日和每月行。理想情况下，每个事务只发生一次，并处理刚刚添加的行。

所以，下面是一个包含的示例，显示了我所拥有的。计数列只是为了说明汇总发生的次数超出了它的需要。有没有办法简化这一点？

BEGIN TRANSACTION;

CREATE TABLE monthly  (count INTEGER DEFAULT 0, date DATE NOT NULL, interface TEXT NOT NULL, upload INTEGER DEFAULT 0, download INTEGER DEFAULT 0, rollup_upload INTEGER DEFAULT 0, rollup_download INTEGER DEFAULT 0, PRIMARY KEY (date, interface));
CREATE TABLE daily    (count INTEGER DEFAULT 0, date DATE NOT NULL, interface TEXT NOT NULL, upload INTEGER DEFAULT 0, download INTEGER DEFAULT 0, rollup_upload INTEGER DEFAULT 0, rollup_download INTEGER DEFAULT 0, PRIMARY KEY (date, interface));
CREATE TABLE interval (count INTEGER DEFAULT 0, date DATE NOT NULL, interface TEXT NOT NULL, upload INTEGER DEFAULT 0, download INTEGER DEFAULT 0, interval INTEGER, PRIMARY KEY (date, interface));

CREATE TRIGGER rollup_interval_trigger AFTER INSERT ON interval
BEGIN

INSERT OR REPLACE INTO daily (count, date, interface, upload, download, rollup_upload, rollup_download)
SELECT
    COALESCE((SELECT count FROM daily WHERE date IS strftime('%Y-%m-%d', NEW.date, 'localtime') AND interface IS 'wan'),0)+1,
    strftime('%Y-%m-%d', NEW.date, 'localtime'),
    'wan',
    COALESCE((SELECT upload FROM daily WHERE date IS strftime('%Y-%m-%d', NEW.date, 'localtime') AND interface IS 'wan'),0),
    COALESCE((SELECT download FROM daily WHERE date IS strftime('%Y-%m-%d', NEW.date, 'localtime') AND interface IS 'wan'),0),
    sum(upload) as rollup_upload,
    sum(download) as rollup_download
FROM interval
WHERE strftime('%Y-%m-%d', date, 'localtime') = strftime('%Y-%m-%d', NEW.date, 'localtime') AND interface IS 'vlan2';

INSERT OR REPLACE INTO monthly (count, date, interface, upload, download, rollup_upload, rollup_download)
SELECT
    COALESCE((SELECT count FROM monthly WHERE date IS strftime('%Y-%m-01', NEW.date, 'localtime') AND interface IS 'wan'),0)+1,
    strftime('%Y-%m-01', NEW.date, 'localtime'),
    'wan',
    COALESCE((SELECT upload FROM monthly WHERE date IS strftime('%Y-%m-01', NEW.date, 'localtime') AND interface IS 'wan'),0),
    COALESCE((SELECT download FROM monthly WHERE date IS strftime('%Y-%m-01', NEW.date, 'localtime') AND interface IS 'wan'),0),
    sum(upload) as rollup_upload,
    sum(download) as rollup_download
FROM interval
WHERE strftime('%Y-%m', date, 'localtime') = strftime('%Y-%m', NEW.date, 'localtime') AND interface IS 'vlan2';

END;

COMMIT;

insert into daily (date, interface, download, upload) values ('2012-10-02', 'wan', 10, 20);
insert into monthly (date, interface, download, upload) values ('2012-10-01', 'wan', 30, 40);

.headers ON

select * from daily;
select * from monthly;

begin transaction;
insert into interval (date, interval, download, upload, interface) values ('2012-10-02 11:00:00', 120, 10, 20, 'vlan2');
insert into interval (date, interval, download, upload, interface) values ('2012-10-02 12:00:00', 120, 10, 20, 'vlan2');
insert into interval (date, interval, download, upload, interface) values ('2012-10-02 13:00:00', 120, 10, 20, 'vlan2');
insert into interval (date, interval, download, upload, interface) values ('2012-10-02 14:00:00', 120, 10, 20, 'vlan2');
insert into interval (date, interval, download, upload, interface) values ('2012-10-01 12:00:00', 120, 10, 20, 'vlan2');
insert into interval (date, interval, download, upload, interface) values ('2012-10-03 12:00:00', 120, 10, 20, 'vlan2');
commit;

select * from interval;

select * from daily;
select * from monthly;

Answer 1

仅通过插入间隔的新数字来增加每日和每月的计数怎么样？然后你不会在每个插入上聚合。您所拥有的只是按主键两次查找一行并更新该行。

CREATE TRIGGER rollup_interval_trigger AFTER INSERT ON interval
BEGIN
    INSERT INTO daily 
    SELECT 0, strftime('%Y-%m-%d', NEW.date, 'localtime'), 'wan',0,0,0,0 
    WHERE NOT EXISTS (
      SELECT 1 
      FROM daily 
      WHERE date = strftime('%Y-%m-%d', NEW.date, 'localtime') and interface = 'wan');

    UPDATE daily 
    SET count = count + 1,
        rollup_upload = rollup_upload + new.upload ,
        rollup_download = rollup_download + new.download 
    WHERE date = strftime('%Y-%m-%d', NEW.date, 'localtime') and interface = 'wan';

    -- and similarly for table monthly
END;

由于 sqlite 没有“upsert”语句，因此您需要有一个单独的语句来创建每日/每月记录，如果它们在更新之前还没有。

这给出了与您的测试数据触发器相同的结果。

附言

如果需要，您还可以通过 INSERT 或 IGNORE 替换 INSERT ... WHERE NOT EXISTS 以获得最佳性能（我不太喜欢它，因为它捕获 所有 冲突，而不仅仅是唯一的约束，并且通常可能隐藏其他错误）。