Question

我对Postgres很新，需要获取两个独立的数据： 1）表T1的各种记录/结果的avg，min，max的值 2）基于最新时间戳

的表T1的“最后”记录的列值

问题是我无法单独运行这些查询，因为它会导致性能问题。（此表中的数据可以是数万个或记录，并将它们组合成结果对象，甚至更复杂）。

是否可以将这两个数据的结果并排组合成一个将返回所需输出的查询怪物？

感谢您的帮助。

更新了查询：

第一次查询：

select
    rtp.id, rtp.received_timestamp,
    rtp.agent_time, rtp.sourceip, rtp.destip, rtp.sourcedscp,
    sum(rtp.numduplicate) as dups, avg(rtp.numduplicate) as avgdups,
    min(rtp.numduplicate) as mindups, max(rtp.numduplicate) as maxdups
from rtp_test_result rtp
where
    rtp.received_timestamp between 1274723208 and 1475642299
group by rtp.sourceip, rtp.destip, rtp.sourcedscp
order by rtp.sourceip, rtp.destip, rtp.sourcedscp

第二次查询：

select id, received_timestamp, numooo
from rtp_test_result 
where received_timestamp = (select max(received_timestamp) mrt from rtp_test_result)
group by id,received_timestamp, numooo 
order by id desc limit 1

Answer 1

类似

with cte as (
    select
        val,
        last_value(val) over(order by ts asc rows between unbounded preceding and unbounded following) as lst_value
    from T1
)
select
    avg(val) as avg_value,
    min(val) as min_value,
    max(val) as max_value,
    max(lst_value) as lst_value
from cte

或

select
    avg(val) as avg_value,
    min(val) as min_value,
    max(val) as max_value,
    (select val from T1 order by ts desc limit 1) as lst_value
from T1

sql fiddle demo

合并两个独立查询的结果

1 个答案: